
LIBRARY OF CONGRESS. 



§Jmp..-.-— @np|rigW If o, - 

Shelf ..^A-fc* 

CNITED STATES OF AMERICA. 




CHEMISTRY: 



General, Medical, and Pharmaceutical, 



THE CHEMISTRY OF THE U. S. PHARMACOPEIA. 



A MANUAL 

ON THE GENERAL PRINCIPLES OF THE SCIENCE, AND THEIR 
APPLICATIONS IN MEDICINE AND PHARMACY. 



BY 

JOHN ATTFIELD, F.R.S., 

Ph.D. of the University of Tubingen, F. I. C. ; F. C. S; 

Professor of Practical Chemistry to the Pharmaceutical Society of Great Britain ; 

Formerly Demonstrator of Chemistry at St. Bartholomew's Hospital, London ; 

Honorary Member of the Pharmaceutical Societies of Great Britain, St. Petersburg, Austria, 

Denmark, East Flanders, Switzerland, Australasia, New South Wales, and Queensland ; 

Honorary Member of the American Pharmaceutical Association ; 

Honorary Corresponding Member of the Society of Pharmacy of Paris; 

Honorary Member of the Colleges of Pharmacy of Philadelphia, New York, 

Massachusetts, Chicago, and Ontario, and of the Pharmaceutical Associations of New 

Hampshire, Virginia, Liverpool, Manchester, Georgia, Maryland, and 

the Province of Quebec ; 

Editor of the British Pharmacopoeia; 

Annual Reporter of the British Pharmacopoeia to the Medical Council; 

Author of a Handbook on Water and Water-Supplies. 



FOURTEENTH EDITION. 




Si 



*7 



&fy 



PHILADELPHIA : 

LEA BROTHERS & CO. 

1894. 



Entered according to Act of Congress, in the year 1894, by 

LEA BROTHERS & CO., 

in the Office of the Librarian of Congress, at Washington. All rights reserved. 



"But the greatest error of all is, mistaking the ultimate end of knowledge; for 
some men covet knowledge out of a natural curiosity and inquisitive temper; some 
to entertain the mind with variety and delight ; some for ornament and reputation ; 
some for victory and contention ; many for lucre and a livelihood ; and but few 
for employing the divine gift of reason to the use and benefit of mankind." — Lord 
Bacon. 

"I hold tbat the greatest friend to man is labor; that knowledge without toil, 
if possible, were worthless; that toil in pursuit of knowledge is the best know- 
ledge we can attain ; that the continuous effort for fame is nobler than fame itself; 
that it is not wealth suddenly acquired which is deserving of homage, but the 
virtues which a man exercises in the slow pursuit of wealth— the abilities so called 
forth, the self-denials so imposed ; in a word, that Labor and Patience are the true 
schoolmasters on earth." — Lord Lytton. 

" I want to learn all that one human being can. It is awful to be buried alive in 
the coffin of one's own ignorance and helplessness."— Graham Travers. 



0- 



WESTCOTT & THOMSON, WiLLIAM J. DORNAN, 

ELECTROTYPERS, PHILADA. PRINTER, PHILADA. 



PREFACE. 



The short title on the back of a book, and even the words on 
the title-page, are generally, and even necessarily, imperfect 
descriptions of the contents, and hence not unfrequently induce 
at the outset misconceptions in the minds of readers. The 
author of Chemistry : General, Medical, and Pharmaceutical, 
would at once state, therefore, that his chief aim is to teach 
the general truths of chemistry to medical and pharmaceutical 
pupils. So far as laws and principles are concerned, the book 
is a work on General Chemistry ; but inasmuch as those laws 
and principles are elucidated and illustrated by that large por- 
tion of chemistry which is directly interesting to medical prac- 
titioners and pharmacists, the book may be said to be a work 
on Medical Chemistry and on Pharmaceutical Chemistry. Only 
in this conventional sense would the author speak of Medical 
and Pharmaceutical Chemistry ; for the truths of chemistry 
are the same for all students — crystalline verities which cannot 
be expanded or compressed to suit any class of workers. The 
leading principles of the science, however, can as easily be 
illustrated by or deduced from those facts which have interest 
as from those which have little or no special interest to the 
followers of medicine and pharmacy. The grand and simple 
leading truths or laws of chemistry, the lesser truths or prin- 
ciples, and nearly all the interesting relationships of elements 
and compounds — in a word, the science of chemistry — can be 
taught to medical and pharmaceutical students with little 
other aid than that afforded by the materials which lie in 
rich abundance all around these workers. Such a mode of 
teaching what is stated on the title-page as " the general prin- 
ciples of the science and their applications in medicine and 
pharmacy " is adopted in this volume. It is a mode which 
greatly increases the usefulness of the science to the students 



VI PREFACE. 

chiefly addressed, while it in no way diminishes the value of 
chemistry to them as an instrument of mental culture — an 
instrument which sharpens and expands the powers of observ- 
ation, which enlarges and strengthens memory and imagina- 
tion, which gives point to the perceptive faculties, and which 
develops and elaborates the powers of thought and of reason. 

This Manual is intended, then, as a systematic exponent of 
the general truths of chemistry, but is written mainly for the 
pupils, assistants, and principals engaged in medicine and phar- 
macy. It is essentially a Manual of Applied Chemistry or 
Technical Chemistry, but is first of all a Manual of Chemistry. 

The book will be found equally useful as a reading-book for 
students having no opportunities of attending lectures or per- 
forming experiments, or, on the other hand, as a text-book for 
college pupils ; while its comprehensive Index, containing 
nearly ten thousand references, will fit the work for after- 
consultation in the course of business or professional practice. 

From other chemical text-books it differs in three particu- 
lars : first, in the exclusion of matter relating to compounds 
which at present are only of interest to the scientific chemist ; 
secondly, in containing more or less of the chemistry of every 
substance recognized officially or in general practice as a 
remedial agent ; thirdly, in the paragraphs being so cast that 
the volume may be used as a guide in studying the science 
experimentally. 

The order of subjects is that which, in the author's opinion, 
best meets the requirements of medical and pharmaceutical 
students in Great Britain, Ireland, America, India, and the 
English colonies. Introductory pages are devoted to a few 
leading properties of the elements. A review of the facts 
thus unfolded affords opportunity for stating the views of 
philosophers respecting the manner in which these elements 
influence each other as components of terrestrial matter. The 
consideration in detail of the relations of the elementary and 
compound radicals follows, synthetical and analytical bearings 
being pointed out, and attention frequently directed to con- 
necting or underlying truths or general principles. The chem- 



PREFACE. Vll 

istry of substances met with in vegetables and animals, or of 
similar substances artificially produced (the so-called " organic 
chemistry "), is next considered. Chemical toxicology and the 
chemical as well as microscopical characters of morbid urine, 
urinary sediments, and calculi are then given. The concluding 
sections form a laboratory-guide to beginners in the chemical 
and physical study of quantitative analysis. In the Appendix 
is a long table of tests for impurities in medicinal preparations, 
a short one of the saturating-powers of acids and alkalies, 
designed for use in prescribing and dispensing, and an alpha- 
betical list of elements and atomic weights. 

In the course of the treatment outlined in the preceding 
paragraph it will be observed that the whole of the elements 
are first noticed very shortly, to give the pupil a general view 
of his course of study, and afterward at length and thor- 
oughly ; that the chemistry of the common metallic radicals 
precedes that of the rarer, and that the sections on the acid- 
ulous radicals are similarly divided ; while the basylous rad- 
icals are arranged according to analytical relations, the com- 
mon acidulous according to exchangeable value or quantiv- 
alence, and the rarer acidulous radicals alphabetically. By 
this plan the more important facts and principles are repeatedly 
brought under consideration, the points of view, however, dif- 
fering according as interest is concentrated on physical, syn- 
thetical, analytical, or quantitative properties. This arrange- 
ment of matter was adopted, also, partly in the belief that the 
separate and general truths of chemistry never do or can enter 
the mind in the order of any scientific classification at present 
possible. Chemical facts are not yet united by any single, 
consistent theory. Tn the current state of chemical knowledge 
consistency in the methodical arrangement even of elements 
can only be carried out in one direction, and is necessarily 
accompanied by inconsistencies in other directions — a result 
most perplexing to learners, and hence totally subversive of 
the chief advantages of classification. For this reason the 
writer has preferred to lead up to, rather than follow, scientific 
classification — has allowed analogies and affinities to suggest, 



VI 11 PREFACE. 

rather than be suggested by, classification. Among the acid- 
ulous radicals, especially, any known system of classification 
would have given undue prominence to one set of relations, 
and undeserved obscurity to others. Then, by separating 
more important from less important matter, instruction is 
adapted to the wants of gentlemen whose opportunities of 
studying chemistry vary greatly, and are unavoidably insuf- 
ficient to enable them to gain a knowledge of the whole area 
of the science. One great advantage of the mode of treat- 
ment is, that difficulties of nomenclature, notation, chemical 
constitution, and even those arising from conventionality of 
language, are explained as they arise, instead of being massed 
under the head of ." Introductory Chapters," " Preliminary 
Considerations," or " General Remarks," which are not unfre- 
quently too difficult to be understood by a beginner, too vo- 
luminous to be remembered except by the aid of subsequent 
lessons, and are consequently the cause of much trouble and 
confusion. For an illustration of the treatment thus adopted 
by the author the reader is referred to the various notes on 
chemical constitution. (See " Constitution," " Structure," etc. 
in the Index.) This plan has also admitted of greater prom- 
inence being given to " The General Principles of Chemical 
Philosophy," the only section to which the student is asked 
frequently to return until he finds himself naturally employing 
those principles in the interpretation of the phenomena obtained 
by experiment. 

An elementary knowledge of the subjects of Gravitation, 
Heat, Light, Sound, Electricity, and Magnetism cannot be too 
strongly recommended to the student of chemistry. The first 
portion of this Manual would have been devoted to an exposi- 
tion of these branches of physics, so far as they bear on chem- 
istry, did not the many special books on Physics render such a 
course unnecessary. Quantitative chemical analysis frequently 
involving determinations of temperature, specific gravity, and 
atmospheric pressure, a few paragraphs on these subjects are 
made introductory to the section on quantitative operations. 

The theories that matter consists of molecules, and that 



PREFACE. IX 

molecules consist of atoms, are freely adopted in this book, 
the author believing that in the present state of knowledge 
and education philosophic conceptions concerning chemistry 
can only be induced in the minds of medical, pharmaceutical, 
and general students by the aid of those theories. 

The chemical notation of the work is in accordance with mod- 
ern views. Equations illustrative of pharmacopceial processes 
have in all important cases a name attached to each formula. 

In the first edition of this Manual, in 1867, chemical nomen- 
clature was modernized to the extent of defining the alkali- 
metal salts and the earthy compounds as those of potassium, 
sodium, ammonium, barium, calcium, magnesium, and alumin- 
ium, instead of potash, soda, ammonia, baryta, lime, magnesia, 
and alumina. The author confidently believes that this 
change, founded on views now adopted by all prominent 
writers on chemistry, will ultimately be accepted by all the 
various followers of medicine and pharmacy. It is a step in 
the direction of simplicity and consistency, and involves far 
less hypothesis than is contained in the old system. The 
name nitrate of potash, for example, was based on the pure 
assumption that nitre contained oxide of potassium or potash 
and nitric anhydride, then erroneously termed nitric acid. By 
the modern name, nitrate of potassium or potassium nitrate, 
all that is intended to be conveyed is that nitre contains the 
element common to all potassium compounds and the group 
of elements common to all nitrates. Under the old method 
students always experienced difficulty in distinguishing salts 
of the metal from salts of its oxide — salts of potassium, for 
instance, from salts of potash ; under the new view no such 
difficulty arises. The contractions in Latin for names like 
11 sulphate of magnesium," magnesii sulphas^ and "magnesium 
sulphate," magnesium sulphuricum, are identical with the con- 
tractions for names resembling " sulphate of magnesia," mag- 
nesise sulphas — an accidental circumstance that will facilitate 
the general introduction of either of the former names among 
the older medical practitioners and pharmacists, and a practical 
advantage that must determine the choice over the latter. 



X PREFACE. 

The author ventures to express some gratification that his use 
and advocacy of this system from 1867 onward resulted in its 
adoption in 1873 in the " Pharmacopoeia of the United 
States," and in 1885 in the " British Pharmacopoeia." Phar- 
macy amongst English-speaking nations will thus sooner or 
later, in the important matter of chemical nomenclature, be 
in accord with the teachings of chemical science. 

Respecting chemical nomenclature generally, the one cha- 
racteristic demanded by the best interests alike of pure and 
of applied chemistry should be permanence. The author 
therefore, whenever possible, has avoided the employment of 
names which include numeral syllables, any doubling or 
halving of atomic weights that the progress of research may 
necessitate at once rendering such names useless, nay, mis- 
leading. Instead of "platinum tetrachloride" he has written 
" platinic chloride '' or " platinum perchloride," and so on. 

The metric system of weights and measures (that which, 
doubtless, is destined to supersede all others) is alone used 
in the sections on quantitative analysis. In other parts of 
the Manual avoirdupois weights and imperial measures are 
employed, necessarily. 

It is hoped that the numerous etymological references scat- 
tered throughout the following pages will be found useful. 
Words in Greek continue to be rendered, by special request, 
in English characters, letter for letter. The word " official " 
is used throughout for things recognized officially by the com- 
pilers of pharmacopoeias ; " officinal," in its original application 
to the officina, or shop— restrictions of meaning which have 
been advocated in every edition of this Manual since 1869, 
and which have been adopted in the recently-issued United 
States Pharmacopoeia. 

Chemical substances recognized in the United States Phar- 
macopoeia, but not in the British Pharmacopoeia, have, never- 
theless, a certain amount of notice in the British editions of 
the Manual, and the chemical substances official in Great 
Britain are noticed in the American editions. The author 
hopes that this slight broadening of the horizon of his readers 



PREFACE. xi 

and students, while enabling him more fully to illustrate 
chemical principles, will perhaps have influence in promoting 
extended as well as concurrent applications of chemistry to 
pharmacy in the great English-speaking countries. 

Students are strongly recommended to test their progress by 
frequent examination. To this end appropriate questions are 
appended to each subject. 

The author's ideal of a manual of chemistry for medical 
and pharmaceutical students is one in which not only the 
science of chemistry is taught, but in which the chemistry 
of every substance having interest for the followers of med- 
icine and pharmacy is noticed at more or less length in pro- 
portion to its importance, and at least its position in relation 
to the leading principles of chemistry is set forth with all 
attainable exactness. The extent to which he has realized 
this ideal he leaves to others to decide. Such a work will 
doubtless in certain parts partake of the character of a diction- 
ary ; but this is by no means a fault, especially if a good index 
be appended, for the points of contact between pure and applied 
chemistry are thus multiplied, and abundant outlets supplied by 
which a lover of the science may pass into other chemical domains 
by aid of other guides, or even into the regions of original re- 
search. Among the rarer alkaloids, bitter bodies, glucosides, salts 
of organic radicals, solid fats, fixed oils, volatile oils. resinSj oleo- 
resins, gum-resins, balsams, and coloring-matters mentioned in 
this volume, will be found many such points whence the ardent 
student may start for the Well-known, the less-known, or the 
untrodden paths of scientific chemistry. 

Within twenty-six years a demand has arisen for fifteen 
large editions of this Manual. The First, in 1867, was in- 
tended as a handbook of practical chemistry only, but the 
notes and remarks made respecting most of the experiments 
were found to be so useful by students that this por- 
tion of the volume was in the .Second Edition (1869) suf- 
ficiently extended to render the book more fairly complete in 
itself. It and all subsequent editions included the chemistry 
of the British Pharmacopoeia. In response to a call from pro- 



xii PREFACE. 

fessional friends in the United States in 1870, the work was 
revised by the author for the followers of Medicine and Phar- 
macy in America, descriptions of the Chemistry of the Prepa- 
rations and Materia Medica of the United States Pharmacopoeia 
being introduced, while those specially British were curtailed, 
and such other adaptations were included as to form a Third 
Edition. A Fourth was presented to English workers in 1872, 
and, founded on the fourth, a Fifth Edition for American stu- 
dents in 1873. A very large Sixth Edition was published in 
England in 1875, and in America a Seventh in 1876, and an 
Eighth in 1879, the Sixth and all following Editions containing 
notices of substances official in Waring's Indian Pharmacopoeia. 
The Ninth, 1881, was an English Edition ; the Tenth, 1883, an 
American ; the Eleventh, 1885, English ; the Twelfth, 1889, 
American ; the Thirteenth, 1889, English. 

The present, Fourteenth. Edition, and the concurrently pro- 
duced Fifteenth, British Edition, contain such alterations and 
additions as seemed necessary for the demonstration of the 
latest developments of chemical principles and the latest ap- 
plications of chemistry to pharmacy. Hence, even if com- 
pared with the immediately preceding editions, on nearly every 
page will be found some indication of the recent rapid growth 
of the science and the art of chemistry. On the other hand, 
synthetical and analytical processes which have become more 
or less superseded have been either omitted or described less 
fully. The whole work has thus been kept within the limits 
of a learner's manual, while the author has endeavored faith- 
fully to portray the present relationship of chemistry to at 
least those areas of medicine and pharmacy with which stu- 
dents should become familiar in the days of their studentship. 
The voluminous Index will maintain the usefulness of the 
book to them afterward in the course of the practice of their 
respective callings. 

The author is indebted to his son Dr. D. Harvey Attfield, 
M. A., D. P. H., Cantab., and to Mr. Charles S. Ellis, for much 
valuable help in preparing this edition for the press. 

17 Bloomsbury Square, London. 



ADVICE TO STUDENTS 
RESPECTING THEIR OBJECT IN STUDYING. 



Avoid studying chemistry, or indeed any subject, merely by 
way of " preparation for examination ;" all ordinary " exam- 
inations " being, admittedly, inefficient tests of competency. 
Do not so mistake the means for the end. You are studying 
to fit yourself for your position in the world. Work dili- 
gently, study thoughtfully and deliberately ; above all, be 
thorough, otherwise your knowledge will be inaccurate and 
transient, and will be unaccompanied by that enlightenment 
of the understanding, that mental training, mental discipline, 
and general elevation of the intellect, which constitute, in a 
word, education. When you are thus educated you will with 
ease and pleasure pass any examination in the knowledge you 
have thus acquired. 

All authorities on education, whether statesmen, teachers, 
or examiners, regard " examinations," even by the most highly 
skilled " Board," with ample time at its disposal and a wide 
area from which to select questions, as but a partial test of 
knowledge and an imperfect test of education. It is the least 
unsatisfactory, however, that has been devised, and is especially 
useful when, following instead of leading education, it is re- 
stricted to the subjects of a well-defined, earnestly followed, 
compulsory public curriculum of study — a curriculum directed 
by a competent representative body, administered by properly 
qualified teachers, and followed by pupils who have had sound 
preliminary training. 

Students ! in all honor and in the highest self-interest take 
care that any inefficiencies inseparable from il examination " are 
abundantly compensated by the extent and precision of your 
knowledge and by the soundness and thoroughness of your 
whole education. 



APPARATUS. 

List of Apparatus for Experiments in Analysis. 
List of apparatus suitable for the three months' course of practi- 
cal chemistry in the summer session of medical schools or for any- 
similar series of lessons — including the preparation of elementary 
gases, analytical reactions of common metals and acidulous radicals, 
analysis of single salts, chemical toxicology, and the examination 
of urine, urinary sediments, and calculi : 
One dozen test-tubes. 
Test-tube stand. 
Test-tube cleaning-brush. 
A few pieces of glass tubing, 
eight to sixteen inches long, 
with a few inches of india-rub- 
ber tubing to fit. 
Small flask. 
Two small beakers. 
Two small funnels. 
Two watch-glasses. 
Two or three glass rods. 
Wash-bottle. 
Small pestle and mortar. 
A 2-pint earthenware basin. 



A 2-inch and a 3-inch evaporat- 

ing-basin. 
Two porcelain crucibles. 
Blowpipe. 
Crucible tongs. 
Round file. 
Triangular file. 
Small retort-stand. 
Sand-tray. 
Wire triangles. 
Platinum wire and foil. 
Test-papers. 
Filter-paper. 
Towel. 

Two dozen corks. 
{This set, packed in a case, can be obtained of any chemical-appara- 
tus maker J or about seven dollars.) 

List of Apparatus for Experiments in Synthesis and Analysis. 
A larger set, suitable for the performance of most of the synthet- 
ical as well as qualitative analytical experiments described in this 
Manual : 



A set of evaporating-basins, of the 

following sizes : 

Two 3-inch-, one 4-inch-, one 6^- 
inch; one 7J-inch; one 8J-inch. 
One retort-stand and three rings. 
Two test-glasses. 
One half-pint flask. 
Half a quire of filter-paper. 
Two porcelain crucibles. 
One measure-glass, 5 oz. 
Blowpipe, 8-inch. 
Two glass funnels. 
One dozen test-tubes (hard glass). 
One test-tube brush. 
One pair of 8-inch brass crucible 

tongs. 

(This set, packed in a case, can be obtained of any chemical-appara- 
fits maker for about twelve dollars.) 

A sponge, towels, and a note-book may be included. 



Two soup-plates. 

One flat-plate. 

Two spatula knives. 

One pair of scissors. 

One round file. 

One triangular file. 

Half a pound of glass rod. 

Half a pound of glass tubing. 

One foot of small india-rubber 

tubing. 
Three dozen corks of various 

sizes. 
Platinum wire and foil. 
Test-papers. 
A nest of three beakers. 



APPARATUS. 



XV 



List of Furniture of a Chemical Laboratory. 

The following apparatus should be ready to hand for students fol- 
lowing an extended course of practical chemistry, in a room set 
apart for the purpose : 



A bench or table and stool. 
Water-supply and waste-pipe. 
A cupboard attached to a chimney 

with an outward draught. 
A furnace fed with coke ; tongs, 

hot-plate or sand-bath, etc. 
A waste-box. 
Shelves for chemical and other 

materials in jars or bottles. 
Gas-supply and lamp with flexible 

tube (or a spirit-lamp and 

spirit). 



Test-tube rack, two dozen holes. 

Iron stand or cylinder for support- 
ing large dishes. 

Iron adapters for fitting dishes to 
cylinder. 

Pestle and mortar, 5 or 6 inches. 

One 6-inch funnel. 

Brown pan, 1- or 2-gallon. 

White jug, 1-gallon. 

Water-bottle, quart. 

■Twenty-eight test-bottles, 6-oz. 



Other articles, such as flasks, retorts, receivers, condensers, large 
evaporating-dishes, may be obtained as wanted. In Quantitative 
Analysis the apparatus described in the sections on that subject will 
be required. 



List of Fluid Reagents. 

Certain chemical substances are used so frequently in analytical 
processes that it is desirable to have small quantities placed in bot- 
tles in front of the operator. (Seep. 18.) As these reagents are 
generally employed in a state of solution, nearly all the solid salts 
may at once be dissolved (in distilled water). The bottles employed 
should be well stoppered, and of 5 or 6 ounces capacity. Common 
glass bottles of this size may be had for about one dollar and a 
quarter per dozen. The bottles should not be more than about 
three-fourths full ; single drops, if required, can then be poured out 
with ease and precision. The following list of test-solutions is 
recommended ; directions for methods of preparing the substances 
not readily purchasable will be found by referring to the Index : 



Sulphuric Acid, strong. 
Nitric Acid, strong. 
Hydrochloric Acid, strong 
Acetic Acid, strong. 



Sol. of Potash, 5 per cent, or U. S. P. 

" Soda, 5 to 15 per cent. 

" Amnion., 10 per cent. or U.S.P. 
Lime-water, saturated. 



The next nine may contain about 10 per cent, of solid salt : 

Ammonium Carbonate, with a Ammonium Sulphydrate. 

little solution of Ammonia Barium Chloride. 

added. Calcium Chloride. 

Ammonium Chloride. Sodium Phosphate. 

Ammonium Phosphate or Arse- Neutral Chromate. 

nate. 



XVI 



SOLID CHEMICAL SUBSTANCES. 



The succeeding seven may have a strength of about 5 per cent : 

Iron Perchloride. 
Silver Nitrate. 



Potassium Ferrocyanide. 
Potassium Ferricyanide. 
Potassium Iodide. 
Ammonium Oxalate. 



Platinum Perchloride. 



Lists op Solid Chemical Substances for Study. 

List of chemical substances necessary for the practical study of the 
non-metallic elements mentioned on pp. 14 to 32. The quantities are 
sufficient for several experiments : 



Potassium Chlorate . . 
Black Manganese Oxide 

Zinc 

Oil of Vitriol 



1 oz. Phosphorus J oz. 

1 oz. Hydrochloric Acid . . . . 1 oz. 

1 oz. Sulphur , J oz. 

2 oz. Iodine i oz. 

List of chemical substances necessary for the analytical study of 

the important metallic and acidulous radicals (pp. 61 to 381). The 
quantities will depend on the frequency with which experiments are 
repeated or analyses performed : those mentioned are sufficient for 
one or two students. The articles are given in the order in which 
they will be required. The eight substances mentioned in the above 
list are included : 



The set of test-solutions described 

in the previous section : 

Potassium Carbonate . . 1 oz. 

Tartaric Acid 1 oz. 

Litmus I oz. 

Magnesium Sulphate . . 1 oz. 

Zinc Sulphate ..... 1 oz. 



Alum 

Ferrous Sulphide 



1 oz, 
1 lb. 



Oak-galls 1 oz. 

Potassium Sulphocyanate . ^ oz. 

White Arsenic i oz. 

Zinc h lb. 

Charcoal . £ lb. 

Ferrous Sulphate .... 1 oz. 

Copper-foil 1 oz. 

Copper Sulphate .... 1 oz. 

Tartar Emetic J oz. 

Mercury I oz. 

Corrosive Sublimate ... J oz. 

Calomel J oz. 



i lb. 

i oz. 

50 grs. 

i oz. 

1 Cr, 



Tin 

Potassium Bicarbonate 



1 oz. 
1 oz. 



Lead Acetate 1 oz. 

Potassium Cyanide . . - \ oz. 
Sodium Hyposulphite . . 1 oz. 

A Lithium Salt 10 grs. 

Strontium Nitrate .... \ oz. 



Black Manganese Oxide 
Manganese Chloride . . 
Cobalt Chloride .... 
Nickel Nitrate .... 
Chromium Chloride . , 

Gold-leaves 2 or 3 

Cadimum Chloride ... \ oz 
Bismuth Nitrate . . . . \ oz 
Potassium Bromide ... \ oz 

Starch . . 1 oz 

Potassium Nitrate .... 1 oz 
Copper borings or turnings 1 oz 

Indigo loz 

Potassium Chlorate 

Iodine 

Spirit of Wine 1 oz 

Sulphur 1 oz 

Acid Potassium Oxalate . 1 oz 

Citric Acid 1 oz 

Phosphorus 1 oz 

Borax . , . 1 oz 

Turmeric \ oz 

Benzoic Acid 50 grs 

Fluor Spar 1 oz 

Tannic Acid . . ... 50 grs 

Gallic Acid 50 grs 

Pyrogallic Acid 50 grs 



1 oz. 
\ oz. 



CHEMICALS. XV11 

The quantities of materials required for the study of chemistry 
synthetically will necessarily vary with the desires and tastes of the 
operator or according to the number and requirements of students 
working together, 

The materials that will be needed for the home-study of organic 
chemistry will vary with the requirements of the student. By the 
time he has qualified himself for a preliminary experimental course 
in that section of the science he may trust largely to his own judg- 
ment as regards both materials and apparatus. 



CONTRACTIONS USED IN THIS MANUAL. 

B. P., British Pharmacopoeia. I F., Fahrenheit. 



U. S. P., United States Pharma- 
copoeia. 
C, Centigrade, 
cc, Cubic centimetres. 



grm., Gramme. 

mm., Millimetre. 

T.S., Test solution, U.S. P. 

V. S., Volumetric solution, U. S.P. 



CONTENTS 



PAGE 

Preface c . . . . v 

Advice to Students xiii 

Lists of Apparatus xiv 

List of Furniture of a Chemical Laboratory xv 

List of Fluid Reagents xv 

Lists of Solid Chemical Substances for Study xvi 

Introduction * 13 

General Properties of the Non-metallic Elements ... 15 

Symbols and Derivation of Names of Elements 31 

The General Principles of Chemical Philosophy .... 35 
Common Metallic Elements, their Official Preparations 
and Tests: 
Salts of Potassium, Sodium, Ammonium, Barium, Calcium, 
Magnesium, Zinc, Aluminium, Iron, Arsenum, Antimony, 

Copper, Mercury, Lead, Silver GO 

Analytical Charts for Ordinary Metals 224 

Rarer Metallic Elements, their Official Preparations 
and Tests : 
Salts of Lithium, Strontium, Manganese, Cobalt, Nickel, 
Chromium, Tin, Gold, Platinum, Cadmium, Bismuth . 22G 

Analytical Charts for all Metals 250 

Common Acidulous Radicals, Official Acids, and Tests: 
Chlorides, Bromides, Iodides, Cyanides, Nitrates, Chlorates, 
Acetates, Sulphides, Sulphites, Sulphates, Carbonates, Oxa- 
lates, Tartrates, Citrates, Phosphates, Borates 202 

Salts of Rarer Acidulous Radicals: 

Benzoates, Cyanates, Formates, Hippurates, Ferrocyanides, 
Ferricyanides, Fluorides, Hypophosphites, Hyposulphites, 
Lactates, Malates, Meconates, Metaphosphates, Nitrites, 
Phosphites, Pyrophosphates, Silicates, Sulphocyanates, 

Tannates, Gallates, Urates, Valerianates 335 

xix 



XX CONTENTS. 

PAGE 

Analytical Chart for Acidulous Radicals 369 

Systematic Analysis . 370 

Organic Chemistry , 383 

Chemical Toxicology 561 

Examination of Morbid Urine and Calculi 572 

Official Galenical Preparations 589 

Official Chemical Preparations 591 

Quantitative Analysis : 

Introductory Remarks . , 591 

Determination of Atmospheric Pressure ........ 593 

Determination of Temperature 594 

Determination of Weight 600 

Weights and Measures 600 

Specific Gravity ,.......' 613 

Correction of the Volume of Gases for Pressure 

and Temperature , . 619 

Volumetric Quantitative Analysis 625 

Gravimetric Quantitative Analysis 659 

Dialysis . 704 

Appendix : 

Table of Tests for Impurities in Preparations of the 

United States Pharmacopoeia 707 

Saturation Tables . ■■ 724 

The Elements, their Symbols, and Atomic Weights . . 725 

Index . 727 



CHEMISTRY: 

GENERAL, MEDICAL, AND PHARMACEUTICAL. 



INTRODUCTION* 

Man can neither create matter nor destroy matter ; he can only 
alter its form — alter the relation of its elements to each other, 
or note similar alterations proceeding within and around him in 
Nature. To study those alterations in all their known length 
and breadth and depth is to study Chemistry. 

The infinite varieties of solid, liquid, and gaseous matter of 
which our earth and atmosphere are composed may be resolved, 
with more or less difficulty, into a very few distinct substances 
appropriately termed " elements," for by no known means can 
they be further decomposed. About seventy of these elements 
have been proved to exist. Some (such as gold) occur natu- 
rally in the uncombined state, but the greater number are com- 
bined in so subtle a manner as to conceal them from ordinary 
methods of observation. Thus, none of the common proper- 
ties of water indicate that it is composed of two elements, both 
gases, but differing much from each other: nor can the senses 
of sight, touch, and taste, or other common means of examina- 
tion, detect in their concealment the three elements of which 
sugar is composed. The art by which these and all other coin- 
pound substances are resolved into their elements is termed 
Chemistry, a name derived possibly from the Arabic word 
kamai, to conceal. f The art of Chemistry also includes the 

: Students using this book as a guide in following Chemistry practi- 
cally should read the first four pages, and then commence work by pre- 
paring oxygen. All students should read the prefatory pages, especially 
the page of " Advice to Students." 

t The idea that common metals contained valuable metals concealed 
within them was the one seed from which mainly sprung chemical 
knowledge. The men who endeavored to find the secret of such con- 
cealment were appropriately termed alchemists, and their efforts spoken 
of as alchemy (al himia, from hamai, to conceal). Their persistent labors, 
generation after generation, were unsuccessful so far as the transmuta- 
tion of baser metals into gold was concerned, yet were invaluable topos- 

2 13 



14 DEFINITIONS. 

construction of compounds from elements, and the conversion 
of substances of one character into those of another. The gen- 
eral principles or leading truths relating to the elements, to the 
manner in which they severally combine, and to their proper- 
ties when combined — that is, to the properties of the compound 
substances formed by their union — constitute the science of 
Chemistry.* 

From these few words concerning the nature of the art and 
science of Chemistry it will be seen that in most of the occu- 
pations that engage the attention of man Chemistry plays an 
important part — in few more so than in the practice of thera- 
peutics f and of pharmacy. J 

terity, for new substances were discovered and truths of nature unveiled : 
from these discoveries multiplication of discoveries resulted, and thus 
grew the still growing branch of knowledge called Chemistry. 

* Persons who practise the art and science of Chemistry are known 
as chemists. Some two hundred or more years ago, and before Chem- 
istry was a science, the only " chemists " were the makers and vendors 
of chemical substances, then only used as medicines. They were the 
successors of the alchemists. In Great Britain these chemists and the 
herb-dealers, otherwise drug-grocers, otherwise drug-gists, gradually 
associated to form the " chemist and druggist." Between the " chemist 
and druggist " and the physician there existed the apothecary — the put- 
ter together of medicines or compounder of physicians' prescriptions. 
The apothecary has since become a medical practitioner, prescriptions 
being now " made up " by the chemist and druggist. The latter in Great 
Britain, since the year 1868, has the title of chemist and druggist, his higher 
title being pharmaceutical chemist ; these respective designations he legally 
assumes on passing the minor and major examinations conducted by the 
Pharmaceutical Society of Great Britain, in accordance with the pro- 
visions of the Pharmacy Acts of 1852 and 1868. The whole class is often 
spoken of as that of pharmacists or pharmaceutists, terms also used in the 
United States. Other classes of chemists are the analytical chemists, 
who give special attention to analysis ; manufacturing chemists, who 
restrict their labors to the preparation of chemical substances ; while 
others devote a portion of their knowledge and energies to chemical 
education or to chemical research, or are appealed to as consulting chem- 
ists by the persons, firms, corporations, or governments needing chemical 
advice respecting industrial processes, hygienic matters, etc. The call- 
ings of the consulting and analytical chemists are generally united, and 
the professional gentlemen who follow these conjoint avocations also not 
infrequently occupy professorial or other tutorial positions, sometimes 
adding to these labors more or less work at original chemical research. 
In England, Scotland, and Ireland, nearly all the leading professional 
chemists are Fellows of the Institute of Chemistry of Great Britain and 
Ireland. 

| Therapeutics (0epa7revTiKo?, therapeutikos, from 6epairevu>, therapeuo, I 
nurse, serve, or cure) is that branch of medicine which treats of the 
application of remedies for diseases. The therapeutist also takes cog- 
nizance of hygiene — that department of medicine which respects the 
preservation of health — and of dietetics, the subject of diet or food. By 
pharmacology is understood the normal action of drugs upon the system 
as underlying the therapeutic action. — Physics, see p. 38. 

X Pharmacy (from 4>dpi*aKov, pharmaTcon, a drug) is the generic name for 



THE ELEMENTS. 15 

Air, water, food, drugs, and chemical substances — in short, all 
material things — are composed, as stated, of elements. An 
intimate knowledge of the properties of the more important 
elements, both in the free and in the combined state, and of the 
various substances they form when they have combined with 
each other, some knowledge or idea of the power or force (the 
chemical force or chemical affinity) by which the elements con- 
tained in the compounds are held together, and an application 
of such knowledge to pharmacy and medicine, must be the 
objects sought to be attained by the learner, for whom especially 
this book has been written. 



The Elements. — Of the seventy or so known elements, about 
forty are of medical or pharmaceutical interest ; of these, two- 
thirds are metals and one-third non-metals ; the remainder* are 
so seldom met with in Nature as to have received no practical 
application either in medicine, art, or manufacture. Before 
intimately studying the elements it is desirable to acquire some 
general notions concerning them : such a procedure will also 
serve to introduce the practical student to his apparatus, and 
make him better acquainted with the various methods of man- 
ipulation. f 

Metallic Elements. — With regard to the metallic elements it 
may safely be assumed that the reader has sufficient knowledge 
for present purposes ; but little, therefore, need now be said 
respecting them. He has an idea of the appearance, relative 
weight, hardness, etc. of such metals as gold, silver, copper, 
lead, tin, zinc, and iron. If he has not a similar knowledge of 
mercury, antimony, arsenium, platinum, nickel, aluminium, 
magnesium, potassium, and sodium, he should embrace the ear- 

the operations of preparing or compounding medicines, whether per- 
formed by the medical practitioner or by the chemist and druggist. It 
is also sometimes applied, like tbe corresponding term surgery, to the 
apartment in which the operations are conducted. Pharmacognosy is the 
study of the crude drugs of the vegetable and animal kingdom. 

* A list of the elements will be found at the end of the volume. 

t This allusion to apparatus need not discourage the youngest pupil. 
With the aid of a few phials, wine-glasses, or other similar vessels always 
at hand, he may, by studying the following pages, learn the chemical 
reactions which are constantly occurring in the course of making up 
medicine, understand the processes by which medicinal preparations are 
manufactured, and detect adulterations, impurities, or faults of manu- 
facture. Among the substances used in medicine will be found nearly 
all the chemical materials required. If, in addition, a dozen test-tubes 
and a few feet of glass tubing be procured, many of the experiments 
described may be performed. For full lists of apparatus and chemical 
material see the introductory pages. 



16 NON-METALLIC ELEMENTS. 

liest opportunity of seeing and handling specimens of each of 
these metals. 

Non-Metallic Elements, wrongly termed Metalloids. — With 
regard to the non-metallic elements it is here supposed that the 
student has no general knowledge. He should commence his 
studies, therefore, by a series of operations as follows on eight 
of their number : 

OXYGEN. 

Preparation. — Oxygen is the most abundant element in nature, 
forming (in a state of combination) about one-half of the whole 
weight of our globe. To obtain it for experimental purposes all 
that is necessary is to apply heat — that force which will often be 
noticed as antagonistic, so to speak, to chemical union ; heat gen- 
erally separating particles of matter farther from each other, while 
chemical attraction tends to bind them closer together — to heat cer- 
tain compounds containing oxygen ; the latter is then evolved in its 
normal, natural gaseous condition. Several substances when heated 
yield oxygen ; but for convenience of students the crystalline body 
known as potassium chlorate is best fitted for the experiment. The 
size and form of the vessel in which to heat it will mainly depend 
on the quantity required, but for the purposes of the student the 
best is a test-tube, an instrument in constant requisition in studying 
practical chemistry. It is simply a tube of thin glass, a few inches 
in length and half or three-quarters of an inch in diameter, closed 
by fusion at one end. It is made of thin glass, in order that it may 
be rapidly heated or cooled without risk of fracture. (See Tigs. 3 
and 4.) 

Outline of the Process. — Heat potassium chlorate (say as 
much as will lie on a shilling) in a test-tube by means of a 
spirit or gas flame ; gaseous oxygen is quickly evolved. Before 
applying heat, however, provision should be made for collecting 
the gas. 

Collection of Gases (see Fig. 3). — Procure a piece of glass 
tubing about the thickness of a quill pen and afoot or eighteen 
inches long, and fit it to the test-tube by means of a cork in the 
following manner (longer tubes may be neatly cut to any size 
by smartly drawing the edge of a triangular file across the glass 
at the required point, then clasping the tube, the scratch being 
between the hands, and pulling the portions asunder, force 
being exerted in a slightly curved direction, so as to open out 
the crack which the file has commenced) : The tube is fixed in 
the cork through a round hole made by the aid of a red-hot 
wire, or, better, by a rat-tail file, or, best of all, by one of a set 
of cork-borers — pieces of brass tubing sharpened at one end 
and having a flat head at the other. Fit the cork and test-tube 



OXYGEN. 



17 



to each other accurately and closely, but not so tightly as to 
break the test-tube. Setting aside the test-tube for a few min- 
utes, proceed to bend the long piece of tubing to the most 
convenient shape for collecting the gas. 

To Bend Glass Tubes. — Hold the part of the tube required 
to be bent in any gas or spirit flame (a fish-tail gas-jet, for 
example, Fig. 1), constantly rotating it, so that about an inch 
of the glass becomes heated. It will soon be felt to soften, 



Fig. 1. 




Softening and Bending Glass Tubes. 



and will then, yielding to the gentle Fig. 2. 

pressure of the fingers, assume any 

required angle. In the present case 

the tube should be heated at about 

four inches from the extremity to 

which the cork is attached, and bent 

to an angle of 90 degrees (Fig. 2). 

Source of Heat. — The source of heat 
for the test-tube may be the flame of an 
ordinary spirit-lamp, or, still better where 
coal-gas is procurable, a mixture of the 
latter with air. Gas-lamps, especially 
constructed to burn a mixture of coal-gas 
and air, are sold by chemical-apparatus 
manufacturers. (See Figs. 3 and 7.) 

Collection, etc. (continued). — Fit the 
cork and bent tube into the test-tube ; 
the apparatus will then be ready for delivering gas at a 
convenient distance from the heated portion of the arrange- 
ment. To collect it, have ready three or four test-tubes (or 
small wide-mouthed bottles) filled with water, and inverted 
in a basin or other vessel, also containing water, taking care to 
keep the mouths of the still full tubes a little below the sur- 
face. Now apply heat to the chlorate contained in the test- 
tube, and so arrange the open end of the bent tube under the 
water, that the gas, which presently escapes with effervescence 
from the melted chlorate, may pass out from the free end of the 
tube, and may bubble into and gradually fill the previously 




18 



NON-METALLIC ELEMENTS. 



water-filled inverted test-tubes. The first tubeful may be 
rejected, as it probably consists of little more than the air 

Fig. 3. 





This engraving represents the preparation, collection, and storage of small quan- 
tities of oxygen gas. A test-tube and bent glass tube, joined together by a perfor- 
ated cork, are supported by the arm of an iron stand. (The apparatus might, be 
held by the fingers.) The tube is heated by a gas-lamp. (The spirit-lamp shown at 
back might be used instead.) Gas evolved from the heated substance in the test- 
tube is displacing water from an inverted test-tube. Spare tubes in a test-tube rack 
are at hand, and tubes already filled are set aside till wanted. A nest of cork- borers, 
a round file, a triangular file, and a test-tube cleaning brush are lying on the table 
or student's bench. Below are cupboards for apparatus ; above are bottles contain- 
ing testing liquids, etc. 

originally in the apparatus, and which has been displaced by 
the oxygen. That which comes afterward will be pure oxygen. 



OXYGEN. 19 

As each tube or bottle becomes full, close its mouth (still 
under the surface of the water) by a cork, and then set it 
aside ; or a little cup (such as a porcelain crucible or small 
gallipot) may be brought under the mouth, and the cup, with 
the mouth of the tube in it, be lifted out of the water and 
placed close by till wanted, the water remaining in the cup 
effectually preventing the gas from escaping. 

On the large scale, oxygen may be made in the same way, larger 
vessels (glass flasks or iron bottles) being employed. Less heat also 
will be necessary if the potassium chlorate be previously mixed 
with very fine sand, or, still better, with about an equal weight of 
common black manganese oxide. 

Note on the Collection and Storage of Gases. — It may be as well 
to state that nearly all gases, whether for experimental or practical 
purposes, are collected and stored in a similar manner. Even coal- 
gas is generated at gas-works in iron retorts very much the shape of 
test-tubes, only they are as many feet long as a test-tube is inches, 
and the well-known gigantic gas-holders may be viewed as inverted 
iron test-tubes of great diameter. 

Properties. — Free oxygen is a colorless gas. Cailletet and 
Pictet succeeded in liquefying it, and Wroblewski and Obszewski 
have obtained it in some amount as a definite, colorless, trans- 
parent fluid. Air, which contains 20 per cent, of oxygen, has 
been solidified, but not yet the pure oxygen itself. Obviously, 
it is not very soluble in water, or the gas could not be collected 
by the aid of that liquid. Oxygen is soluble to a certain ex- 
tent, however (about 3 volumes in 100 at common tempera- 
tures), or fishes could not breathe. Other noticeable negative 
features are its want of taste and smell. 

To show the relation of oxygen to combustion, remove one 
of the tubes from the water by placing the thumb over its 
mouth, and apply for a second a lighted wood match to the ori- 
fice ; the gas will be found to be incombustible. Extinguish the 
flame of the match, and then quickly introduce the still incan- 
descent carbonaceous extremity of the wood halfway down the 
test-tube ; the wood will at once burst into flame, owing to the 
extreme violence with which oxygen gas supports combustion. 
These tests of the presence of free oxygen may also be applied 
at the extremity of the delivery-tube whilst the gas is being 
evolved. (It is desirable to retain two tubes of the gas for use 
in subsequent experiments ; also one tube in which only one- 
third of the water has been displaced by oxygen.) 

Relation of Oxygen to Animal and Vegetable Life. — Not only the 
carbon at the end of a piece of charred wood, but any other sub- 



20 NON-METALLIC ELEMENTS. 

stance that will burn in air (which, as will be seen presently, is 
diluted oxygen), will burn more brilliantly in pure oxygen. The 
warmth of the bodies of animals is kept up by the continuous 
burning of the tissues in the oxygen (of the air) drawn into the 
system through the lungs. The product of this combustion is ex- 
haled into the air as a gaseous compound of carbon and oxygen 
termed carbonic acid gas — a gas which in sunlight is absorbed by 
and decomposed in the cells of plants, with fixation of the carbon 
and liberation of the oxygen ; hence the atmosphere is kept con- 
stant in composition. 

Memorandum. — At present it is not advisable that the reader 
should trouble himself with the consideration of the chemical 
action which occurs either in the elimination of oxygen from its 
compounds or in the separation of any of the following non-metal- 
lic elements from their combinations. It is to the properties of 
those elements themselves, especially in their free and least active 
condition, that he should at present restrict his attention. Work- 
ing thus from simple to more complex facts, he will in due time 
find that the comprehension of such actions as occur in the prep- 
aration of these few elements will be easier than if he attempted 
their full study now. 

HYDROGEN. 

Preparation and Collection. — The element hydrogen is also, 
in the free state, a gas * and is obtainable from its commonest 
compound, water (of which one-ninth by weight is hydrogen), 
by the agency of hot zinc or iron, but more conveniently by 
the action of either of those metals on cold diluted sulphuric 
acid. The apparatus used for making oxygen may be employed 
for this experiment, but no lamp is required. Place several 
pieces of thin zincf in the generating-tube (Fig. 4), or in any 
common glass bottle (Fig. 5) or flask, and cover them with 
water. The collecting-tubes (these also may be wide-mouthed 
bottles) being ready, add strong sulphuric acid (oil of vitriol) 

* Graham obtained alloys of hydrogen with palladium and other 
metals, compounds in which several hundred times its bulk of gas is 
retained by the metal in vacuo or even at a red heat. This was physical 
confirmation of the opinion long held by chemists, that hydrogen is a 
gaseous metal. Graham termed it hydrogenium, other chemists hydrium, 
arid considered its relative weight in the solid state to be nearly three- 
fourths that of water. Cailletet and Pictet have since actually liquefied 
and solidified this element. 

f The best form is granulated zinc {Zincum, U. S. P.), made by heating 
scraps of common sheet zinc in an iron ladle over a fire, and, immediately 
the metal is fused, pouring it, in a slow stream, into a pail of water from 
a height of eight or ten feet. Each drop of zinc thus yields a thin little 
bell, which, for its weight, presents a large surface to the action of the 
acid liquid. If the zinc is allowed to become hotter than necessary, the 
little bells will not be formed. A trace of iron in the zinc greatly in- 
creases the rate at which the hydrogen is evolved. 



HYDROGEN. 



21 



to the zinc and water, in the proportion of about 1 volume of 
acid to 5 of water, and fit on the delivery -tube ; or pour the 
acid down such a funnel-tube* as is shown in Fig. 5; the 



Fig. 4. 



Fig. 5. 




Preparation of Hydrogen. 

hydrogen at once escapes with effervescence from the fluid. 
Having rejected the first portions (or having waited until the 
air originally in the bottle may be considered to be all expelled), 
collect four or five tubes of the gas in the manner described 
under Oxygen. 

Note. — This process is similar to that of the " British Pharma- 
copoeia." In making larger quantities bottles' of appropriate Bize 
may be employed. Other metals, notably potassium and sodium, 
liberate hydrogen the moment they come into contact with water, 
but the processes are not economical and the action is dangerously 
violent. 

Properties. — Like oxygen, hydrogen gas is invisible, inodor- 
ous, and tasteless. If iron be used, the gas has a marked 
smell, but this is due to impurities derived from the iron. 

Apply a flame to the mouth of the delivery-tube as soon as 
the operator's judgment tells him that the brisk effervescence 
of hydrogen must have resulted in the driving out of all air 
from the tube, for the mixture of hydrogen and air may explode. 
Ignition of the hydrogen gas ensues, showing that, unlike oxy- 
gen gas, it is combustible. 

Plunge a lighted match well into a tube (or wide-mouthed 
bottle) containing free hydrogen : the gas is ignited, but the 
match becomes extinguished. This shows that hydrogen is not 
a supporter of combustion. 



* Funnel-tubes may be purchased of the apparatus-maker, or, if the 
pupil has access to a table blowpipe and the advantage of a tutor to 
direct his operations, they may be made by himself. 
2* 



22 NON-METALLIC ELEMENTS. 

Hydrogen gas in burning unites with the oxygen of the air 
and forms water, which may be condensed on a cool glass or 
other surface. Prove this by holding a glass vessel a few 
inches above a hydrogen flame. In burning the hydrogen 
contained in one of the tubes or bottles the flame is best seen 
when the tube is held mouth upward and water poured in so as 
to expel the gas gradually. 

If, instead of this gradual combination of the two elements 
oxygen and hydrogen, they be mixed together in bulk in the 
right proportions and then ignited, they will rapidly combine, 
and explosion will result. Prepare a mixture of this kind by 
filling up with hydrogen a test-tube from which one-third of 
the water has been expelled by oxygen. Remove the tube 
from the water, placing a finger over the mouth, and, having 
a lighted match ready, apply the flame ; explosion ensues, 
owing to the instantaneous combination of the whole bulk of 
the two elements and the expansive force of the highly heated 
steam produced. If anything larger than a test-tube is em- 
ployed in this experiment, it should be a soda-water bottle or 
some such vessel equally strong. 

Notes. — These gases thus unite at a temperature far higher than 
that of boiling water, 2 volumes of hydrogen and 1 of oxygen yield- 
ing 2 of gaseous water (true steam). 

The noise of such' explosions is caused by concussion between the 
suddenly expanded gaseous body and the air. 

The force of the explosion — or, in other words, the force of the 
suddenly heated and therefore suddenly expanded steam — is below 
that necessary to break the test-tube. Some force, however, is 
exerted ; and hence the necessity of the precaution previously sug- 
gested, of allowing all the air which may be in a hydrogen appa- 
ratus to escape before proceeding with the experiments. If a flame 
be applied to the delivery-tube before all the air is expelled, the 
probable result will be ignition of the mixture of hydrogen and 
oxygen (of the air) and consequent explosion. But even in this 
case the generating vessel is not often fractured, unless it be large 
and of thin glass, the ordinary effect being that the cork is blown 
out and the delivery-tube broken on falling to the ground. 

Hydrogen is a constituent of all the substances used for produ- 
cing artificial light, such as solid fats, oil, and coal-gas. The ex- 
plosive force of large quantities, such as a roomful, of coal-gas and 
air, though vastly below that of an equal weight of gunpowder, is 
well known to suffice for blowing out that side of the room which 
offers least resistance. 

The composition of water can be proved analytically as well as 
synthetically, a current of electricity decomposing it, by " electro- 
lysis" (Tivu, luo, I loose, or I decompose), into its constituent 
twice as much hydrogen as oxygen by volume being produced. 



HYDROGEN. 



23 



Combustion (from comburo, I burn). — The experiments with 
hydrogen and oxygen illustrate the true character of combustion. 
Whenever chemical combination is sufficiently intense to be accom- 
panied by heat and light, the materials are said to undergo com- 
bustion. Combustion only occurs at the line of contact of the com- 
bining bodies ; a jet of oxygen will burn in an atmosphere of 
hydrogen quite as easily as a jet of hydrogen in oxygen. A jet of 
air (diluted oxygen) will burn as readily in a jar of coal-gas as a 
jet of coal-gas burns in air ; each is combustible, each supports the 
combustion of the other. Hence the terms combustible and sup- 
porter of combustion are purely conventional, and only applicable 
so long as the circumstances under which they are applied remain 
the same. In the case of substances burning in air the conditions 
are, practically, always the same ; hence no confusion arises from 
regarding air as the great supporter of combustion, and bodies 
which burn in it as being combustible. 



Fig. 6. 



Fig. 7. 




Structure of Flames. 



Bunsen." or Air-Gas. Burner. 



Structure of Flame.— A candle flame (Fig. G) or oil flame is a jet 
of gas intensely heated; the central portion is unburntgas; the 

next envelope is formed of partially burnt and very dense gaseous 
and solid particles sufficiently highly heated to give light; and the 
outer cone of completely burnt gases. In the figure the sharp- 
ness of limit of these cones is purposely somewhat exaggerated. 
Air made by any mechanical contrivance to mix with the gas in the 
interior of a flame at once burns up, or perhaps prevents the for- 
mation of, dense gases, giving a hotter but non-luminous jet. The 
air-gas lamps (Fig. 7), or " Bunsen " gas-burners, commonly used 
in chemical laboratories, are constructed On this principle: their 
flame has the additional advantage of not yielding a deposit of 
soot. 

In the air-gas lamp coal-gas escaping from a, small orifice draws 
rather more than twice its volume of air (supplied through adjacent 
holes) into its column, and the mixture of gas and air passes upward 



24 NON-METALLIC ELEMENTS. 

along a pipe. It only burns at the end, and not within the pipe, 
partly because the metal of the burner, by conducting heat away, 
cools the mixture below the temperature at which it can ignite ; 
partly because the velocity with which the mixture flows out is 
greater than the rate at which such a mixture ignites ; and partly 
because the proportion of air to gas in the mixture is insufficient for 
perfect combustion, the external air contributing materially to the 
complete combustion of the jet of air-gas. The Davy safety-lamp 
acts on the principle first named : a wire-gauze cage surrounds an 
oil flame ; an inflammable mixture of gas (fire-damp) and air can 
pass through the gauze and catch fire . and burn inside ; but the 
flame cannot, ordinarily, be communicated to the mixture outside, 
because the metal of the gauze and of the other parts cools down the 
gas below the temperature at which combustion can continue. 

Properties (continued'). — Gaseous hydrogen is the lightest 
substance known. It was formerly used for filling balloons, 
but was superseded by coal-gas, because coal-gas, though not 
lighter, is cheaper and more easily obtained. The lightness of 
hydrogen may be rendered evident by the following experi- 
ment : Fill two test-tubes with the gas, and hold one with its 
mouth downward and the other with its mouth upward. The 
hydrogen will have escaped from the latter in a few seconds, 
whereas the former will still contain the gas after the lapse of 
many seconds. This may be proved by applying a lighted 
match to the mouths. 

The relative iveight or specific gravity of oxygen is sixteen times 
that of hydrogen. A vessel holding 1 grain of hydrogen will hold 
16 grains of oxygen. The relation of the weight of hydrogen to 
air is as 1 to 14.44, or as 0.0693 to 1.0. 1 grain of hydrogen by 
weight would measure about 27 fluidounces, and therefore would 
about fill a common wine-bottle. Such a bottle would, at ordinary 
temperatures, hold about 14J grains of air or 16 grains of oxygen. 

Mem. — It is desirable to retain two tubes of hydrogen for use in 
subsequent experiments. 

Diffusion of Gases. — Hydrogen gas cannot be kept in such ves- 
sels as the* inverted test-tube, for, though much lighter than air, it 
diffuses downward into the air, while the air, though much heavier, 
diffuses upward into the hydrogen. This power of diffusion is 
characteristic of all gases, and proceeds according to a fixed rate — 
namely, " in inverse proportion to the square root of the specific 
gravity of the gas 1 ' (Graham). Thus hydrogen diffuses four times 
faster than oxygen. This great and important property of diffusion 
strongly suggests that the particles of gases, at least, are always 
moving, never at rest ; how otherwise could gases diffuse into each 
other as they do, notwithstanding the opposing influence of gravita- 
tion ? Diffusion strongly supports this (Clausius's) kinetic (atveG), 
kineo, I move or put in motion) theory of the physical condition of 
gases. 



NITROGEN. 25 

PHOSPHORUS. 

Appearance and Source. — Phosphorus {Phosphorus, IT. S. P.) is 
a solid element, in appearance and consistence resembling white 
wax, but it gradually becomes yellow by exposure to light. It is a 
characteristic constituent of bones, and may be prepared from bones 
by a process which will be described subsequently. 

Caution. — Phosphorus, on account of its great affinity for oxygen, 
takes fire very readily in the air, and should therefore be kept under 
water. When wanted for use it must be cut under water. It is 
employed in tipping lucifers, though red or amorphous phosphorus 
{vide Index) is less objectionable for this purpose. 

Experiment. — Dry a piece about one-fourth the size of a pea 
by quickly and carefully pressing it between the folds of 
porous (filter- or blotting-) paper ; place it on a plate, and 
ignite by touching it with a piece of warm wire or wood. The 
product of combustion is a dense white suffocating smoke, 
which must be confined at once by placing an inverted tumbler, 
or beaker, or other similar vessel over the phosphorus. The 
fumes rapidly aggregate, and fall in white flakes on the plate. 
When this has taken place and the phosphorus is no longer 
burning, moisten the powder with a drop or two of water, and 
observe that some of the water is converted into steam, an 
effect due to the intense affinity with which another portion of 
the water and the powder have combined, yielding heat. 

The powder produced by the combustion of phosphorus is termed 
phosphoric anhydride ; the combination of the latter with the ele- 
ments of water produces a variety of phosphoric acid which dis- 
solves in the water, forming, on standing, a dilute solution of ordi- 
nary phosphoric acid. The diluted phosphoric acid of the British 
and American Pharmacopoeias is a similar solution, made in a some- 
what different way and of definite strength. 

NITROGEN. 

Source. — The chief source of this gaseous element is the atmo- 
sphere, nearly four-fifths of which consists of nitrogen (the remaining 
fifth being almost entirely oxygen). 

Preparation. — Burn a piece of dried phosphorus, the size of 
a pea, in a confined portion of air. The oxygen gas is thus 
removed, and the nitrogen gas remains. The readiest mode of 
performing this experiment is to fix a piece of earthenware 
(the lid of a small porcelain crucible answers very well) on a 
thin piece of cork, so that it may float in a dish of water 
(Fig. 8). Place the phosphorus on the lid, ignite with a warm 
rod. and then invert a tumbler or any glass vessel of about a 
half-pint capacity over the burning phosphorus, so that the 



26 



NON-METALLIC ELEMENTS. 



mouth of the glass may dip into the water. Let the arrange- 
ment rest for a short time, for the fumes of phosphoric anhy- 
dride to subside and dissolve in the water, and then decant the 
gas into test-tubes as indicated in Fig. 9, using a tub or other 
vessel of water of sufficient depth to admit of the glass con- 
taining the nitrogen gas being turned on one side without air 



Fig. 



Fig. 9. 




Preparation of Nitrogen. 



Decantation of Gases. 



Larger quantities of nitrogen gas are obtained in the same way. 
Other combustibles, as sulphur or a candle, might be used to burn 
out the oxygen gas from the air, but none answers so quickly and 
completely as phosphorus •, added to which the product of their com- 
bustion would not always be dissolved by water, but would remain 
with the nitrogen. 

Mem. — The statement concerning the composition of the air is 
roughly confirmed in isolating nitrogen, about one-fifth of the vol- 
ume of the air originally in the glass vessel having disappeared, its 
place being occupied by water. 

Properties. — Like oxygen and hydrogen, nitrogen gas is 
invisible, tasteless, and inodorous. By pressure, Cailletet and 
Pictet condensed it to a liquid. Wroblewski and Oboszewski 
obtained it in some amount as a definite, colorless, transparent 
fluid, which congeals, by its own evaporation, to a white snow- 
like solid. It is only slightly soluble in water. Free nitrogen 
is distinguished from all other gases by the absence of any very 
characteristic or positive properties. Apply a flame to some 
contained in a tube ; it will be found to be incombustible. 
Immerse a lighted match in the gas ; the flame is extinguished, 
showing that nitrogen is a non-supporter of combustion. 

Nitrogen is fourteen times as heavy as hydrogen. 
The chief office of the free nitrogen in the air is to dilute the ener- 
getic oxygen, a mere mechanical mixture resulting. 



CHLORINE. 27 

The air is nearly fourteen and a half (14.44) times as heavy as 
hydrogen. It may be liquefied and, apparently, solidified. Its 
average composition, including minor constituents (which will be 
referred to subsequently), is as follows : 

Composition of the Atmosphere. 

In 100 volumes. 

Oxygen 20.61 

Nitrogen 77.95 

Carbonic acid gas 04 

Aqueous vapor 1.40 

Nitric acid . , j 

Ammonia \ traces. 

Carburetted hydrogen J 

Sulphuretted hydrogen | traces in 

Sulphurous acid j towns. 

Pure dry air free from carbonic acid invariably contains, by weight, 
23 parts of oxygen to 77 of nitrogen, or, by volume, 20.76 parts of 
oxygen to 79.24 of nitrogen. Ozone {vide Index) is said to be a nor- 
mal constituent of air. 

Free Nitrogen and Combined Nitrogen. 
The comparative inactivity or negative character of nitrogen in 
its free condition — that is, when uncombined with other elements — 
contrasts strongly with its apparent influence in a state of combina- 
tion. When its compounds with hydrogen come to be studied, it 
will be found to be, apparently, the chief or leading, or, in a sense, 
the most important, element of those compounds — the ammoniacal 
compounds. United with carbon, it gives the poisonous cyanic sub- 
stances. With oxygen it yields quite a large group of bodies, 
amongst which are the common and important class of salts termed 
nitrates. With carbon, as well as hydrogen and some oxygen, it 
affords powerful agents termed alkaloids — near relatives of ammo- 
nia ; while the same elements otherwise grouped, and sometimes a 
little sulphur or phosphorus, form the various albumenoid and 
gelatinoid matters characteristic of the tissues of animals and vege- 
tables. In a perfect structure we should perhaps scarcely regard 
any one element or member as more important than another ; still, 
such a conclusion almost forces itself upon us as Ave become 
acquainted with the chemical history of combined nitrogen. Free 
nitrogen is not, however, altogether inactive, for the nitrogen of the 
air appears to be absorbed and assimilated by plants, a given crop 
containing more nitrogen than the soil and manure whence it grew. 

CHLORINE. 

Source. — In the free state this element is a gas. Its chief 
source is common salt, more than half of which is chlorine. 

Preparation. — About a quarter of an ounce of salt and the 
same amount of black manganese oxide are mixed, and placed 
in a test-tube with sufficient water to cover them ; on adding a 



28 



NON-METALLIC ELEMENTS. 



small quantity of sulphuric acid the evolution of chlorine gas 
commences. For the mode of collection see the following 
paragraphs. 

Another Process. — As the action of the sulphuric acid on the 
salt in the above process is mainly to give hydrochloric acid, 
the latter acid (about 4 parts) and the black manganese oxide 
(about 1 part) may be used in making the gas, instead of salt, 
sulphuric acid, and black manganese oxide. This, the usual 
process, is that adopted in the British and United States Phar- 
macopoeias. 

Collection and Properties. — Free chlorine is a suffocating gas. 
Care therefore must be observed in experimenting with this 
element. As soon as its penetrating odor indicates that it is 
escaping from the test-tube, the cork and delivery -tube (similar 
to that used in making oxygen) should be fitted on, and the gas 
passed to the bottom of another test-tube containing water 
(Fig. 10). When thirty or forty small bubbles have passed, 
their evolution being assisted by slightly heating the generating 
tube, the latter should be removed to the cupboard usually pro- 
vided in laboratories for performing operations with noxious 
gases, or be dismounted and the contents carefully and rapidly 



Fig. 10. 



Fig. 11. 





Preparation of Chlorine. 

washed away. The water in the collecting-tube will now be 
found to smell of the gas, chlorine being, in fact, soluble in 
about half its bulk of water. Chlorine-water is official* in 



* " The Pharmacopoeia and all in it is official {office, Fr. from L. officium, 
an office). There are many things which in Pharmacy are officinal (Fr. 
from L. officina, a shop), bnt not official. To restrict the word officinal 
to the contents of a pharmacist's shop, and to that portion of the contents 
which is pharmacopceial, is radically wrong, and should be avoided."— 
J. A., second edition, 1869. 



CHLORINE. 29 

the British and United States Pharmacopoeias (Aqua Chlori, 
U. S. P.). 

Larger quantities may be made from the hydrochloric acid and 
black manganese oxide (4 to 1 ) in a Florence flask fitted with a 
delivery-tube, the flask being supported over a flame by the ring of 
a retort-stand or any similar mechanical contrivance (Fig. 11). A 
piece of cardboard on the neck of the collecting-bottle, as indicated 
in the figure, retards diffusion of the chlorine gas from the bottle 
during the process of collection. 

Mem. — Flasks and similar glass vessels are less liable to fracture 
if protected from the direct action of the flame by being placed on a 
piece of wire gauze two to four inches square, or on a sand-bath ; 
that is, a saucer-shaped tray of sheet iron on which a thin layer of 
sand is placed. 

The Vapor Chlori, B. P., or inhalation of chlorine, is simply 
moist chlorinated lime so placed that some of the chlorine given off 
may be inhaled. 

During these manipulations the operator will have noticed that 
chlorine is of a light yellowish-green color. The tint is observable 
when the gas is collected in large vessels. As it is soluble in water 
(2£ vols, in 1 vol. at 60° F.), it cannot be economically stored over 
that liquid. Being, however, nearly twice and a half as heavy as 
air, the gas may be collected by simply allowing the delivery-tube 
to pass to the bottom of a dry test-tube or dry bottle (Fig. 11). 

A distinctive property of free chlorine is its bleaching power. 
Prepare some colored liquid by placing a few chips of logwood 
or other dyeing material in a test-tube half full of hot water. 
Pour off some of this red infusion into another tube and add a 
few drops of the chlorine-water; the red color is rapidly 
destroyed. 

Free chlorine readily decomposes offensive effluvia ; it is one of 
the most powerful of deodorizers. It also decomposes putrid and 
infectious matter ; it is one of the best of disinfectants. [Antiseptics 
are substances which prevent putrefaction. See Index.) 

"An official formula is one given under authority. An officinal formula 
is one made in obedience to the customary usage of the shop (officina). 
To state that any preparation under the sanction of the British Pharma- 
copoeia is officinal is a misapprehension of the meaning of the word." — 
J. JBrough. 

"That is official which emanates from a recognized authority. That is 
officinal which is issued from an officma or workshop." — J. Inch. 

"Official writings and orders are those issued by official persons. 
Officinal articles arc such as are found in a shop."— J. F.StANFOED, M.A., 
F. B.S. 

"It will be observed that the word 'official' has been used in this 
edition of the Pharmacopoeia in place of the word ' officinal.' This change 
was made by a special vote of the committee at one of its first meetings 
in 1890." — United States Pharmacopoeia. 



30 NON-METALLIC ELEMENTS. 

Combination of Hydrogen with Chlorine, forming Hydrochloric 
Acid. — If an opportunity occurs of generating chlorine in a 
closed chamber or in the open air, a test-tube, of the same size 
as one of those in which hydrogen has been retained from a 
previous operation, is filled with the gas. The hydrogen tube 
is then inverted over that containing the chlorine, the mouths 
being kept together by encircling them with a finger. After 
the gases have mixed, the mouths of the tubes are quickly in 
succession brought near a flame, when explosion occurs, and 
fumes of a compound of hydrochloric acid gas with the moist- 
ure of the air are formed. The hydrochloric acid of pharmacy 
(Acidum Hydrochloriciim, U. S. P.) is a solution of the gas 
(made in a more economical way) in water. 

The foregoing experiment affords evidence of the powerful affinity 
of chlorine and hydrogen for each other. Chlorine dissolved in 
water will, in sunlight, slowly remove hydrogen from some of the 
water and liberate oxygen. The bleaching power of chlorine is . 
generally referred to this indirect oxidizing effect which it produces 
in presence of water, for dry chlorine does not bleach. 

Density. — Chlorine gas is thirty-five and a half times as 
heavy as hydrogen gas. A wine-bottle would hold about 35 J 
grains. 

SULPHUR, CARBON, IODINE. 

The physical properties (color, hardness, weight, etc.) pos- 
sessed by these elements when they are in the free state are 
familiar. Their leading chemical characters in the free state 
will also be understood when a few facts concerning each are 
made the subject of experiment. 

Sulphur. — Burn a small piece of sulphur ; a penetrating 
odor is produced, due to the formation of a colorless gas. The 
product is a perfectly definite chemical compound of the oxy- 
gen from the air with the sulphur. It is termed sulphurous 
anhydride or sulphurous acid gas. 

Carbon is familiar, in the free form, as soot, coke, charcoal, 
graphite (or plumbago, popularly termed black lead), and 
diamond. The presence of combined carbon in wood and in 
other vegetable and animal matter is at once rendered evident 
by heat. Place a little tartaric acid on the end of a knife in a 
flame ; the blackening that occurs is due to the separation of 
carbon. The black matter at the extremity of a piece of half- 
burned wood is also free carbon. 

Carbon, like hydrogen, phosphorus, and sulphur, has a great 
affinity for oxygen at high temperatures. A striking evidence of 



THE ELEMENTS, THEIR SYMBOLS, ETC. 31 

that affinity is the evolution of sufficient heat to make the materials 
concerned red or even white hot. When ignited in the diluted 
oxygen of the air, carbon simply burns with a moderate glow, as 
seen in an ordinary coke or charcoal fire ; but when ignited in pure 
oxygen, the intensity of its combination is greatly exalted. The 
product of the combination of the two elements, if the oxygen be in 
excess, is an invisible gaseous body termed carbonic acid gas ; if 
the carbon be in excess, another invisible gas, termed carbonic 
oxide, results. 

Iodine. — A prominent chemical characteristic of free iodine 
is its great affinity for metals. Place a piece of iodine about 
the size of a pea in a test-tube with a small quantity of water, 
and add a few iron filings or small nails. On gently warming 
this mechanical mixture, or even shaking if longer time be 
allowed, the color and odor of the iodine disappear ; it has 
chemically combined with the iron — a chemical <-<>iii)><>uu<l lias 
been produced. If the fluid be filtered, a clear aqueous solu- 
tion of the compound of the two elements is obtained. 

The solution, made as above and mixed with sugar, forms, when 
of a certain strength, the ordinary syrup of iodide of iron of phar- 
macy (Syrupus Ferri Iodidi, U. S. P., or syrup of ferrous iodide). 
A strong solution mixed with sugar and liquorice-root constitutes 
the corresponding pills (Pilulce Ferri Iodidi, U. S. P., or pills of 
ferrous iodide). The solid iodide is obtained on removing the 
water of the above solution by evaporation. 

Sulphur and Iron, also, when very strongly heated, chemically 
combine to form a substance which has none of the properties of a 
mixture of sulphur and iron ; that is, has none of the characters of 
sulphur and none of iron, but new properties altogether. The prod- 
uct is termed Ferrous Sulphide, V . S. P., or sulphide of iron. Its 
manufacture and uses will be alluded to in treating of the com- 
pounds of iron ; it is mentioned here as a simple but striking illus- 
tration of the difference between a chemical compound and a mechani- 
cal mixture. 

THE ELEIYIENTS, THEIR SYMBOLS, Etc. 

From the foregoing statements a general idea will have been 
obtained of the nature of several .of the more frequently occurring 
free elements. Some additional facts concerning them may be 
gathered from the following table, which gives the name in full, 
the symbol (or shorthand character*) of the name, and the origin 
of the name. 

For the purposes of study by medical and pharmaceutical pupils 
the elements may be divided into three classes — viz. those fre- 
quently, those seldom, and those never used in pharmacy. 

* The symbol is also much more than the shorthand character, as will 
presently be apparent. 



32 



THE ELEMENTS, THEIR SYMBOLS, ETC. 



Name. 



Oxygen 



Hydrogen 



Nitrogen 

Carbon 
Chlorine 



Iodine . . . 
Sulphur . . 

Phosphorus 



Potassium 
(Kalium) 



Sodium . . 
(Natrium) 



Ammonium 



Barium 



Calcium . 
Magnesium 



Symbol. 



N 



Iron . . . . 
(Ferrum) 



K 



Na 



NH 4 



Ca 
Mg 



Fe 



Derivation of Name. 



From 6£u S (oxus), acid, and yeeeo-i? (genesis), 
generation, i. e. generator of acids. When 
first discovered it was supposed to enter into 
the composition of all acids. 

From vSojp (hudor), water, and yeVe<ns (gene- 
sis), generation, in allusion to the product of 
its combustion in air. 

From virpov (nitron), and yeVeo-i? (genesis), 
generator of nitre. 

From carbo, coal, which is chiefly carbon. 

From x^pos (chloros), green, the color of 
this element. 

From lov (ion), a violet, and elSo? (eidos), 
likeness, in reference to the color of its vapor. 

From sal, a salt, and nvp (pur),^re, indicat- 
ing its combustible qualities. Its common 
name, brimstone, has the same meaning, being 
the slightly altered Saxon word, brynstone, 
i. e. burn stone. 

<*>ws (ph5s), light, and <J>epeu> (pherein), to 
bear. The light it emits may be seen on 
exposing it in a dark room. 

Kalium, from kali, Arabic for ashes (see 
next paragraph). Manufactories in which 
compounds of potassium and allied sodium- 
salts are made are called alkali-works to this 
day. Potassium, from pot-ash, so called be- 
cause obtained by evaporating the lixivium 
of wood-ashes in pots. 

Natrium, from natron, the old name for 
certain natural deposits of carbonate of 
sodium. Sodium, from soda-ash or sodash, the 
residue of the combustion of masses or sods 
of marine plants. Sod-ashes were chemically 
distinguished from pot-ashes by Duhamel 
in 1736. Previously both were simply kali 
or ashes from two different sources. Sir 
Humphry Davy first isolated the two metals 
in 1807. 

This body is not an element, but its com- 
ponents exist in all ammoniacal salts, and 
apparently play the part of such elements 
as potassium and sodium. Sal ammoniac 
(chloride of ammonium) was first obtained 
from near the temple of Jupiter Ammon in 
Libya ; hence the name. 

From /3apu? (barus), heavy, in allusion to 
the high specific gravity of "heavy spar," 
the most common of tbe barium minerals. 

Calx, lime, the oxide of calcium. 

From Magnesia, the name of the town (in 
Asia Minor) near which the substance now 
called " native carbonate of magnesium " 
was first discovered. 

Prehistoric. The spelling may be from 
the Saxon iren, the pronunciation from the 



THE ELEMENTS, THEIR SYMBOLS, ETC. 



33 



Name. 



Symbol. 



Derivation of Name. 



Aluminium . 



Zinc 



Arsenium, 
Arsenicum, }► 
or Arsenic 



Antimony . 
(Stibiuin) 



Copper . . . 

(Cuprum) 



Lead . . . . 
(Plumbum) 



Mercury .... 
(Hydrargyrum) 



Silver . . . . 

(Argentum) 



Al 
Zn 

As 

Sb 

Cu 
Pb 
Hg 

Ag 



Gotbic " iam." Tbe derivation is perhaps 
Aryan ; it probably originally meant metal. 

The metallic basis of alum was at first 
confounded with that of sulphate of iron, 
which was the alum of the Romans, and was 
so called in allusion to its tonic properties, 
from alo to nourish. 

From Ger. Zinn, tin, with which zinc 
seems at first to have been confounded. 

'ApaevtKov (arsenikon), the Greek name for 
orpiment, a sulphide of arsenium. Common 
white "arsenic" is an oxide of arsenium. 
Arsenium as the name of the element, and 
arsenic as the old and widely recognized 
name of the common white oxide, are the dis- 
tinctive names which science and expediency 
alike suggest. 

2n'/3i (stibi), or <rn>/Ai (stimuli), was the 
Greek name for the native sulphide of anti- 
mony. The word antimony is said to be 
derived from 6u>tI (anti), against, and moine, 
French for monk, from the fact that certain 
monks were poisoned by it. 

From Cyprus, the name of the Mediter- 
ranean islaud where this metal was first 
worked. 

The Latin word is expressive of " some- 
thing heavy," and the Saxon Ised has a 
similar signification. 

Hydrargyrum, from v5<op (huddr), water, 
and apyvpos (arguros), silver, in allusion to its 
liquid and lustrous characters. Mercury, 
after the messenger of the gods, on account 
of its susceptibility of motion. The old 
name quicksilver also indicates its ready 
mobility and argentine appearance. 

'Apyvpos (arguros), silver, from ipybs (argos), 
white. Words resembling the term silver 
occur in several languages, and indicate a 
white appearance. 



The following are names of some of the less frequently 
occurring elements, compounds of which, however, are alluded 
to in the British and United States Pharmacopoeias or are met 
with in pharmacy : 



Name. 



Bromine . . 
Fluorine . . 



Symbol. 



Br 
Fl 



Derivation of Name. 



From jSpi/oto? (bromos), a stink. It has an 
intolerable odor. 

From fluo, to flow. Fluoride of calcium, 
its source, is commonly used as a flux in 
metallurgic operations. 



34 



Name. 



Boron . . 

Silicon . . 
Lithium . 

Strontium 



Cerium 



Chromium 
Manganese 



Cobalt 



Nickel 



Tin (Stannum) 

Gold (Aurum) 

Platinum . . 
Bismuth . . . 

Cadmium. . . 



Si 
L 

Sr 

Ce 

Cr 
Mn 

Co 



Sn 

Au 

Pt 
Bi 

Cd 



Derivation of Name. 



From borak or baurak, the Arabic name of 
borax, the substance from which the element 
was first obtained. 

From silex, Latin for flint, which is nearly 
all silica (an oxide of silicon). 

From Attfeios (litheios), stony, in allusion to 
its supposed existence in the mineral king- 
dom only. 

This name is commemorative of Strontian, 
a mining village in Argyleshire, Scotland, 
in the neighborhood of which the mineral 
known as strontianite, or carbonate of stron- 
tium, was first found. 

Discovered in 1803, and named after the 
planet Ceres, which was discovered on Jan. 1, 
1801. The oxalate of cerium is official, but 
seldom used. 

From xP^i JLa (chroma), color, in allusion to 
the characteristic appearance of its salts. 

Probably the slightly altered word mag- 
nesia, with whose compounds those of man- 
ganese were confounded till 1740. 

Cobalus, or Kobold, was the name of a demon 
supposed to inhabit the mines of Germany. 
The ores of cobalt were formerly troublesome 
to the German miners, and hence received 
the name their metallic radical now bears. 

Nickel, from nil, worthless. Nickel ore was 
formerly called Kupfernickel, false copper. 
When a new element was found in the ore, 
the name nickel was retained for it. 

Both words are possibly corruptions of the 
old British word staen, or the Saxon word 
stan, a stone. Tin was first discovered in 
Cornwall, and the ore (an oxide) is called 
tinstone to the present day. 

Aurum (Latin), from a Hebrew word sig- 
nifying the color of fire. 

Gold, a similar word is expressive of bright 
yellow in several old languages. 

From platina (Spanish), diminutive of 
plata, silver. It somewhat resembles silver, 
but is less white and lustrous. 

Slightly altered from the German Wis- 
muth, derived from Wiesematte, "a beautiful 
meadow," a name given to it originally 
by the old miners in allusion to the prettily 
variegated tints presented by the freshly 
exposed surface of the crystalline metal. 

KaSixeia (Kadmeia) was the ancient name 
of calamine (carbonate of zinc), with which 
carbonate of cadmium was long confounded, 
the two often occurring together. 



THE ELEMENTS, THEIR SYMBOLS, ETC. 35 

Gold, Platinum, Tin and Silicon are classed with the less im- 
portant elements, because their salts are seldom used in pharmacy. 

It will be noticed that the symbol of an element is simply the 
first letter of its Latin name, which is generally the same as in 
English. Where two names begin with the same letter, the less 
important has an additional letter added. 



QUESTIONS AND EXEECISES. 



Of how many elements is terrestrial matter composed ? — Iu what state 
do the elements occur in nature ? — Distinguish between the art and the 
science of chemistry. — What is the difference between an element and a 
compound? — Enumerate the chief non-metallic elements. — Describe a 
process for the preparation of oxygen. — How are gases usually stored ? 
— Mention the chief properties of oxygen. — What is the source of animal 
warmth ?— State the proportion of oxygen in air.— Is the proportion 
constant, and why ?— Give a method for the elimination of hydrogen from 
water.— State the properties of hydrogen. — Why is a mixture of hydrogen 
and air explosive?— Explain the effects producible by the ignition of 
large quantities of coal-gas and air. — What is the nature of combustion? — 
Define a combustible and a supporter of combustion. — Describe the struc- 
ture of flame.— State the principle of the Davy safety-lamp.— To what 
extent is hydrogen lighter than oxygen ?— What do you mean by diffusion 
of gases?—* State : Graham's law concerning diffusion.— Name the source 
of phosphorus, and give its characters. — Why does phosphorus burn in 
air? — What remains when ignited phosphorus has removed all the oxy- 
gen from a confined portion of air ?— Mention the properties of nitrogen. — 
What office is fulfilled by the nitrogen of the air? — State the proportions 
of the chief constituents of air. — Mention the minor or occasional con- 
stituents of air. — What is the proportion by weight of nitrogen to oxygen 
in the atmosphere? — Give the specific gravity of nitrogen. — How is 
chlorine prepared? — Enumerate the properties of chlorine. — Define the 
terms deodorizer and disinfectant. — Explain the bleaching effect of 
chlorine. — -What proportion of hydrogen to chlorine is necessary for the 
formation of hydrochloric acid gas?— State the prominent chemical and 
physical characters of sulphur. — State those of carbon. — State those of 
iodine. — Give the derivations of the names of some of the elements. — 
What are the symbols of oxygen, hydrogen, nitrogen, carbon, chlorine, 
iodine, sulphur, phosphorus? 



The Learner is recommended to read the following para- 
graphs on the General Principles of Chemical Philosophy 
carefully once or twice, then to study (experimentally, if 
possible) the succeeding pages, returning to and reading over 
the General Principles from time to time until they are 
thoroughly comprehended. 

THE GENERAL PRINCIPLES OF CHEMICAL 
PHILOSOPHY. 



Definition of Chemical Action. 

The learner may now proceed to study the manner in which sub- 
stances act chemically on each other. By acting chemically it will 



36 GENERAL PRINCIPLES OF 

be obvious, from the preceding experiments, that what is meant is 
so affecting each other that the substances are greatly altered in 
properties. A mixture of free oxygen gas and hydrogen gas is still 
a gas ; a chemical compound of oxygen and hydrogen is a liquid — 
namely, water ; here is great alteration in properties. Iodine is 
only slightly soluble in water, and forms a brown-colored solution, 
and iron is insoluble 5 but when iodine and iron are chemically com- 
bined, the product is very soluble in water, forming a light-green 
solution in which the eye can detect neither iodine nor iron, and 
Which is utterly unlike iron or iodine in any one of their properties. 
Sand, sugar, and butter, rubbed together, form a mere mixture, 
from which water would extract the sugar, and ether dissolve out 
the butter, leaving the sand. Tartaric acid, sodium carbonate, and 
water, mixed together, form a chemical compound containing neither 
an acid nor a carbonate, these bodies having interacted and formed 
fresh combinations. These illustrations show that chemical action 
is distinguished from all other actions by (a) producing an entire 
change of properties in bodies. It also is (b) exerted only between 
definite weights and volumes of matter. This (a and b) cannot be 
said of any other action — the action of any of the other great forces 
of nature (gravitation, heat, light, electricity, etc.) ; hence the state- 
ments (a and b) furnish a sharp and precise definition of chemical 
action or the chemical force. Further, (c) chemical action is only 
exerted when the substances are close together. 

Atoms. 

In a chemical compound what has become of its constituents? 
Let the reader place before him specimens of sulphur, iron, and 
iron sulphide (Ferrous Sulphide, U. S. P.), or iodine, iron, solid 
iron iodide, and its solution in water or syrup (Syrupus Ferri Iodidi, 
U. S. P.). In the ferrous sulphide what has become of the sulphur 
and of the iron from which it was made ? The mixture of sulphur 
and iron in combining to form ferrous sulphide has not lost weight, 
and, indeed, by certain processes it is possible to recover its sulphur 
as sulphur and its iron as iron 5 so that we are compelled to believe 
(we cannot avoid the conclusion) that ferrous sulphide contains 
particles of sulphur and of iron. But how small must be these 
particles ! Rub a minute fragment to dust in a mortar and place a 
trace of the powder under the highest power of the best micro- 
scope; no yellow particle is visible, not the minutest portions of 
lustrous metal, but dull-brown miniature fragments of the original 
mass. The ultimate particles of sulphur and iron, or of the elements 
in any other compound (the chlorine and sodium in common salt or 
the iodine and iron in solution of ferrous iodide), are, in short, too 
small to be seen. Can they be imagined ? Again, no ! The mind 
cannot conceive of an ultimate particle (sulphur, iron, ferrous sul- 
phide, or what not) so small but what the next instant the imagina- 
tion has divided it. Yet learner and teacher must have some 
common platform on which to reason and converse. The difficulty 
is met by speaking of these inconceivably small particles as atoms 



CHEl^CAL PHILOSOPHY. 37 

(aro/Lioc, atomos, indivisible, from the privative a and te/hvo), temno, to 
cut — that which is not cut or divided), an idea first thoroughly 
worked out by an Englishman, Dalton, at the commencement of the 
present century. 

The Greeks had a vague notion that matter could not be infinitely 
divisible ; that there must be some limit to the divisibility of 
matter ; that all matter must be made up of ultimate particles. 
Democritus, 400 b. c, held that matter was formed of atoms. But 
it was Dalton who, chiefly through employing the balance, gave 
exactitude to this notion, and by his broad mental grasp converted 
a vague hypothesis into a sound and satisfactory theory that all the 
world has since accepted and employed in explanation of the facts 
relating to those changes or alterations in matter which had up to 
his time proved so inexplicable. Doubtless the theory is only a 
theory. We may never be able to demonstrate the existence of 
atoms. But it is a theory supported by all known facts — one of 
those short reflections of facts dear to healthily constituted minds ; 
moreover, it is the only theory possible to the majority of minds in 
the present state of knowledge and education. 

We cannot speak of iodine and iron uniting lump to lump, as two 
bricks are cemented together or blocks of wood glued together, for 
such is not the kind of action. We cannot select minute fragments 
of each to regard as the combining portions ; for the minutest frag- 
ment we could obtain is visible, and ferrous iodide contains neither 
visible iodine nor visible iron. And yet ferrous iodide contains both 
iodine and iron, or, at least, a given weight of the compound is 
obtained from the same weight of constituents, and the same weight 
of constituents is obtainable from an equal weight of the compound. 
We might say that molecules are concerned in the operation ; but a 
molecule means a little mass of — of what? There is positively no 
word left with which to carry on conversation and description but 
atoms. Any other mode of treating the matter is too subjective for 
general employment. Moreover, any difficulty in forming a definite 
conception of an atom is met by regarding an atom not necessarily 
as something which cannot be divided, but as " a particle of matter 
which undergoes no further division in chemical metamorphoses" 
(Kekule). Even physicists regard atoms from much the same point 
of view ; indeed, they often speak of still larger portions of matter 
(molecules) as atoms, meaning thereby " something which is not 
divided in certain cases that ive are considering" [Clifford). Dal- 
ton' s Atomic Theory will again be referred to within the next 
twenty pages, more especially as explanatory of the curious fixed- 
ness of the weights and volumes in which elements and compounds 
alone combine with each other. 



. The Chemical Force. 

What power binds the atoms of a chemical compound together in 
such marvellous closeness of union that in the couple or group they 
lose all individuality? Clearly an attractive force of enormous 
power — a force remotely resembling, perhaps, that which attracts 



38 GENEEAL PEINCIPfcES OF 

a piece of iron to a magnet. Only by such an assumption can we 
conceive that common salt contains chlorine and a metal (sodium), 
or that wood contains carbon, hydrogen, and oxygen. Were not 
this force thus all-powerful, the carbon in wood would show its 
blackness and other qualities, and the hydrogen and oxygen give 
indications of their gaseous and other characters. This attractive 
force is commonly termed the chemical force, sometimes chemical 
affinity. The word chemism has also been proposed for it, just as 
the magnetic force is termed magnetism, but the word has not 
generally been adopted. 

Whence comes the chemical force? Whence comes matter? We 
can neither create nor destroy matter ; we can neither create nor 
destroy force. We can alter matter from one form to another ; we 
can alter force from one form to another. The various forms of 
compounds are thus co-related 5 the various forces are co-related. 
But of the whence and whither, either of matter or of force, we 
know nothing. 

Molecules. 

A free, uncombined atom probably cannot exist in a state of 
isolation at common temperatures for any appreciable length of 
time. For we must regard an atom as the home of an attractive 
force of great intensity, and the moment such an atom is liberated 
from a state of combination (say, hydrogen from water or chlorine 
from salt), it finds itself in proximity to another atom having 
similar desires for union, so to speak ; the result is an impetuous 
rushing together and formation of either couples, trios, or groups 
according to the nature of the atoms. It would be as difficult to 
conceive of separate atoms as to imagine that a strong magnet and a 
piece of steel could be suspended close to each other without being 
drawn together. It is doubtless possible to keep some pairs of 
atoms apart by the aid of heat, just as the magnet and steel may be 
parted by a superior amount of force 5 but such a condition of things 
is abnormal. These pairs and other groups of atoms are con- 
veniently designated by the one word molecule, the diminutive of 
mole^ a mass — literally, little masses. Dissimilar kinds of atoms 
seem to have greater attraction for each other than similar kinds ; 
for, first, the masses of matter met with in nature in the great 
majority of cases contain two or more dissimilar elements ; and, 
secondly, at the moment certain elements are liberated from their 
combinations they are very specially active in combining with other, 
different, elements ; that is to say, the chances are not equal that the 
liberated elements will either retain their elementary condition or 
combine to form compounds, but the cases in which compounds are 
formed are actually in great majority. 

The study of the chemistry of molecules, qua molecules, is of 
great interest ; but the study of the chemistry of the atoms or groups 
of atoms within molecules is of enormously greater interest. A 
molecule of nitrogen, for instance, is not very active ; an atom of 
nitrogen has activity which even the most advanced chemist finds 
difficult of realization. 



CHEMICAL PHILOSOPHY. 39 

Recapitulation. 
It is desirable that the learner should here make some experiment 
which will serve to bring again under notice in an applied or con- 
crete form what has just been stated respecting the substances 
termed chemical compounds, and concerning the character of that 
chemical force which resides in the atoms of molecules. The follow- 
ing will usefully serve this purpose ; it is the process for detecting a 
trace of sulphurous acid in common liquid hydrochloric acid : 

As already proved, hydrogen gas and chlorine gas, when 
interunited in a manner presently explained, form hydrochloric 
acid gas : the latter dissolved in water is the ordinary colorless 
liquid of the shops termed hydrochloric acid, the Acidum Hydro- 
chloricum of pharmacopoeias. Common yellow acid not infre- 
quently contains as an impurity a trace of sulphurous acid 
gas, a body also already mentioned and experimentally pre- 
pared — a trace too small to be detected by its odor. Obtain a 
specimen of common liquid hydrochloric acid containing as 
an impurity a trace of sulphurous acid, or adopt the more 
simple course of purposely adding a few drops of aque- 
ous solution of sulphurous acid (Acidum Sulphur osum* U. S. 
P.) to some hydrochloric acid. (If no sulphurous acid is at 
hand, the object may be accomplished by putting a quarter or 
half an ounce of liquid hydrochloric acid into a wide-mouthed 
bottle, then burning a fragment of sulphur on a wire or strip 
of wood inside the bottle for a few seconds, and shaking the 
gas and liquid together.) Pour some of the impure liquid 
hydrochloric acid into a test-tube, add about an equal bulk of 
water, and then drop in a few fragments of the metal zinc. 
Eifervescence will occur, due to the escape of inodorous hydro- 
gen gas, together with a small quantity of a badly-smelling 
gas termed sulphuretted hydrogen (Hydrogen Sulphide or 
Hydromlphuric Acid, U. S. P.). Bring the mouth of the tube 
near the nose ; the presence of sulphuretted hydrogen will at 
once be recognized. 

The hydrochloric acid has now been tested for sulphurous acid. 
If the experiment be performed on any commercial specimen of the 
acid, and a smell of sulphuretted hydrogen be observed, the operator 
will at once be able to state that the specimen contains sulphurous 
acid as an impurity. 

Now, using Dalton's theory of the atomic constitution of matter, 
the explanation of what occurs in the successive steps of the fore- 
going experiment is as follows : 

Hydrochloric acid is a chemical compound of hydrogen and chlo- 
rine. That it is a chemical compound, and not a mere mechanical 

* These aqueous solutions of acids are generally, for the sake of brev- 
ity, simply termed acids. 



40 GENERAL PRINCIPLES OF 

mixture of hydrogen and chlorine, is shown by the fact that its 
properties are altogether different from the properties of its constit- 
uents. The attractive power or chemical force resident in the atoms 
of the molecules of chlorine and of hydrogen has caused the atoms 
to combine in the closest manner imaginable, and form pairs of 
atoms or molecules of the chemical compound — hydrochloric acid. 
Zinc being introduced into the acid, and the atoms of zinc and chlorine 
having even still greater attraction for each other than the hydrogen 
for the chlorine, the zinc and chlorine atoms combine and form a 
new molecule (termed zinc chloride), which remains in the liquid, 
while the hydrogen atoms, having the atoms of no other element "to 
combine with if the acid is pure, unite to form pairs, or molecules, 
of hydrogen, and in that state escape from the vessel. If the acid 
be impure from the presence of sulphurous acid (sulphurous acid 
gas, it will be remembered, is a compound of sulphur and oxygen), 
some of the hydrogen atoms at the moment of birth, their nascent 
state (from nascor, to be born)— the specially active state — finding the 
atoms of other elements present — namely, the atoms of sulphur and 
oxygen of the sulphurous acid molecules — combine by preference 
with these atoms and form new molecules, the sulphur and hydrogen 
forming sulphuretted hydrogen, and the oxygen and hydrogen pro- 
ducing water ; the former escapes with the great bulk of the hydro- 
gen, while the water remains with the water already in the vessel. 

Note. — Ordinary hydrogen gas — that is, hydrogen in the molec- 
ular, not in the atomic or nascent condition — will not thus attack 
sulphurous acid. Doubtless the amount or extent of attraction of 
two atoms of hydrogen for one atom of, say, the sulphur in the sul- 
phurous acid molecule, is a constant amount ; but the uncombined, 
nascent atoms can, it is only fair to suppose, get much nearer to the 
attacked molecule than they can after they have themselves com- 
bined to form a molecule, molecules (but scarcely atoms) having an 
appreciable amount of space between them, as will be further shown 
almost immediately. In other words, it is probably distance which 
prevents an attack which would be inevitable at close quarters. 
These remarks apply to all similar reactions of other elements. The 
great activity of nitrogen in what the student will now see is its 
atomic rather than merely nascent condition, as compared with its 
slight activity in what now may be termed its molecular condition, 
has already been alluded to (page 27). 

Conditions and Nature of the Manifestation of the Chemical 

Force. 
The exertion of chemical affinity is only possible when the masses 
of the bodies touch. Thus it was necessary to bring the oxygen, 
hydrogen, phosphorus, chlorine, sulphur, carbon, iodine, and iron 
into ordinary contact in the respective experiments with those ele- 
ments before the various reactions occurred. The exact nature of 
these actions, as indeed of all in which substances act chemically, 
would seem to be an interchange, most generally a mutual one, of 
the atoms of which the molecules consist — a change of partners, so 
to speak. Thus, in the experiment in which hydrogen and chlorine 



CHEMICAL PHILOSOPHY. 41 

gases united to form hydrochloric acid gas, a pair of atoms in a 
hydrogen molecule and a pair of atoms in a chlorine molecule, find- 
ing themselves opposite to each other, changed places, the atoms of 
each of the old molecules unlinking, so to say, and pairing off in 
fresh couples : 

f Hydrogen ) d f CWorine j fe f Hydrogen } d f Hydrogen { 

( Hydrogen J [ Chlorine J ( Chlorine J { Chlorine J 

Or, using the symbols of these elements instead of the full names, 
H H and CI CI become H CI and H CI. Still further economizing 
space and trouble, the statement may be made in the following 
form : H 2 and Cl 2 become 2HC1. Once more, by using the pliis 
sign (+), instead of the words " and" or " added to," and the sign 
or symbol — or equal, instead of the words "become" or "are 
equal to," we reach the shortest expression : H 2 -\- Cl 2 = 2HC1 ; and 
this is the form in which it may be expressed in the student's note- 
book. It is the shortest and most convenient form, and is instruct- 
ive and suggestive to the mind. 

Chemical Notation. 

We have thus gradually arrived at a spot in the path of chemical 
philosophy at which we must halt to more fully discuss the usual 
method of recording chemical travels. We have arrived at the sub- 
ject of chemical notation (from noto, to mark), the art or practice of 
recording chemical facts by short marks, letters, numbers, or other 
signs. Already the first capital letter, or the first and one of the 
following small letters, of the Latin names of the elements have 
been employed as contractions, or shorthand expressions, or symbols 
of the whole name. Thus H has been used for the word "hydro- 
gen," and CI for " chlorine." A second function of such a symbol 
is that of indicating one atom. Thus H stands not only for the 
word or substance " hydrogen," but for one atom of hydrogen. 
Large and small figures (2 or 2 ) indicate a corresponding number of 
atoms, the small figure only multiplying the one particular symbol 
to which it is attached, while a large figure multiplies all the sym- 
bols it precedes. Thus H 2 means two atoms of hydrogen, and Cl 2 
two atoms of chlorine, while 2HC1 means two atoms of hydrogen 
and two atoms of chlorine, or, in one word, two molecules of hydro- 
chloric acid gas. A third function of such a symbol as H or CI is 
that of indicating one volume of the element in the gaseous state. 
Thus H, CI, or stand, first, for the substances named hydrogen, 
chlorine, and oxygen ; secondly, for single atoms of hydrogen, chlo- 
rine, and oxygen ; thirdly, they represent single and equal volumes 
of chlorine, hydrogen, and oxygen. It will be remembered that one 
test-tubeful of hydrogen and an equal-sized test-tubeful of chlorine 
were embloyed in a previous experiment in forming hydrochloric 
acid gas, HC1. 

The position of symbols counts for something. Thus, HC1 indi- 
cates not only the substances hydrogen and chlorine, single atoms 
of each of the substances, and equal volumes of each, but also 
that the two substances are joined together by the chemical force, 
4* 



42 GENERAL PRINCIPLES OF 

If the two letters were placed one under the other or at some 
distance apart, or were separated by a comma or a plus sign (+), 
they would be understood to mean a mere mixture of the elements ; 
but placed as close as the printer's type will conveniently and con- 
sistently allow, they must be considered to stand for a compound of 
the elements ; that is to say, hydrochloric acid gas (HC1). The col- 
lection of symbols representing a molecule is termed a formula. 
II 2 , Cl 2 , and HC1 are the formulae, of hydrogen, chlorine, and hydro- 
chloric acid gas. 

H 2 + C1 2 = 2HC1. 

Such a set of letters, figures, and marks as that on the above line 
is collectively termed an equation, because it indicates the equality 
of the number and nature of the atoms before and after chemical 
action. On the left hand of the sign of equality ( — ) are shown two 
molecules, and on the right hand two molecules ; but of the mole- 
cules on the left, one contains two atoms of hydrogen and the other 
two atoms of chlorine, while of the molecules on the right each con- 
tains one atom of hydrogen and one of chlorine. The equation forms 
a short and convenient plan of recording the facts of experiment. 

Instead of an equation, a diagram may be employed to exhibit the 
same facts. Thus : 

HC1 



HC1 



PHYSICAL AND CHEMICAL CONSTITUTION OF MATTER.. 

Relations of Gases, Liquids, and Solids. 

Molecules of gases are not in absolute contact, for a volume of 
gas may be compressed with very little force to half or one-fourth 
its bulk — in short, to such an extent that in many cases the mole- 
cules sufficiently approximate to form a liquid. In a liquid the 
molecules are still free to glide about with, ease amongst each other ; 
and though in solids they exhibit less mobility, still even solids may 
be compressed by powerful pressure, so that probably in no instance 
are molecules in absolute contact. (Moreover, from the researches 
of Caignard de la Tour and of Andrews there would seem to be no 
sharp lines of demarcation between the gaseous, liquid, and solid 
conditions of substances.) One's mental picture of the relative 
position of the molecules of gaseous, vaporous, liquid, or solid 
matter must be such a picture as that of the moving particles of 
dust in the air of a room, or such a relation to each other as that of 
the planets and stars suspended in space. There is abundant experi- 
mental evidence to warrant such a conception. A clear, transparent 
fluid appears perfectly homogeneous, but is not so. Its particles are 




CHEMICAL PHILOSOPHY. 



43 



not in contact. Every person who has mixed 5 pints of rectified 
spirit with 3 pints of water knows that the 100 fluidounces of spirit 
and 60 fluidounces of water do not when mixed give 160 ounces of 
"proof" spirit, but only 156 ounces ; the molecules of the liquids 
have gone closer together, having probably a little attraction for each 
other. Having gone closer together, they were not previously so 
close together, the necessary conclusion being that even liquids are 
porous. Why a gas under pressure should immediately return to 
its original bulk when the pressure is removed, while a liquefied or 
solidified gas only slowly resumes the gaseous or vaporous state, is a 
question which requires for discussion a knowledge of the nature of 
forces other than the chemical. For it must be remembered that the 
study of the chemical force is mainly the study of the internal con- 
stitution of molecules ; the study of the properties of entire mole- 
cules forming the domain of Physics, sometimes termed Natural 
Philosophy. (Physics, from Qixjig, phusis, nature ; that is, visible 
and material nature, the study of actions and reactions which do not 
involve entire and permanent change in the properties of bodies — 
the study of the action of heat, light, electricity, magnetism, gravi- 
tation, etc. on matter.) 

It is necessary, however, to state something more about the phys- 
ical as well as the chemical condition of the molecules of a gas, in 
order that the learner may be prepared for the fact that mixtures of 
certain gaseous elements, in combining to form gaseous compounds, 
diminish considerably in volume. Thus, while a pint of hydrogen 
and a pint of chlorine give a quart of hydrochloric acid gas, 



Hydrogen. 


Chlorine. 



Hydrochloric acid gas. 



two pints of hydrogen and one of oxygen are necessary to produce 
a quart of gaseous water (steam). It will be remembered that two 
volumes of hydrogen and one of oxygen were necessary in a 
previous experiment in which water was formed. 



Hydrogen. 


Hydrogen. 


Oxygen. 



Gaseous water (Steam). 



44 



GENERAL PRINCIPLES OF 



Now, that a pint of hydrogen gas and a pint of chlorine gas should, 
after chemical reaction or rearrangement of the atoms of the mole- 
cules has taken place, form two pints of hydrochloric acid gas is 
quite what we should expect. For, first, the reader by this time is 
not astonished that chemical combination is attended by entire 
change of properties ; and, secondly, the experience of years has led 
him to expect that a pint of one thing added to a pint of another 
gives two pints of the mixture. But that two pints of hydrogen and 
one pint of oxygen should, after combination (and under like con- 
ditions of temperature and pressure), give, not three, but two pints 
of product (steam) is perhaps somewhat astonishing and needs 
explanation. To this end let us picture a few of the molecules of 
hydrogen and as many molecules of chlorine. Draw with a pencil 
on paper several pairs of crosses ( + + ) to represent hydrogen 
molecules, and circles ( O O ) for chlorine molecules, or, if colored 
ink is at hand, red pairs of dots for hydrogen and green for chlorine. 
Or, at once, for facility in printing, let the following pairs of letters 
h h represent a few (say, nine) molecules of hydrogen, and c c mole- 
cules (nine) of chlorine, before combination : 



hh 


hh 


hh 


c c 


c c 


c c 


hh 


hh 


hh 


c c 


c c 


c c 


hh 


hh 


hh 


c c 


c c 


c c 



Then, after combination, we shall have eighteen molecules of 
hydrochloric acid gas : 



h c 


h c 


h c 


h c 


h c 


h c 


h c 


h c 


h c 


h c 


h c 


h c 


h c 


h c 


h c 


h c 


h c 


h c 



But when two volumes of hydrogen and one of oxygen combine 
and give two volumes of steam, the mental picture must be, not that 
of molecules somewhat nearer to each other than before, nor any 
difference in the size of the molecules, but a picture of molecules 
each containing three instead of two atoms ; thus, still using pairs 
of letters, just for the moment, to represent a few (the space will 
allow only twenty-seven) molecules : 



hh 


hh 


hh 


hh 


hh 


hh 











hh 


hh 


hh 


hh 


hh 


hh 


O 








hh 


hh 


hh 


hh 


hh 


hh 


0- 


O 






The twenty-seven molecules (eighteen hydrogen, nine oxygen) 
will, after combination, become eighteen molecules of steam : 



hoh 


hoh 


hoh 


hoh 


hoh 


hoh 


hoh 


hoh 


hoh 


hoh 


hoh 


hoh 


hoh 


hoh 


.hoh 


hoh 


hoh 


hoh 



CHEMICAL PHILOSOPHY. 45 

As already suggested, one's mental picture of a number of mole- 
cules may well give them such a relation to each other as that of 
a number of solar systems in the universe, equally distant from each 
other, and each occupying a similar space, yet one system containing 
a sun and one planet, another a sun and two planets, and so on, or 
even one or more of the planets having one or more moons. Indeed, 
the atoms in some very complex molecules really appear to have very 
much the relation to each other of the sun, planets, and moons of a 
solar system. To indicate such molecules by letters as above would 
of course require more space than is there given to the assumed 
pictures of molecules. 

Here occurs an opportunity that must not be lost of stating a 
mode of reasoning by which a molecule of oxygen (or of many other 
elements) is shown to be a double structure — shown to contain two 
atoms. Five equal-sized bottles are before us — two filled with 
hydrogen, one with oxygen, and two with steam. (The bottles are 
hot enough to prevent the steam condensing to water, and all five are 
at the same temperature.) Apply heat so that all shall be equally 
heated, the three different substances expand equally. Cool equally, 
the contents contract equally. Apply equal pressure to all five, each 
is equally affected. Diminish pressure equally, each portion of the 
three substances equally expands. Gases (practically steam is gas ; it 
is simply not a permanent gas), — gases thus similarly affected must 
be, physically, similarly constructed or constituted (a law which 
will again be referred to on page 53) ; each bottle must contain the 
same number of particles or molecules, and at any one temperature 
and pressure the molecules in each must be equally distant from 
each other. We do not know what actual number or distance, but 
whatever be the number and distance, it is the same for each bottle. 
Say that one million is the number 5 then we shall have a million 
of molecules in the first hydrogen bottle, a million in the second, a 
million in the oxygen bottle, and a million in each of the steam 
bottles. We will cause chemical combination between the two mil- 
lions of hydrogen molecules and one million of oxygen molecules, 
producing (as we have seen) two millions of steam molecules having 
the properties already stated. But a molecule of steam contains an 
atom of oxygen. Hence two millions of steam molecules contain 
two millions of oxygen atoms, which two millions of oxygen atoms 
have been obtained from one million of oxygen molecules. There- 
fore each molecule of oxygen was a double structure — each molecule 
of oxygen contained at least two atoms of oxygen. As Clifford 
says, " You cannot put 50 horses into 100 stables so that there shall 
be exactly the same amount of horse in each stable ; but you can 
divide 50 pairs of horses among 100 stables." 

Thus much respecting the construction of gaseous or vaporous 
matter. Our knowledge of the constitution of liquid and solid 
matter is still more limited. 

With regard to the notation of the subject, it will be sufficient to 

state here that while a symbol usefully represents one volume of any 

gas, a formula of any gas or vapor represents two volumes. By 

remembering this general rule we may, by looking at a formula, 

3* 



46 GENERAL PRINCIPLES OF 

tell how many volumes of constituents were concerned in the forma- 
tion of a compound, and therefore what amount of condensation, 
if any, occurred during the act of formation. By thus reading and 
interpreting the formula for water, H 2 0, we see that two volumes of 
steam (at any temperature) may be obtained from two volumes of 
hydrogen and one volume of oxygen (at the same temperature), 
and thus the extent of condensation when hydrogen and oxygen (at 
a stated temperature) unite to form gaseous water (at the same tem- 
perature) is from three to two. This subject will again be treated of 
in connection with Chemical Combination and the Specific Gravity 
of Gases. 

Further Remarks on General Chemical Notation. 

We may now take an experiment already made as an additional 
example of chemical action, and describe the simplest way of 
expressing the same by notation. When two volumes of hydrogen 
and one of oxygen were caused to combine, the production of flame 
and noise proved that chemical action of some kind had taken place : 
had the experiment been performed in dry vessels, evidence of the 
precise action would have been found in the bedewing produced ^ by 
the condensation of the water on the sides of the tube. Similar 
evidence was afforded on holding a cool glass surface over the 
hydrogen flame. The action is expressed in the following equation : 
2H 2 + 2 = 2H 2 0. 

Instead of this equation, the following diagram may be employed : 




The foregoing aggregation of symbols or shorthand characters, or 
formula, H 2 0, is, then, a convenient picture of the facts that have 
already come before us— viz. that water is formed of the elements 
hydrogen, H, and oxygen, ; moreover, that it is formed of two 
measures or volumes of hydrogen, H 2 , to one of oxygen, ; and, 
thirdly, that the. molecule of water (H 2 0) is formed of two atoms of 
hydrogen (H 2 ) and one of oxygen (0). The formula also fulfils the 
fourth function, of indicating that the two volumes of hydrogen and 
one of oxygen in combining condensed to two volumes of steam. 
That the resulting bulk of steam afterward shrunk most consider- 
ably in condensing to water is another matter altogether — a physi- 
cal and not a chemical result, and due to the approximation of the 
molecules of water after formation. 

Another experiment already performed, illustrating the character 
of the manifestations of chemical force (symbolically noted as fol- 
lows), was that in which the red-hot carbon of wood was plunged 
into oxygen. The evidence of chemical action in that case was 



CHEMICAL PHILOSOPHY. 47 

the sudden inflammation of the carbonaceous extremity of the wood. 
The particles of carbon and oxygen, having intense attraction or 
affinity for each other at that temperature, rushed together so 
impetuously as suddenly to produce a large additional quantity of 
heat, an amount sufficient to cause the particles to emit an intense 
white light. The action is expressed on paper in either of the fol- 
lowing ways : C 2 -f 20 2 = 2C0 2 , or, 



1 C 




o 2 

C0 2 is the formula of the well-known gaseous body commonly 
termed carbonic acid gas. 

The reader should here draw for himself equations or diagrams 
similar to those on pages 42 and 46, and thus show the forma- 
tion of the three other bodies he has already produced — 
namely, phosphoric anhydride (P a 5 ), sulphurous acid gas 
(S0 2 ), and ferrous iodide (Fel 2 ), submitting the same, if pos- 
sible, to a tutor or other authority to assure himself of their 
correctness. 

Note. — In the foregoing experiments several illustrations occur of 
the formation of compounds having the gaseous, liquid, and solid 
conditions, in one of which three forms all matter in the universe 
apparently exists. 

Laws of Chemical Combination (by Weight). 
Chemistry as a science is little more than a hundred years old, 
though very many of the facts and operations we now term " chemi- 
cal" have been known as isolated items of knowledge for centuries. 
Thus the ancient Egyptians made glass, vitriol, soap, and vinegar, 
and the Greeks started the idea that matter was composed of a few 
elements, imagining earth, air, fire, and water to be elements. In 
short, chemistry as an art was already very extensive a hundred or 
more years ago. But the great general principles which interlace 
and bind together separate facts, those which from their extensive 
application and importance are denominated laws, have all been 
brought to light since the year 1770. Scarcely more than a single 
century ago Lavoisier, by invoking the aid of the balance, converted 
the art into the beginning of a science which has since grown by 
ever-recurring leaps and bounds. (Lavoisier was born in 1743 ; he 
was guillotined by Robespierre in 1794. A request for a few days 
of respite to complete some researches was refused on the ground 
that " the republic has no need of chemists.") 

First Law relating to Chemical Combination. 
Between 1785 and 1800, Bryan Higgins, William Higgins, Wen- 
zel, Richter, and Proust made analyses and researches which led up 



48 GENERAL PRINCIPLES OF 

to the following generalization : When compounds unite to form 
definite chemical substances, they always combine in the same propor- 
tions. The curious character of this fact could but be most strik- 
ing, and indeed is so now to the mind receiving it for the first time. 
Thus water (a compound) added to quicklime (a compound) gives 
slaked lime, a perfectly definite chemical substance. But whereas 
sand and water, sugar and water, sand and sugar, and such 
mechanical mixtures may be obtained by adding together the ingre- 
dients in any proportions whatever — say, 90 of sugar and 10 of sand, 
or 10 of sugar and 90 of sand — such a chemical mixture as slaked 
lime (say 100 parts) invariably results from the combination of 75f 
of quicklime and 24 J of water. If a larger proportion than 75f per 
cent, of quicklime be employed, the excess remains as quicklime 
mixed with the slaked lime ; and if more than 24 j per cent, of water 
be used, an excess of water remains with the slaked lime and 
evaporates if the mixture be exposed to the air. Dalton discovered 
that when elements unite to form a definite substance, they, like com- 
pounds, always combine in the same proportions ; and he was the 
first to set forth the law in a manner which was at once clear and 
comprehensive enough to include the former generalization. Thus : 

A definite compound always contains the same elements in the same 
proportions. 

Take another example : Common salt always contains 39+ per 
cent, of the metal sodium to 60f of chlorine, and water always 89 
of oxygen to 11 per cent, of hydrogen (more exactly 88.89 to 11.11). 
As with the quicklime and water, so with the chlorine and sodium 
and the constituents of many (not all) chemical compounds : in such 
cases, if either be added to the other in any quantity beyond stated 
proportions, the excess plays no part whatever in the act of combina- 
tion. (In some cases, as will be seen directly, excess of either plays 
a very simple but very remarkable part.) In short, whether a com- 
pound be made directly from its elements or by the combination of 
other compounds, or indirectly as one of two products of the action 
of substances chemically on each other, whatever be its origin, if it 
is a definite compound it always contains the same elements in the 
same proportions. This is the first of the two laws governing chem- 
ical combinations. 

Second Law relating to Chemical Combination. 

Dalton further made such experimental researches as enabled him 
to lay down a second great law. He found that while many sub- 
stances only united chemically in one proportion, others combined 
in two or even more ; and he studied several such naturally related 
bodies. He found that while carbonic oxide (a gas formed when 
charcoal is burned with a limited supply of air) contains such a pro- 
portionate weight of carbon and oxygen as is represented by (to use 
the simplest figures) 3 and 4, carbonic acid (a gas formed when char- 
coal is burned with excess of air) contains 3 of carbon to exactly 
twice 4 of oxygen. He proved that a similar relation existed between 
two compounds of carbon and hydrogen and between a cluster of 
compounds of nitrogen and oxygen. The first of the latter, to a 



CHEMICAL PHILOSOPHY. 49 

given quantity of nitrogen contains a certain proportion of oxygen ; 
the next, to the same quantity of nitrogen has exactly twice the pro- 
portion of oxygen ; and the others have exactly three, four, and five 
times as much oxygen as the first, the quantity of nitrogen remain- 
ing the same throughout. Dalton thus generalized these facts : 

When two elements unite in more than one proportion, the resulting 
compounds contain, to a constant proportion of one element, simple 
multiple proportions of the other ; or the weights of the constituent 
elements bear some similar simple relation to each other. 

Thus carbonic oxide gas is a definite compound always containing 
fixed proportions of carbon and oxygen, and carbonic acid gas is also 
a definite compound always containing fixed proportions of carbon 
and oxygen. Both thus obey the first law of combination. But 
whereas carbonic oxide contains, or may be made from, 30 parts 
(ounces, grains, or other weights) of carbon and 40 of oxygen, car- 
bonic acid contains, or may be made from, 30 parts of carbon and 
exactly twice 40 of oxygen. 

The second law cannot but be as striking as the first when freshly 
unveiled to the mind. Sand and sugar, or any substances which do 
not act chemically on each other, may be mixed in the proportions 
of 30 to 40, 30 to 80, 30 to 60, or any other quantities ; but if an 
attempt be made to burn 30 parts of carbon in 60 of oxygen, the 
elements will themselves naturally assert their own special combin- 
ing powers, and refuse, so to say, to unite in these proportions : the 
30 of carbon will first combine with 40 of oxygen and form 70 of 
carbonic oxide ; and this gas, which, had it the opportunity, would 
combine with 40 more of oxygen and form carbonic acid gas, finding 
only half that quantity — namely, 20 of oxygen — present, contents 
itself by one half (that is 35 of carbonic oxide) accepting the 20 
of oxygen and becoming carbonic acid gas, while the other half 
remains as carbonic oxide. This is a most wonderful fact. Again, 
if 30 parts of carbon be burnt in more than 80, say 85, of oxygen, 
only 80 will be used, the other 5 remaining as oxygen merely mixed 
with the resulting carbonic acid gas. If we attempt to burn 30 
parts of carbon in less than 40 of oxygen, the oxygen will take up 
three-fourths its weight of carbon and form carbonic oxide, while 
the excess of carbon will remain as carbon. 

Recapitulation. 
Nature does not always permit man to mix things in any propor- 
tions he pleases. She does sometimes. She does if he only stirs 
things together, or if he only uses the attractions of adhesion or 
cohesion in binding the materials together ; but if he employs chem- 
ical attraction, she restricts him to special proportions. That is to 
say, if the things mixed do not attack one another or intimately 
combine, then admixture may be effected in any proportion ; and the 
mixture is a mere mixture, having the mean properties of its com- 
ponents. Examples of such mixtures are seen in compound plasters, 
pill-masses, confections, and plum-puddings. But if the things do 
unite to form not a mere mixture having the mean properties ,of its 
components, but a compound having new and distinct and definite 



50 GENERAL PRINCIPLES OF 

characters of its own, then Nature does not permit man to combine 
the things in any proportion he pleases. The proportion is a fixed 
and constant one ; and if he substitutes proportions of his own, the 
things unite in the proportions fixed by Nature, and the excess he 
has added either remains in its original uncombined condition, or it 
combines with the compound already produced to form a second dif- 
ferent compound. Any one compound — that is, the same com- 
pound — always contains the same elements in the same proportions, 
and can only be made from the same elements in the same propor- 
tions. An attempt to mix the same elements in other proportions 
would result in one of two failures — namely, either the extra pro- 
portion would remain free and uncombined, or it would combine 
and convert the first compound or a portion of it into a different 
compound. The fresh compound thus produced, like the first, and 
indeed like all definite compounds, of course always contains the 
same elements in the same proportions. 

In short (Law 1), any definite compound always contains the same 
elements in the same proportions, and (Law 2) any two elements 
uniting in more than one proportion unite in multiples of that pro- 
portion, and produce so many different definite compounds. Taking 
hydrogen as uniting in proportions of 1, oxygen unites in propor- 
tions of 16 ; that is, 16, twice 16, thrice 16, and so on, never in 
intermediate proportions. Carbon unites in proportions of 12, sul- 
phur of 32, chlorine 35J. Every element (see the table in front of 
the Index) has its combining proportion fixed by Nature. 

The student of chemistry is recommended to accept these two 
great natural facts, great enough to be dignified by the name of 
laivs, in all their inherent solidity and simplicity. Of course he will 
wonder why substances should combine, chemically, only in fixed 
proportions when forming a definite body, and why, when a sub- 
stance combines in more than one proportion to form different 
definite bodies, the proportions should only be multiple proportions, 
and will gladly hail the extremely ingenious and useful explana- 
tion of these truths suggested by Dalton. (See foregoing and fol- 
lowing paragraphs on the theory that matter is built up of atoms.) 
But man has not yet succeeded in so questioning Nature as to gain 
from her a satisfactory answer to such questions ; and until he does 
succeed, any hypothesis, even Dalton's, should be held intelligently, 
but not too tightly. The facts themselves, however, should be 
grasped with the student's utmost tenacity. 

Reciprocal Proportions. — Careful consideration of the foregoing 
two great laws relating to chemical combination leads to an import- 
ant truth— namely : The proportions in which two elements unite 
with a third are the proportions {or simple multiples or submultiples 
of the proportions) in which they unite with each other. Thus oxy- 
gen in proportions of 16 unites with hydrogen, and carbon in pro- 
portions of 12 unites with hydrogen ; therefore 16 and 12 are the 
proportions in which oxygen and carbon will unite with each 
other.* 

* See Axiom 1 in Hawtrey's Introduction to the Elements of Euclid, 



CHEMICAL PHILOSOPHY. 51 

The Atomic Theory. 
The laws which Dalton so largely aided to unveil — two grand 
and wonderful truths — he explained and correlated by a simple and 
beautiful hypothesis (1803 to 1808). Why should any given com- 
pound always contain the same elements in such absolutely fixed 
proportions? Why, when an element combines in more than one 
proportion, forming more than one given compound, should it com- 
bine in exactly multiple proportions? The first answer must be 
that no one knows ; that is to say, that we are unable to refer to 
any demonstrable fact for the answer. But a century ago the same 
Englishman devised an explanation that has satisfied the world. 
Dalton' s explanation was that matter was not infinitely divisible, but 
composed of minute particles or atoms having an invariable character. 
In the words of Wurtz, u To an old and vague notion he attached an 
exact meaning by supposing that the atoms of each kind of matter 
possess a constant weight, and that combination between two kinds of 
matter takes place not by penetration of their substance, but by juxta- 
position of their atoms. 1 ' 1 Dalton raised the old Grecian hypothesis 
(see page 37) to the dignity and importance of theory, and gave to 
it a quantitative foundation. 

Under this "atomic theory" carbonic oxide is a definite com- 
pound always containing the same elements in the same propor- 
tions, because each particle of it is composed of an atom of carbon 
and an atom of oxygen chemically united, the weights of the atoms 
being in the proportion of 3 and 4 ; that is, having a constant 
weight of 12 and 16, as we now believe. Carbonic acid gas is also 
a definite compound always containing the same elements in the 
same proportions, and the proportion of oxygen is just double that 
in carbonic oxide, because each particle of it is composed of an 
atom of carbon (weighing 12) and two atoms of oxygen (each 
weighing 16). 

The healthily constituted student-mind asks, " Why an element 
should unite in exactly multiple proportions if it forms several com- 
pounds?" Because those compounds are " made" of atoms, which, 
being indivisible, must, if they unite at all, unite 1 to 1, 2 to 1, 3 to 
1, and so on. With such an explanation, although only one expla- 
nation, the healthily constituted mind gains desired satisfaction. 



( 12 A 16 





Imaginary Pictures of Molecules of Carbonic Oxide Gas and Carbonic Acid Gas.* 

Longmans & Co. — a book recommended to any student who is not 
familiar with the mode of reasoning termed geometrical. 

*The size of atoms, their shape, their absolute weight— whether or 
not they are in actual contact — whether or not they are fixed in relation 
to each other, free to move about each other or in a constant state of 
motion — and whether or not the chemical force actuates them as the 
force of gravitation influences our earth and moon and solar systems, 
are matters of which, at present, we know almost nothing. The two 
pictures are not intended to convey any impression that the following 
formulae do not give : CO or OC, OCO or CO2. 



\ 
52 GENERAL PRINCIPLES OF 

Again, the facts that with 12 of carbon oxygen unites in the 
proportion of 16 or a multiple of 16 ; that with 12 of carbon sulphur 
unites in the proportion of 32 or a multiple of 32 (the liquid known 
as carbon disulphide is a chemical compound of 12 of carbon to 
twice 32 of sulphur) 5 and, thirdly, that oxygen and sulphur unite 
in proportions of 16 and 32, — are at once explained on the assump- 
tion that these elements exist in atoms which have the respective 
weights mentioned. Existing in indivisible particles (atoms), which 
weigh 16, 12, and 32, oxygen, carbon, and sulphur must unite in 
indivisible weights of 16, 12, and 32. 

Atomic Weights. 

What has just been stated respecting two or three elements is 
true of all the elements. It is a fact that when elements unite with 
one another in the peculiar and intimate manner termed chemical, 
they do not combine in the haphazard proportions of a mere mix- 
ture, but in one fixed and constant proportion. Such proportions 
or weights represent, according to Dalton, the weights of their 
atoms. Oxygen unites with other elements in proportions of 16 ; 
therefore 16 is the weight of the atom of oxygen. Chlorine unites 
with other elements in proportions of 35J, therefore 35J is the 
atomic weight of chlorine. And for a similar reason the atomic 
weight of hydrogen will be 1, carbon 12, sulphur 32, nitrogen 14, 
and iodine 127. Of course it will be understood that these are the 
relative weights of atoms, for we cannot know the absolute weights. 
All that is known is that the chlorine atom, for instance, is 35.5 
times as heavy as the hydrogen atom, whatever the absolute weight 
of the latter may be, and the iodine atom 127 times as heavy. The 
quantity of metal which with 35.5 of chlorine will form a chloride, 
and with twice 35.5 a second chloride (dichloride or bichloride), will 
require 127 of iodine to form an iodide, and twice 127 of iodine to 
form a second iodide (a diniodide or biniodide).* In other words, 
the atomic weight of an element is the ratio of the weight, quantity 
of matter, or mass of an atom to the weight, quantity of matter, or 
mass of an atom of hydrogen. 

Notes on Notation. — A fourth function of a symbol is to represent 
atomic weight. Thus the symbols H, CI, 0, etc. not only perform 
the offices of representing (a) names, (5) single volumes, and (c) 
single atoms, but (d) definite weights of the respective elements : 
H = 1, CI = 35.5, = 16, I = 127, N = 14, K = 39, etc. 

Laws of Chemical Combination (by Volume). 

In 1809, Gay-Lussac showed it to be a fact that when gaseous 
elements unite with one another in the intimate manner termed 
chemical, they do not combine in the haphazard proportions (that 
is, proportions by measure or volume) of a mere mixture, but in 

* Only the atomic weights of the above and a few of the chief metallic 
elements need be committed to memory ; others can be sought out as 
occasion may require. A table of combining proportions of elements, or 
atomic weights, is given at the end of the volume, in front of the Index, 



CHEMICAL PHILOSOPHY. 53 

constant proportions in the case of any single definite compound, 
and in simple multiple proportions in cases where two elements 
form more than one definite compound. He thus proved that the 
laws respecting the constancy of weight with which elements com- 
bine hold good with reference to volume, at all events in those cases 
in which elements exist in or can be made to assume the gaseous 
condition. A volume of hydrogen gas and an equal one of chlorine 
gas give hydrochloric acid gas. Two volumes of hydrogen and one 
of oxygen give water vapor or' steam. Such volumes or simple 
multiples are alone the proportions by bulk in which elements com- 
bine. If any excess of either gas be mixed and combination at- 
tempted, only the stated proportions really combine, the excess 
remaining unaltered. Further, following Gay-Lussac, on weighing 
these similar and equal volumes of hydrogen, chlorine, and oxygen 
we find that chlorine is 35.5 times as heavy as hydrogen, and oxy- 
gen sixteen times as heavy as hydrogen. 

Avogadro's "Law." — Avogadro in 1811 and Ampere in 1814, 
reasoning on the fact that all gases are similarly affected by varia- 
tions of pressure (Boyle, 1662, verified by Mariotte) and temperature 
(Charles), (see also page 45), concluded that all gases must be 
similarly constituted (similarity in properties always indicating 
similarity in character or nature — a mode of reasoning or deducing 
or inferring that even children soon naturally adopt in dealing 
with everything that appeals to their senses) ; in other words, that 
if equal volumes of gases be taken under like conditions, each will 
contain the same number of molecules, similar in size and equally 
distant apart. The deduction is obvious. The weights of molecules 
of gaseous elements [that is, of pairs of atoms, and therefore of atoms 
themselves) must differ to the extent that the weights of equal volumes 
of those elements dijfer. Equal volumes of hydrogen, chlorine, and 
oxygen, weighing, respectively 1, 35.5, and 16, and each of these 
volumes containing an equal number of molecules, each formed of 
two atoms, it follows that the relative weights of the atoms will be 
1, 35.5, and 16. 

It will thus be seen that the weight of the volume in which an 
element combines, and the actual weight in which it combines, irre- 
spective of volume, are identical. For instance, we should find by 
experiment that, as a simple matter of fact, oxygen unites with other 
elements in proportions of 16 by. weight, while hydrogen combines 
in proportions of 1. Turning, then, to experiments on the volumes 
in which hydrogen or oxygen combine, and having ascertained 
those volumes, and then having weighed them, we should find that 
the oxygen volume weighs 16, while the hydrogen weighs 1. In 
compounds in which proportions of 1 grain of hydrogen were 
found oxygen would be found in proportions of 16 grains. In gase- 
ous compounds in Which hydrogen existed in proportions of, say, 
27 ounces by measure, oxygen would be found in proportions of 27 
ounces by measure : the 27 ounces of hydrogen would be found to 
weigh 1 grain, and the 27 ounces of oxygen to weigh 16 grains. 

Thus the two great facts or laws respecting chemical compounds 
which Dalton laid down, by ascertaining the exact weights in which 



54 GENERAL PRINCIPLES OF 

bodies combine, Gay-Lussac confirmed by experiments on the exact 
volumes in which elements combine. Further, Gay-Lussac' s ex- 
periments and Avogadro's reasoning strongly supported Dal ton's 
theory of atoms. 

Recapitulation. 

What are atomic weights or combining weights? First, they are 
represented by the smallest portion (relative to 1 part of hydrogen) 
in which an element migrates from compound to compound. Thus, 
1 part by weight of hydrogen can be eliminated from 18 similar 
parts of water by action of certain metals, leaving 1 of hydrogen 
and 16 of oxygen combined with the metal. From the latter com- 
pound 1 more of hydrogen is eliminated by a second experiment with 
more metal, leaving 16 of oxygen combined with the metal. In 
these and other well-known reactions 16 parts of oxygen take part 
in the various operations 5 16, therefore, is the probable atomic 
weight of oxygen 5 and so with other elements and radicals. Secondly, 
the weight of the atoms, or the atomic weights, of the gaseous ele- 
ments already studied must differ from each other to the extent that 
equal volumes of those elements differ in weight. For equal volumes 
contain an equal number of molecules equal in size (Avogadro and 
Ampere), and each molecule of an element is composed of two atoms ; 
so that equal volumes of the gaseous elements contain an equal 
number of atoms. Now, bulk for bulk, chlorine is thirty-five and a 
half (35.5) times as heavy as hydrogen 5 so that the molecule of 
chlorine must be 35.5 times the weight of the molecule of hydrogen. 
And as the molecules of chlorine and hydrogen contain two atoms 
each, the atom of chlorine must be 35.5 times as heavy as that of 
hydrogen. The actual weight of atoms can never be ascertained ; 
but that is of little consequence if we can only determine, with 
exactitude, their comparative weights. Comparing, then, all atomic 
weights (sometimes obscurely termed equivalents) with each other, 
and selecting hydrogen as the standard of comparison (because it is 
the lightest body known, and therefore, probably, will have the 
smallest atomic weight), and assigning to it. the number 1, we see 
that the atomic weight of chlorine will be represented by the number 
35.5. By parity of reasoning the atomic weight of oxygen is 16, 
for oxygen is found, by experiment, to be sixteen times as heavy as 
hydrogen. Similarly, the atomic weight of nitrogen is found to be 
14. The atomic weight of carbon is 12 — not because its vapor has 
been proved to be twelve times as heavy as hydrogen, for it has never 
yet been converted into the gaseous state, but because no gaseous 
compound of carbon which has been analyzed has been found to 
contain in 2 volumes (1 of which, if hydrogen, would weigh 1 part) 
less than 12 parts of carbon. (For an explanation of this reference 
to two volumes see next page.) 

By thus weighing equal volumes of gaseous elements or equal 
volumes of gaseous compounds of non-volatile elements, and ascer- 
taining by analysis the proportion of the non-volatile element, whose 
atomic weight is being sought, to the volatile element, whose atomic 
weight is known, the atomic weights of a large number of the 



CHEMICAL PHILOSOPHY. 55 

elements have been determined. Some of the elements, however, do 
not form volatile compounds of any kind : the stated atomic weights 
of these elements, therefore, are at present simply the proportions 
by weight in which they combine with or displace elements whose 
atomic weights have been determined, the proportions being in most 
cases checked by isomorphic considerations and the relation of the 
element to other €orces, especially heat.* ( Vide infra.) 

Molecular Weight and Molecular Volume. 

The weight of a molecule.is simply the sum of the weights of its 
atoms 5 thus, 

H 2 = 2, 2 = 32, Cl 2 == 71, H 2 = 18, HC1 = 36.5. 

The foregoing formulae are molecular formulae, or two-volume for- 
mulce. It will be remembered that one volume of hydrogen and one 
of chlorine gave two of hydrochloric acid, and that two of hydrogen 
and one of oxygen gave two of steam, etc. 

Molecular Volume. — If the quantities just mentioned be weighed 
out (in grains or other weights), or if the molecular weights of any 
gases or liquids be taken and exposed to similar (high) temperatures 
and pressures, they ivill be found to occupy the same volume. Con- 
versely, if equal volumes of gases or vapors be measured out, and 
then the whole weighed, the resulting figures (all referred to 2 of 
hydrogen as a starting-point or standard) are the molecular weights 
of the respective substances. For equal volumes contain equal 
numbers of molecules (Avogadro). Why? Because equal volumes 
have equal physical properties (Boyle, Charles) ; and various things 
which have similar properties are by that fact shown to be similar 
things — the mode of reasoning which from childhood onward 
teaches us that two separate things (e. g. two pennies) are similar 
things. In the cases now being considered the things differ chem- 
ically, for they have entirely different chemical properties ; they are 
not similar chemically : the point is that, having similar physical 
properties, they are similar physically ; whatever the number of 
molecules in a volume of one of the gases or vapors, there must be 
a similar number in similar volumes of the others ; therefore the 
differences in the weights of tangible volumes are the differences in the 
weights of the intangible molecules. This subject will again be re- 
ferred to in connection with quantitative analysis {vide Index, "Mo- 
lecular Weight") ;. at present the following illustration will suffice: 

* Isomorphous bodies (la-os, isos, equal, and m°p<M, morphe, form) are those 
which are similar in the shape of their crystals. This identity in crys- 
talline form is so commonly associated with similarity of constitution 
that non-crystalline substances resembling each other in structure are 
often regarded as isomorphous. When one element unites with another 
in more than one proportion, and its atomic weight is so far uncertain, 
the isomorphism of either of its compounds with some other compound 
of known constitution is usually accepted as evidence of some value as 
to which proportion is atomic, especially if the compounds are so closely 
isomorphous that a crystal of either will "grow" in a solution of the 
other. The specific heat of elements will be treated of subsequently. 



56 GENERAL PRINCIPLES OF 

A volume of hydrogen (about 54 fluidounces) which at a temperature 
of, say, 300° F. or 400° F., and common atmospheric pressure would 
weigh 2 grains, would in the case of vapor of water (steam) weigh 
18 grains. Hence we are justified in considering — indeed, compelled 
to consider — the molecule of water to contain 2 atoms of hydrogen 
(= 2) and one of oxygen ( = 16), and its formula to be H 2 ( = 18), 
and not H 4 2 , in which case its vapor would be twice as heavy as it 
really is found to be. 

Construction of Formulae. — The composition of hydrochloric acid 
(HC1), water (H 2 0), ammonia gas (NH 3 ), carbonic acid gas (C0 2 ), or 
any other compound, as well as the weight of an element that may 
be concerned in its formation, cannot be ascertained by actual ex- 
periment until the student is far advanced in practical chemistry — 
until he is able to analyze not only qualitatively, but, by help of a 
balance, quantitatively. The percentage composition of a chemical 
substance having been determined by quantitative analysis, its 
formula is constructed by the aid of the foregoing and other theo- 
retical considerations. The correctness of such formulae can be 
verified by expert analysis, but must be taken for granted by learners. 
This subject will again be referred to in the latter part of this 
Manual. 

QUANTIVALENCE OP ATOMS, OR VALENCY. 

Turning from the weights of atoms, their chemical value may now 
be considered, or their quantivalence. The exchangeable chemical 
value of atoms in relation to each other may be compared to the 
exchangeable commercial value of coins. As compared with a 
penny, a groat is four-valued ; as compared with hydrogen, carbon 
is quadrivalent. Here, again, hydrogen is conventionally adopted 
as the standard of comparison. An oxygen atom in its relations to 
an atom of hydrogen is bivalent (biv'a-lent, of double worth, from 
bis, twice, and valens, being worth) ; an atom of it will displace two 
atoms of hydrogen or combine with the same number ; nitrogen is 
usually trivalent (triv / a-lent, from tres, three, and valens), while 
carbon is quadrivalent (quad-riv / a-lent, from quatuor, four, and 
valens). Chlorine, iodine, and bromine, as well as potassium, sodium, 
and silver among the metals, are, like hydrogen, univalent (u-niv'a- 
lent, fromimus, one, and valens). Barium, strontium, calcium, mag- 
nesium, zinc, cadmium, mercury, and copper, like oxygen, are 
bivalent. Phosphorus, arsenium, antimony, and bismuth, like 
nitrogen, usually exhibit trivalent properties, but the composition of 
certain compounds of these five elements shows that the several 
atoms are sometimes quinquivalent (quin-quiv / a-lent, quinquies, five 
times, and valens). Gold and boron are trivalent. The atoms of 
silicon (the characteristic element of flint and sand), tin, platinum, 
and lead resemble carbon in being quadrivalent. Sulphur, chromium, 
manganese, iron, cobalt, and nickel are sexivalent (sex-iv'a-lent, 
from sex, six, or sexies, six times, and valens), but frequently exert 
only bivalent, trivalent, or quadrivalent activity. This quantivalence 
(quant-iv / a-lence, from quantitas, quantity, and valens), also termed 
atomicity (maximum quantivalence), dynamicity, equivalence, and, 



CHEMICAL PHILOSOPHY. 57 

simply, valency, of atoms, may be ascertained at any time on refer- 
ring to the Table of the Elements at the end of this volume, where 
Roman numerals, i, n, in, iv, v, vi, are attached to the symbols of 
each element to indicate! atomic univalence, bivalence, trivalence, 
quadrivalence, quinquivalence, or sexivajence. Dashes (H/, // , 
N /// ) similar to those used in accentuating words are often used in- 
stead of figures in expressing quantivalencc. The quantivalence of 
elements, as they one after another come under notice, should be 
carefully committed to memory, for the composition of compounds 
can often be thereby predicated with accuracy and remembered with 
east;. For instance, the hydrogen compounds of chlorine, CV, oxy- 
gen, // , nitrogen, N /A/ , and carbon, C /7// , will be respectively 
H'CK, H / 2 // , H^N'", and H / 4 C //// — one univalent atom, li, 
balancing or saturating one univalent atom, CI'; two univalent 
atoms, IF.,, and one bivalent atom, // , saturating each other ; three 
univalent atoms, IFg, and one atom having trivalent activity, N T/// , 
saturating each other ; and four univalent atoms, II^, and one quad- 
rivalent atom, C //// , saturating each other. Carbonic acid gas, 
C IV 0" 2 , again, is a saturated molecule containing, in one molecule, 
one quadrivalent and two bivalent atoms. 

The subject of quantivalence will be further explained after the 
first six metals have been studied, when abundant illustrations of 
quantivalence will have occurred. 



DEFINITIONS. 



Chemistry is the study of the force by which matter becomes per- 
manently altered in properties. 

The Chemical Force, like other forces, cannot itself be described, 
for, like them, it is only known by its effects. It is distinguished 
from other forces by the facts that (a) it produces an entire change 
of properties in the bodies on which it is exerted, and that (b) it is 
exerted only between definite weights and volumes of matter. Like 
the force of cohesion, which is the name given to the attraction 
which molecules have for each other, and which is great in solids, 
small in liquids, and apparently absent in gases, and like the force 
of adhesion, which is the name; given to the attraction which amass 
of molecules has for another mass, the chemical force, acts only 
within immeasurable distances ; indeed, inasmuch as the chemical 
force appears to reside in atoms — that is to say, is exerted inside a 
molecule, while all # other forces affect entire molecules — the chemical 
force may be said to be distinguished (c) by being exerted within 
a smaller distance than that at which any other force is exerted. 

An Element is a substance which cannot by any known means be 
resolved into any simpler form of matter. 

An Atom of any element is a particle so small that it undergoes no 
further subdivision in chemical transformations. 

A Molecule is the smallest particle of matter that can exist in a 
free state. 

A Mere Mixture of substances is one in which each ingredient 
retains its properties. 



58 GENERAL PRINCIPLES OF 

A Chemical Compound is one in which definite weights of constit- 
uents have undergone an entire change of properties. A " com- 
pound " in pharmacy is an intimate mixture of substances, but still 
only a mixture : it is not a chemical compound ; the ingredients have 
not entered into chemical .union or combination. 

Combustion is a variety of chemical combination, a variety in 
which the chemical union is sufficiently intense to produce heat and, 
generally, light. 

The Law of Diffusion is one under which gases mix with each 
other at a rate which is in inverse proportion to the square roots of 
their relative weights ; that is, irrespective of, and even in spite of. 
their comparative lightness or heaviness. 

A Chemical Symbol is a capital letter or a capital and one small 
letter. It has four functions — namely : 

i. It is shorthand for the name of the element. 

2. It represents one atom of the element. 

3. It stands for a constant weight of the element — the atomic 

weight or combining weight. 

4. Symbols represent equal and single volumes of gaseous ele- 

ments. 
A Chemical Formula represents (1) a molecule either of an ele- 
ment or of a compound. It has four other functions : 

2. It indicates at a glance the names of the elements in the 
molcule. 

3. Its symbol, or symbols, together with a small figure attached 

to the foot of any symbol, show the number of atom?, in the 
molecule. 

4. It stands for a constant weight of a compound — the molecular 

weight — the sum of the combining weights or of the weights 
of the atoms in the molecule. 

5. It represents two volumes of the substance (if vol atiliz able) in 

the state of gas or vapor, and the number of volumes of gas- 
eous elements from which two volumes of any gaseous com- 
pound were obtained. 

A Chemical Equation or a Chemical Diagram is a collection of 
formulae and symbols so placed on paper as to form a picture or 
illustration of the state of things before and after that metathesis 
(interchange) of atoms of molecules which results in the formation 
of molecules of new substances. 

A Solid is a substance the molecules of which are more or less 
immobile, though probably not in absolute contact. 

A Liquid is a substance the molecules of which so freely move 
about each other that it readily assumes and retains the form of 
any vessel in which it is placed. 

A Gas is a substance the molecules of which are so far apart that 
they seem to have lost all attraction for each other, and, indeed, to 
have acquired the property of repulsion to such an extent that they 
are only prevented from receding to a still greater extent by the 
pressure of surrounding matter. Motion is especially characteristic 
of the molecules of gaseous fluids. 



CHEMICAL PHILOSOPHY. 59 

The Two Laws regulating Chemical Combinations 
{either by weight or volume). 

First. The Law of Definite Proportions. — A definite compound 
always contains the same elements and the same proportions of 
those elements — by weight or by volume. 

Second. The Law of Multiple Proportions. — When two elements 
unite in more than one proportion by weight or by volume, they do 
so in simple multiple of that proportion, forming different com- 
pounds, each of which, as regards definiteness of composition, of 
course obeys the first law. 

Reciprocal Proportions. — The proportions in which two elements 
unite with a third are the proportions in which they unite with 
each other. 

Atomic Weights are, first, the proportions in which elements are 
found to combine with each other by weight. (The figures showing 
these proportions are purely relative, but all chemists agree to make 
this relation fixed by giving the number 1 to hydrogen.) Secondly, 
they are the weights of equal volumes of gaseous elements (relative 
to 1 of hydrogen). 

Molecular Weights. — These are the weights of equal volumes of 
gases or vapors under equal circumstances of temperature and pres- 
sure, and relative not to 1, but to 2 of hydrogen. In the case of 
non-volatile bodies molecular weight is deduced from the observed 
analogies of the bodies with those whose molecular weight admits 
of proof. 

Quantivalence of Atoms. — The chemical value for work of an 
atom relative to one of hydrogen. (Caution. — Quantivalence gives 
no clue to that varying intensity of union of atoms which results in 
varying stability of compounds.) 



The Learner is recommended to read the foregoing paragraphs 
on the General Principles of Chemical Philosophy carefully 
once or twice, then to study (experimentally, if possible) 
the following pages, returning to and reading over the 
General Principles from time to time until they are thoroughly 
comprehended. 

Minor principles of Chemical Philosophy will be found scattered 
throughout the following pages. (Also vide Index, under the word 
" Principles.") 

Students of pure Chemistry, especially when fairly well acquainted 
with chemical facts, will also find the principles of Chemistry, 
including the probable constitution as distinguished from the mere 
composition of chemical substances, fully set forth in the larger 
text-books. 

QUESTIONS AND EXEECISES. 

What do you understand by chemical action ? Give examples.— How 
is the chemical force distinguished from other forces ? — Adduce evidence 



60 THE ELEMENTS AND THEIR COMPOUNDS. 

that elements exist in compounds — that ferrous sulphide, for instance, 
still contains particles of sulphur and iron, though it possesses properties 
so different from those elements. — Define the term "atom." — What con- 
dition is essential for the manifestation of chemical force ? — Can an atom 
exist in an uncombined state ? and when are atoms most potent to enter 
into chemical combination ? — What is a molecule ? — How may the results 
of chemical reactions be expressed on paper? — Enumerate the functions 
of a symbol. — Give the additional functions of a chemical formula. — 
Describe by a diagram or an equation the reaction which ensues when 
red-hot charcoal is plunged into oxygen gas. — Draw diagrams represent- 
ing the formation of P2O5, SO2, and Fel2, respectively. — Enumerate the 
differences in the physical conditions of the molecules in a solid, a liquid, 
and a gas. — State the law of constant proportions. — State the law of 
multiple proportions. — State the principle of reciprocal proportions. — Give 
illustrations of the above laws. — Describe the origin and use of the 
atomic theory. — What do you understand by the atomic weight and the 
molecular weight of an element ? — Representing the weight of an atom of 
hydrogen as 1, what will be the atomic weights of carbon, sulphur, nitro- 
gen, and iodine ? Give reasons for considering the stated weights to be 
correct. — In what proportion, by volume, do elements in the gaseous 
state chemically combine? — What relation exists between the combining 
volumes of elements in the gaseous state and their atomic weights? 
Give the explanation for this. Is there any difference between the 
molecular volumes of simple and of compound gases? — Define isomor- 
phism. — Explain the value of isormorphism as evidence of atomic weight. 
What is to be understood by the quantivalence of atoms? Give examples 
of univalent, bivalent, trivalent, and quadrivalent atoms.— How may 
the quantivalence of an element be expressed in its atomic symbol ?— Give 
formulae in which the quantivalence of one atom is saturated by the 
combined quantivalence of others. 

The reader is also recommended to question himself, or be questioned, 
on the " definitions" given on pp. 57-59. 



THE ELEMENTS AND THEIR COMPOUNDS. 

Having thus obtained a general idea of the nature of such ele- 
ments as have special interest for the medical and pharmaceutical 
student, and which, indeed, are all with which any student of Chem- 
istry should at present occupy his attention, we may pass on to con- 
sider in detail the relation of the elements to each other. The 
elements themselves, in the free condition, are seldom used in 
medicine, being nearly always associated — bound together by the 
chemical force ; in this combined condition, therefore, they must be 
studied — inorganic combinations first, organic afterward. Most 
compounds met with in the mineral kingdom may be regarded as 
containing two parts or roots, two radicals — the one usually metal- 
lic, or, to speak more generally, basylous ; the other commonly a 
non-metallic, simple or complex, acidulous radical. In the following 
pages the basylous radicals, or metals, will be considered first, the 
acidulous radicals afterward. (They will follow the chemistry of 
compounds, many of which have not so simple a constitution as 
that just indicated.) Each radical w T ill be studied from two points 
of view, the synthetical and the analytical ; that is to say, the prop- 
erties of an element on which the preparation of its compounds 



POTASSIUM. 61 

depends will be illustrated by descriptions of actual experiments, 
and thus the principles of chemistry and their applications to med- 
icine and pharmacy be simultaneously learnt; then the reactions 
by which the element is detected, though combined with other sub- 
stances, will be performed, and so the student be instructed in 
qualitative analysis. Synthetical and analytical reactions are, in 
truth, frequently identical, the object with which they are performed 
giving them synthetical interest on the one hand or analytical 
interest on the other. 

A good knowledge of Chemistry may be acquired synthetically 
by preparing considerable quantities of the salts of the different 
metals, or analytically by going through a course of pure qualita- 
tive analysis. But the former plan demands a larger expenditure 
of time than most students have to spare, while under the latter 
system pupils generally lose sight of the synthetical interest which 
attaches to analytical reactions. Hence the more useful system, 
now offered, of studying each metal, etc. from both points of view, 
time being economized by the operator preparing only small speci- 
mens of compounds. 



Chemical synthesis and analysis, thoughtfully and conscientiously 
followed, without hurry and mere superficial consideration, but, of 
course, without undue expenditure of time, will insensibly carry 
the principles of Chemistry into the mind, and fix them there 
indelibly. 

Note. — As a general rule, throughout this Manual paragraphs 
describing experiments to be performed are distinguished from 
paragraphs containing matter merely to be read by being printed in 
somewhat larger type. 



Elements and their Atomic Weights, etc. — For an alphabetical 
list see the two pages immediately preceding the Index at the end 
of this volume. 



THE BASYLOUS RADICALS. 



POTASSIUM. 



Symbol, K. Atomic weight, 39. 

Formula, K 2 . Probable molecular weight, 78. 

Memoranda. — The chief sources of potassium salts'* are the chlo- 
ride found at Stassfurt, in Prussia, as the mineral Carnallite (KC1, 

* The ill-defined term salt includes most solid definite chemical sub- 
stances, but more especially those which assume a crystalline form. 
4 



62 THE METALLIC RADICALS. 

MgCl 2 , 6H 2 0) ; Kainite, a double potassium and magnesium sul- 
phate, with magnesium chloride, also occurring among the Stassfurt 
minerals ; the nitrate, found in soils, especially in warm countries ; 
and the compounds of potassium existing in plants. The vegetable 
salts of potassium are converted into carbonate (other salts are 
present) when the wood or other parts are burned to ashes. If the 
ashes be lixiviated with water and the solution evaporated to dry- 
ness, the residue when fused constitutes crude potashes. The res- 
idue, calcined on the hearth of a reverberatory furnace till white, 
gives the product termed pearlash, or impure potassium carbon- 
ate. Large quantities of carbonate are thus produced in North 
America and Russia, and, latterly, from the sugar beet-root marc 
in France. From the native chloride, and from the carbonate 
purified by treating the pearlash with its own weight of distilled 
water, filtering, and evaporating the solution so formed until it 
thickens, and stirring constantly, " so as to form a granular salt'' 
(Potassii Carbonas, B. P., " K 2 C0 3 , with about 16 per cent, of water 
of crystallization''), nearly all other compounds of potassium are 
made. Exceptions occur in cream of tartar (Potassii Bitartras, 
U. S. P.), which is the more or less purified natural potassium salt 
of the grapevine, and in potassium nitrate. Potassium is a con- 
stituent of between forty and fifty chemical or galenical preparations 
of the pharmacopoeias. 

Potassium carbonate (Potassii Carbonas, U. S. P.) is a white 
crystalline or granular powder, insoluble in alcohol, very soluble 
in water, rapidly liquefying in the air through absorption of moist- 
ure, alkaline and caustic to the taste. It loses all water at a red 
heat. The official salt should contain 95 per cent, of real potassium 
carbonate (K 2 C0 3 ). 

Preparation. — Potassium itself is isolated with some difficulty by 
distilling a mixture of its carbonate and charcoal, or by Castner's 
method (see Sodium). It rapidly oxidizes in the air, hence is always 
kept below the surface of mineral naphtha, a liquid containing no 
oxygen. It crystallizes in octahedra. 

Quantivalence. — The atom of potassium is univalent, K'. 

Reactions having (a) Synthetical and (b) Analytical Interest. 

(a) Synthetical Reactions. 

These are utilized in making preparations of potassium. The word 
synthesis is from avvdeotc (sunthesis). a putting together; analysis, 
from avalvu (analuo), to resolve. 

Potassium Hydrate. 

Synonyms. — Caustic Potash ; Potassium Hydroxide ; Potassa ; 
Hydrate of Potassium. 

First Synthetical Reaction. — Boil together, for a few minutes, 
in a basin, 5 or 6 grains of potassium carbonate (K 2 C0 3 ) and 
a like quantity of slaked lime (Ca2HO) with a small quantity 
of water. Set the mixture aside till all solid matter has subsided. 



POTASSIUM. 63 

This liquid is a solution of caustic potash, or potassium hydrate 
(KHO). Made of a prescribed strength, about 5 per cent., it forms 
the Liquor Potassce, U. S. P. 

The mixture is known to be boiled long enough when a little of 
the clear liquid, poured into a test-tube and warmed, gives no effer- 
vescence on the addition of an acid (sulphuric, hydrochloric, or 
acetic) — a test whose mode of action will be explained hereafter. 

In the United States Pharmacopoeia the potassium carbonate for 
this operation is directed to be obtained by boiling a solution of 
the bicarbonate until effervescence ceases ; that is, until the bicar- 
bonate is almost entirely converted into carbonate. 

Best Method of Expressing Decomposition. — This will be easy of 
comprehension if what has already been stated concerning symbols 
and formulae on pp. 40 to 42 and 46 and 47 has been carefully and 
thoughtfully considered. The best means of showing on paper the 
action which occurs when chemical substances attack each other is 
by the employment either of equations or diagrams setting forth 
the formulas of the molecules concerned in the reaction. In an 
equation the formulae of the salts used are written on one line, the 
sign of addition (4-) intervening ; the sign of equality (=) follows, 
and then the formulae of the salts produced, also separated by a 
plus sign (+)• Thus : 

K 2 C0 3 + Ca2HO = 2KHO + CaC0 3 . 
In this reaction (the operation just performed) the metals of (the 
molecules of) the two salts change places : from K 2 C0 3 and Ca2HO 
there are produced CaC0 3 and KHO (two molecules 2KHO) ; from 
potassium carbonate and calcium hydrate there result calcium car- 
bonate (the insoluble portion) and potassium hydrate (in solution).* 

In constructing a diagram or pictorial illustration of a chemical 
reaction (the reaction, for instance, just described), first the formulae 
of the salts used are written under each other on the left side of the 
leaf of a note-book, thus : 

K 2 C0 3 



Ca2HO 

Such formulae are, in this Manual, always given with the descrip- 
tion of the reaction. Secondly, on the right is then written the 
formula of the chief substance produced, thus: 

* If the student is already accustomed to the use of ordinary equa- 
tions, he may pass on to Note 1 on p. 65 ; if not, the author would 
strongly recommend the temporary employment of diagrams for express- 
ing chemical changes. ' Indeed, the occasional use of graphic equations 
or diagrams is of advantage to all students. For while an equation or a 
diagram equally well records the formulae of the salts concerned in the 
whole reaction, the diagram alone suggests the mode in which its writer 
believes the respective atoms to change their positions. In the para- 
graphs succeeding the above, detailed explanations are given respecting 
the use and construction of diagrams. 



64 THE METALLIC RADICALS. 

K 2 C0 3 KHO 

Ca2HO 

Thirdly, the formation of this chief body under consideration — that 
is to say, both the origin of its elements and their destination — is 
traced out by the help of brackets and letters (which show the 
source of the elements) and converging lines (which suggest the 
approach and final union of those elements), thus : 



K 9 C0, 




KHO 



Ca2HO 



| HO 

For the next stage (at other stages, perhaps, in other reactions) the 
reader's own intelligent power of thought and reflection must come 
into exercise. He must reason somewhat as follows : " I am con- 
verting, and entirely converting, a quantity of potassium carbonate 
into potassium hydrate. A molecule, the smallest quantity I can 
picture on paper, of the potassium carbonate (K 2 C0 3 ) contains, I 
am told, two atoms of potassium (K 2 ), and a molecule of the hydrate 
(KHO) one atom (K). Therefore — therefore — each molecule of the 
carbonate (K 2 C0 3 ) will furnish two molecules of the hydrate (2KHO). 
Moreover, I notice that in the formula of a molecule of the calcium 
hydrate (slaked lime) I employ there are 2 of the HO (that is, 2HO) ; 
and this fact confirms me in the deduction that one molecule of the 
carbonate affords two molecules of the hydrate." The pupil will 



then amend his diagram thus : 




2KHO 



Ca2HO 



Fourthly, the question as to what becomes of the other elements 
must be cleared up. Indeed, when the reader remembers that he is 
studying this reaction for the aid it affords him in learning Chem- 
istry, and not because he is desirous of manufacturing caustic pot- 
ash, he will see that this latter part of the reaction is quite as 
important as the former. To complete the diagram, then, he must 
first know what other compound is produced, and its formula. The 
context of his Manual will afford this information. In this case cal- 
cium carbonate is produced (CaC0 3 ). (This product is, in fact, pre- 



POTASSIUM. 



65 



cipitated chalk, together with any excess of slaked lime and any 
natural impurities in the slaked lime. Pure " precipitated chalk" 
is made by an analogous reaction, described subsequently.) The 
source of the elements of the calcium carbonate, and, finally, their 
union, must be indicated just as the source and mode of formation 
of the potash were indicated ; that is to say, after the formula of 
this second substance produced (CaC0 3 ) is written on the right hand 
of the diagram, thus — 

2KHO 



CaCO, 




Ca2HO 



the source of its elements is shown by writing the symbols for those 
elements on the right of the bracket attached to the formula con- 
taining the symbols of the elements, thus : 

2KHO 



CaCO, 




Ca2H0{ 2 c f 



Lines converging from the symbols of these elements also, and unit- 
ing at the formula of the substance (CaC0 3 ), are then drawn to sug- 
gest approach of the atoms of the elements and their union to form 
a molecule of the compound. The diagram will now be complete, 
and will have been built up in the student's note-book thus : 

2KHO 



K 2 C0 3 1 h 



Ca2HO 



(2HO 
|Ca 




CaCO, 



The formation of a third product or a fourth product would be 
indicated in a similar manner. 

Note 1. — It will be seen that the chief data required in making 
either equationary or diagrammatic notes of decompositions are the 
symbolic formulae of the various compounds employed and produced. 
These formulae are, 'in this Manual, given whenever necessary. 
Chemists obtain them in the first instance by help of quantitative 
analysis. By the latter means also is obtained a check on the prob- 
abilities respecting the relative number of molecules concerned in a 
reaction. 

Note 2. — While an equation or a diagram is an attempt to picture 
the reaction which ensues when molecules of different substances 



66 THE METALLIC RADICALS. 

act upon one another, it necessarily only represents two or a min- 
imum number of the molecules. The student will of course under- 
stand that what is true of these two or three molecules is true of 
the thousands or millions of molecules forming the mass or whole 
quantity of material on which he experiments. 

Note on Nomenclature. — Hydrates are bodies indirectly or 
directly derived from water by one-half of its hydrogen becom- 
ing displaced by an equivalent quantity of another radical. 
Thus, a piece of potassium thrown on to water (HHO) instantly 
liberates hydrogen, potassium hydrate (KHO) being formed. 
The temperature produced at the same time is sufficiently high 
to cause ignition of the hydrogen, which burns with a purple 
flame (owing to the presence of a little vapor of potassium), 
while the potassium hydrate remains dissolved in the bulk of 
the water. This radical, or root, or group of elements (HO), 
common to all hydrates, is called hydroxyl. Water might be 
termed hydrogen hydrate, or hydrogen hydroxylide, or hydro- 
gen hydroxide. 

Explanation. — With regard to the group of atoms repre- 
sented by the symbols C0 3 and HO only a few words need be 
said here. The former (C0 8 ) is the grouping (root or radical) 
found in all the molecules of all carbonates ; it is termed the 
carbonic radical, and is as characteristic of the molecules of 
carbonates as potassium (K) is of the molecules of potassium 
salts. HO (hydroxyl) is characteristic of all molecules of all 
hydrates. C0 3 is a bivalent root, HO is univalent ; hence the 
group of atoms represented by C0 3 is found united with two 
univalent atoms, as in potassium carbonate, K 2 C0 3 , or with one 
bivalent atom, as in calcium carbonate, CaC0 3 ; and HO is 
found united in single proportion with univalent atoms, as in a 
molecule of potassium hydrate, KHO, or in double proportion 
with bivalent atoms, as in a molecule of calcium hydrate, 
Ca2HO. The quantivalence of a metal has only to be learnt, 
and the formulae of its carbonate and hydrate are ascertained 
without seeing the formula of either ; and this principle applies 
to formulas of all other metallic salts. But, beyond commit- 
ting to memory the formulas and quantivalence of the various 
groupings characteristic of carbonates, hydrates, nitrates, sul- 
phates, acetates, etc. (see the following table), special attention 
should not at present be devoted to the subject of the consti- 
tution of salts, but restricted to what may be called the metal- 
lic or basylous side of salts. The formulae and quantivalence 
of the chief acidulous groupings referred to, and the symbols 
and quantivalence of allied elementary bodies, are included in 
the following table : 



POTASSIUM. 



67 



Formulae and Quantivalence of Acidulous Radicals. 

All chlorides contain CI 

Br 

I 

CN 

HO 

N0 3 

CIO, 



it 


bromides 


u 


it 


iodides 


a 


a 
it 
u 


cyanides 
hydrates 
nitrates 


u 
a 

a 


a 


chlorates 


it 


a 


acetates 


a 


a 


oxides 


it 


a 
a 
it 
it 


sulphides 
sulphites 
sulphates 
carbonates 


ti 

a 
a 

it 


a 


oxalates 


a 


a 


tartrates 


it 


it 


citrates 


(t 


it 

a 


phosphates 
borates 


it 

a 






C 2 H 3 2 


s 

so 3 
so 4 
co 3 

CA 

C 4 H 4 0«J 
C 6 H 5 7 
P0 4 
BO, 






P-. < 

p 



\ p a> 



Radicals. — The above elements and compounds are termed 
radicals, each being the common root (radix) in a series of 
salts. Why compound radicals (as N0 3 , S0 4 , P0 4 , etc.) differ 
in quantivalence need not be fully explained at present. Their 
constituent atoms doubtless always exert the same amount of 
attractive force, nearly but not quite all this force being ex- 
erted in retaining the atoms in one group, and the remainder 
probably determining the quantivalence. Compound radicals 
are more or less stable groups of atoms, capable of migration 
without change, but not necessarity capable of existing in the 
free state.* 

Liquor Potassse. 

Liquor Potassse, B. P., is officially directed to be made as 
follows : f 



* Some modern chemical authors term these roots radicles, a word more 
usefully expressive of little roots or rootlets. The word radicle is iudeed 
thus used as a diminutive in botany. 

f The official processes will not usually be reprinted in this Manual, 
belonging, as they do, more to the manufacturing than to the educational 
side of practical chemistry. But pupils should take care that they 
understand every word of the processes, whether as regards chemical or 
mechanical details: the medical student in order that he may learn 
chemical principles — the principles on which the successful practice of 
modern medicine depends ; the pharmaceutical student in order that he 
too may know the principles on which his avocation largely depends, and 



68 THE METALLIC RADICALS. 

Dissolve 1 pound of carbonate of potassium in 1 gallon of 
water ; heat the solution to the boiling-point in a clean iron 
vessel, gradually mix with it 12 ounces of washed slaked lime 
(obtained from about 13 ounces of slaked lime washed with 
distilled water until a little of the washings, acidified with 
nitric acid, gives no cloudiness with nitrate of silver), and con- 
tinue the ebullition for ten minutes with constant stirring. Then 
remove the vessel from the fire, and when, by the subsidence 
of the insoluble matter, the supernatant liquor has become 
perfectly clear, transfer it by means of a siphon or by decanta- 
tion to a green-glass bottle furnished with an air-tight stopper, 
and add distilled water, if necessary, to make it correspond 
with the tests of specific gravity and neutralizing power. (These 
tests and the modes of applying them will be explained in sub- 
sequent sections.) 

Liquor Potassse, U. S. P., is prepared in a very similar way, 
starting with the bicarbonate, which by ebullition resolves itself 
into potassium carbonate, water, and carbonic acid gas : 
2KHC0 3 = K 2 C0 3 + H 2 +C0 2 . 

Potassa cum Calce, U. S. P., is a grayish-white powder, made 
by rubbing together equal weights of solid potash and quick- 
lime. 

Solid Potash. — Solution of potash evaporated to dryness in a 
silver or clean iron vessel, and the residue fused and poured into 
moulds, constitutes Potassa, U. S. P. It often contains chlorides, 
detected by silver nitrate, and sulphates, detected by a barium salt, 
as described subsequently in connection with hydrochloric and sul- 
phuric acids. 

Sulphurated Potash. 

Synonyms. — Sulphurated Potassa ; Liver of Sulphur ; Impure 
Potassium Sulphide. 

Second Synthetical Reaction. — Into a test-tube put a few 
grains of a mixture of previously dried potassium carbonate 
with half its weight of sulphur. Heat the mixture gradually 
until it ceases to effervesce. The resulting fused mass, poured 
on a slab and quickly bottled, is the Potassa Sidphurata, sul- 
phurated potash, of the United States Pharmacopoeia. 

3K 2 C0 3 + 4S 2 = K 2 S 2 3 + 2K 2 S 3 + 3C0 2 

Potassium Sulphur. Potassium Potassium Carbonic 

carbonate. hyposulphite. sulphide. acid gas. 

in order that he may apply those principles in his pursuit of that avoca- 
tion. With such views before him each student should carefully read 
through the above process, and in future, after making an officially 
interesting synthetical experiment, should turn to the corresponding 
monograph in his pharmacopoeia and assure himself that he understands 
all that is there stated. 



POTASSIUM. 



69 



As met with in pharmacy, this salt is not a single definite chem- 
ical compound, but a mixture of several ; in short, its chemical 
character is well indicated by its vague name. When fresh, and if 
carefully prepared with the official proportions of dry ingredients, it 
is of the color of liver (whence the old name " liver of sulphur"), 
and consists, as shown by J. Watts, of the salts mentioned in the 
foregoing equation, together with a little undecomposed potassium 
carbonate, with perhaps higher sulphides of potassium (K 2 S 4 and 
K 2 S 5 ) ; but, rapidly absorbing oxygen from the air, it soon be- 
comes green, and yellow potassium sulphite (K 2 S0 3 ) and sulphate 
(K 2 S 7 4 ) are successively formed, and ultimately a useless mass of 
a dirty-white color results, consisting of sulphate and hyposulphite, 
with generally some potassium carbonate and free sulphur. More- 
over, if overheated in manufacture, the hyposulphite 4(K 2 S 2 3 ) is 
decomposed into potassium sulphate 3(K 2 S 7 4 ) and sulphide (K 2 S 5 ). 
Recently made, about 50 per cent, should be soluble in rectified 
spirit. It is occasionally employed in the form of ointment (Un- 
guentum Potassce Sulphurated, B. P.). 

" On triturating 1 grm. of sulphurated potash with 1 grin, of crys- 
tallized copper sulphate and 10 cc. of water, and filtering, the fil- 
trate should remain unaffected by hydrogen sulphide, corresponding 
to at least 12.85 per cent, of sulphur combined with potassium to 
form sulphide."— U. S. P. 

The extremely — indeed, most unusually — complicated nature of 
the decomposition will probably cause failure in any attempt by a 
student to draw out an equation or a diagram of the reaction with- 
out the aid of the printed equation given above. He may therefore 
content himself in this case by introducing into his note-book a 
diagram founded directly on the equation and on the numbers of 
molecules there stated. With this printed equation, and the details 
of construction of diagrams given in connection with the first syn- 



Fig. 12. 



Fig. 13, 



Fig. 14. 




Crucibles of Various Forms. 

thetical reaction, he will be able to give a diagram of this second 
synthetical reaction without unduly troubling his reasoning powers, 
while at the same time he will be familiarizing himself with the 
more mechanical portions of the diagram. 

In preparing large quantities of sulphurated potash the test- 
tube is replaced by an earthenware vessel termed a crucible 

4* 



70 THE METALLIC RADICALS. 

(possibly from crux, a cross, for originally a cross was impressed 
upon the melting-pot as used by alchemists and goldsmiths : 
others derive the word from crux, an instrument of torture, the 
sense here being symbolical). 

Heating Crucibles. — Crucibles of a few ounces' capacity may be 
heated in an ordinary grate-fire. Larger ones require a stove with 
a good draught — that is, a furnace. Even the smaller ones are 
more conveniently and quickly heated in a furnace. Half-ounce or 
one-ounce experimental porcelain crucibles may be heated in a 
spirit or gas ilame, the air-gas flame already described being gener- 
ally the most suitable. 

Potassium Acetate. 

Synonyms. — Acetate of Potassium 5 Acetate of Potash. 

Third Synthetical Reaction. — Place 10, 20, or more grains of 
potassium carbonate in a small dish, and saturate (satur, full) 
with acetic acid ; that is, add acetic acid so long as effervescence 
is thereby produced ; the resulting liquid is a strong, slightly 
acid solution of potassium acetate. Evaporate most of the 
water in an open dish (see Figs. 15 and 16, p. 71), stirring with 
a glass rod * to promote evolution of vapor ; a white salt re- 
mains, which fuses on the further careful application of heat : 
this is the official potassium acetate (Potassii Acetas, U. S. P.), 
formerly termed acetate of potash. If fused in the open vessel, 
the acetate is liable to become slightly charred and discolored; 
this is prevented by transferring the solid residue to a test-tube 
or Florence flask before finally fusing. It forms a white deli- 
quescent, foliaceous, satiny mass, neutral to test-paper and 
wholly soluble in spirit. A 10 per cent, solution in water forms 
the " Solution of Acetate of Potassium," B. P. 

K 2 C0 3 + 2HC 2 H S 2 = 2KC 2 H 3 2 + H 2 + C0 2 

Potassium Acetic Potassium Water. Carbonic 

carbonate. acid. acetate. acid gas. 

Explanation of Formulas. — The formula for one molecule of acetic 
acid (hydrogen acetate) is HC 2 H 3 2 , and one of potassium acetate 
KC 2 H 3 2 . The grouping, C 2 H 3 2 , is characteristic of all acetates ; it 
is univalent. 

Explanation of Process. — When two molecules of acetic acid 
(2HC 2 H 3 2 ) and one of potassium carbonate (K 2 C0 3 ) react, two 
molecules of potassium acetate (2KC 2 H 3 2 ) and one of carbonic 
acid (H 2 C0 3 ) are produced, the latter at once splitting up into water 
(H 2 0) and carbonic acid gas (C0 2 ), as already shown in the equation. 

* Glass rod is usually purchased in the form of long sticks. The 
pieces may be cut to convenient lengths of from six" to twelve inches 
{vide p. 16), sharp ends being rounded off by holding the extremity in a 
flame for a few minutes. 



POTASSIUM. 



71 



Diagram of the Reaction. — The nature of the above operation is 
indicated by an equation ; it (and succeeding reactions) should be 
expressed in the student's note-book as a diagram, and, if possible, 
without the aid of the above equation. 

Note. — The foregoing reaction has a general as well as a special 
synthetical interest. It represents one of the commonest methods of 
forming salts — namely, the saturation of a carbonate by an acid, or 
vice versa ; carbonates added to acetic acid yield acetates, to nitric 
acid nitrates, to sulphuric acid sulphates. Many illustrations of 
this general process occur in pharmacy. 

Evaporation of water from a liquid is best conducted in wide 
shallow vessels rather than in narrow deep ones, as the steam can 
thus quickly diffuse into the air and be conveyed rapidly away • 
hence a small round-bottomed basin, heated as shown in Fig. 15, is 
far more suitable than a test-tube for such operations. On the 
manufacturing scale iron or iron lined with enamel or semi-por- 
celain, copper, tinned copper, or solid tinned pans are used. Up to 
twelve or eighteen inches diameter, pans, basins, or dishes made 
of Wedgwood ware or porcelain composition (Fig. 16) may be 
employed. Small dishes may be supported by retort stands (Fig. 
15), larger by cylinders (Fig. 16), to which the dish is, if less in 
diameter than the cylinder, adapted by such flat rings or diaphragms 
as are shown in the figure. 

Fig. 15. Fig. 16. 





Evaporation from Small and Large Basins. 

Potassium Bicarbonate. 

Synonyms. — Bicarbonate of Potassium ; Bicarbonate of Potash. 

Fourth Synthetical Reaction. — Make a strong solution of 
potassium carbonate by heating in a test-tube a mixture of sev- 
eral grains of the salt with rather less than an equal weight of 
water. Through the cool solution pass carbonic acid gas slowly 
but continuously ; after a time a white crystalline precipitate 
of potassium acid carbonate or bicarbonate (KHC0 3 ) of the 
Pharmacopoeia (Potassii Bicarbonas, U. S. P.) will be formed. 
K 2 C0 3 + H 2 + C0 2 = 2KHC0 3 

Potassium AVater. Carbonic Potassium 

carbonate. acid gas. bicarbonate. 



72 THE METALLIC RADICALS. 

The carbonic acid gas for this operation is economically and con- 
veniently prepared from small lumps of marble, though it might be 
obtained from any carbonate ; thus the previous synthetical reaction 
could be made available for this purpose, the carbonic acid gas 
evolved on the addition of the acetic acid to the potassium carbonate 
being conducted into a strong solution of more potassium carbonate 
by a glass tube bent and fitted as described when treating of oxygen 
gas. Economy also causes hydrochloric acid to be used in prefer- 
ence to acetic or any other acid. 

Generate the carbonic acid gas by adding common hydro- 
chloric acid, diluted with twice its bulk of water, to a few 
fragments of marble contained in a test-tube or small flask, 
and conduct the gas into the solution of potassium carbonate 
by a glass tube bent to a convenient angle or angles and fitted 
to the test-tube by a cork in the usual way (see Fig. 10, p. 28, 
though no heat is necessary). The tube may be replenished 
with marble or acid, or both, when the evolution of gas is 
becoming slow. In working on any larger quantity than a few 
grains of the carbonate a wide delivery-tube should be employed, 
or the end of the narrow tube occasionally be cleared from any 
bicarbonate that may have been deposited in it. A more econom- 
ical arrangement of the apparatus employed in this process will 
be described under the corresponding sodium salt (p. 88). 

Deposition of the Bicarbonate explained. — Potassium bicarbonate 
is to a certain extent soluble in water, but as it is less so than the 
potassium carbonate, and as a saturated solution of the latter has 
been used, a precipitation of a part of the bicarbonate inevitably 
occurs. In other words, the quantity of water present is sufficient 
to keep the carbonate, but insufficient to retain the equivalent quan- 
tity of bicarbonate, in solution. 

Properties. — Prepared on the large scale, potassium bicarbonate 
occurs in colorless, non-deliquescent right rhombic prisms ; it has 
a saline, feebly alkaline, non-corrosive taste. Heated to redness, it 
loses 31 per cent, of its weight, and is converted into carbonate 
(K 2 C0 3 ), water (H 2 0), and carbonic acid gas (C0 2 ). 

+ H 2 + CO, 

2)200 

100 = 

The foregoing equation and accompanying molecular weights (see 
page 55) show how potassium bicarbonate, the molecular weight of 
which happens to be 100, must lose 31 per cent. (9 + 22) when com- 
pletely decomposed by heat. 

Effervescing Solution of Potash. — A solution of 30 grains of this 
bicarbonate in 1 pint of water, charged with five times its bulk of 
carbonic acid gas by pressure, is medicinal u potash-water," Liquor 
Potasso? Effervescens, B. P. 




POTASSIUM. 73 

Notes on Nomenclature. — The prefix hi- in the name " potassium 
bicarbonate'' serves to recall the fact that to a given amount of 
potassium this salt contains twice as much carbonic radical as the 
carbonate. The salt is really " potassium and hydrogen carbonate " 
(KHCOg) 5 it is intermediate between potassium carbonate (K 2 C0 3 ) 
and hydrogen carbonate or true carbonic acid (H 2 C0 3 ) ; it is " acid 
potassium carbonate" or "hydrogen potassium carbonate." Hence 
in constitution it is an acid salt, although not acid to the taste. 

Salts whose specific names end in the syllable " ate" (carbonate, 
sulphate, etc.) are in general conventionally so termed when they 
contain the radical, or the characteristic elements, of an acid whose 
name ends in " ic," and from which acid they have been or may be 
formed. Thus the syllable " ate 1 ' in the words sulphate, nitrate, 
acetate, carbonate, etc. indicates that the respective salts contain the 
radical of an acid whose name ends in ic, the previous syllables, 
sulph-, nitr-, acet-, carbon-, indicating what that acid is — sulphuric, 
nitric, acetic, or carbonic. Occasionally a letter or syllable is 
dropped from or added to a word to render the name more eupho- 
nious 5 thus the sulphuric radical forms sulphates, not sulphurates, 
and the tartaric radical yields tartrates, not tartarates. 

Potassium Citrate. 

Synonyms — Citrate of Potassium ; Citrate of Potash. 

Fifth Synthetical Reaction. — Dissolve a few grains or more 
of potassium bicarbonate in water, and add citric acid (H 3 C 6 H 5 7 ) 
until it no longer causes effervescence. The resulting liquid is 
a solution of potassium citrate (K 3 C 6 H 5 7 ). Evaporate to dry- 
ness in an open dish cautiously, so as to avoid charring ; a pul- 
verulent or granular residue is obtained, which is the official 
Potassii Citras (U. S. P.), a white deliquescent powder. 

3KHC0 3 -f H 3 C 6 H 5 7 = K 3 C 6 H 5 7 + 3H 2 + 3C0 2 . 

Potassium Citric acid. Potassium Water. Carbonic 

bicarbonate. citrate. acid gas. 

Citrates. — The citric radical or group of elements, which with 
three atoms of hydrogen forms a molecule of citric acid, and with 
three of potassium, potassium citrate, is a trivalent grouping ; 
hence the three atoms of potassium in a molecule of the citrate. 
The full chemistry of citric acid and other citrates will be described 
subsequently. 

Potassium Nitrate. 

Synonyms. — Nitrate of Potassium; Nitrate of Potash-, Nitre. 

Potassium Nitrate (KN0 3 ) (Potassii Nitras, U. S. P.), the old 
nitrate of potash, and 

Potassium Sulphate. 

Synonyms. — Sulphate of Potassium ; Sulphate of Potash. 
Potassium Sulphate (K 2 S0 4 ), (Potassii Sulphas, U. S. P.), could 



74 THE METALLIC RADICALS. 

obviously also be made by saturating nitric acid (HN(X) and sulphuric 
acid (H 2 S0 4 ), respectively, with potassium carbonate. Practically, they 
are not made in that way— the nitrate occurring, as already stated, 
in nature, and the sulphate as a by-product in many operations. 
Both salts will be alluded to hereafter in connection with nitric acid. 

Potassium Tartrate. 

Synonyms. — Tartrate of Potassium ; Tartrate of Potash. 

Sixth Synthetical Reaction. — Place a few grains of potassium 
carbonate in a test-tube with a little water, heat to the boiling- 
point, and then add acid potassium tartrate (KHC 4 H 4 6 ) till 
there is no more effervescence ; a solution of neutral potassium 
tartrate (KKC^Oe) results, the Potassii Tartras of the United 
States Pharmacopoeia, the old tartrate of potash or " soluble 
tartar." Crystals (four- or six-sided prisms) may be obtained 
on concentrating the solution by evaporation and setting the 
hot liquid aside. Larger quantities are made in the same way, 
20 of acid tartrate and 9 of carbonate (with 50 of water) being 
about the proportions necessary for neutrality. 

2KHC 4 H 4 6 -f K 2 C0 3 - 2K 2 C 4 H 4 6 + H 2 + C0 2 

Acid potassium Potassium Neutral potassium Water. Carbonic 

tartrate. carbonate. tartrate. acid gas. 

Tartrates. — C 4 H 4 6 are the elements characteristic of all tartrates : 
they form a bivalent grouping ; hence the formula of the hydrogen 
tartrate, or tartaric acid, is H 2 C 4 H 4 6 •, that of the potassium tar- 
trate, K 2 C 4 H 4 6 ; of the intermediate salt, the acid potassium tartrate 
(cream of tartar), KHC 4 H 4 6 . If the acid tartrate of one .metal and 
the carbonate of another react, a neutral dimetallic tartrate results, 
as seen in Rochelle salt (KNaC 4 H 4 O e ), the Soda Tartarata of the 
British Pharmacopoeia {Potassii et Sodii Tartras, U. S. P.). 

Acid Salts (e. g. KHC 4 H 4 6 ) — that is, salts intermediate in com- 
position between a neutral salt (e. g. K 2 C 4 H 4 6 ) and an acid (e. g. 
H 2 C 4 H 4 6 ) — will frequently be met with. All acidulous radicals, 
except those which are univalent, may be concerned in the forma- 
tion of such acid salts. 

Potassium Iodide, or Iodide of Potassium. 

Seventh Synthetical Reaction. — Into solution of potash, heated 
in a test-tube, flask, or evaporating basin according to quantity, 
stir a little solid iodine. The deep color of the iodine disap- 
pears entirely. This is due to the formation of the colorless 
salts, potassium iodide (KI) and potassium iodate (KI0 3 ), 
which remain dissolved in the liquid. Continue the addition of 
iodine so long as its color, after a few minutes' warming and 
stirring, disappears. When the whole of the potash in the 
solution of potash has been converted into the salts mentioned, 



POTASSIUM. 75 

the slight excess of iodine remaining in the liquid will color it, 
and thus show that this stage of the operation is completed. 



6KHO 


+ 31, . 


= 5KI -f- KI0 3 + 


3H 2 


Potassium 


Iodine. 


Potassium Potassium 


Water. 


hydrate. 




iodide. iodate. 





Separation of the Iodide from, the Iodate. — Evaporate the 
solution to dryness. If each salt were required, the resulting 
mixture might be digested in spirit of wine, which dissolves 
the iodide, but not the iodate. But the iodide only is needed. 
Intimately mix the residue, therefore (reserving a grain or two 
for a subsequent experiment), with excess (about a third of its 
weight) of charcoal, and gently heat in a test-tube or crucible 
until slight deflagration ensues* The crucible may be held in 
a spirit or air-gas flame or other fire by tongs. (Scissors-shaped 
and other " crucible-tongs " are sold by all makers of appara- 
tus.) The iodide remains unaffected, but the iodate loses all 
its oxygen, and is thus also reduced to the state of iodide. 

2KI0 3 + 3C 2 = 2KI + 6CO 

Potassium Carbon. Potassium Carbonic 

iodate. iodide. oxide. 

Treat the mass with a little water, and filter to separate 
excess of charcoal ; a solution of pure potassium iodide results 
(Potassii lodidum, U. S. P.). The latter may be used as a 
reagent or it may be evaporated to a small bulk and set aside 
to crystallize. 

Properties. — Potassium iodide crystallizes in small cubical crys- 
tals, very soluble in water, less so in spirit. One part in twenty of 
water forms " Solution of Iodide of Potassium," U. S. P. Exposed 
to air and sunlight, pure potassium iodide becomes slightly brown, 
owing to the liberation of iodine. Under these circumstances a lit- 
tle potassium carbonate is produced by action of the atmospheric 
carbonic acid, hydriodic acid (HI) is set free, and the latter, attacked 
by oxygen, yields a trace of water and of free iodine. 

The addition of charcoal in the above process is simply to facili- 
tate the removal of the oxygen* of the potassium iodate. Potassium 
iodate (KI0 3 ) is analogous in constitution and in composition, so far 
as the atoms of oxygen are concerned, to potassium chlorate 

* If, in the operation of heating potassium iodate with charcoal, excess 
of the latter be employed, slight incandescence rather than deflagration 
occurs; if the charcoal be largely in excess, the reduction of the 
potassium iodate to iodide is effected without visible deflagration or even 
incandescence. 

Deflagration means violent burning, from flagratus, burnt (flagro, to 
burn), and de, a prefix augmenting the sense of the word to which it 
may be attached. Paper thrown into a fire simply burns, nitre deflag- 
rates. Detonate (detono) is a precisely similar word, meaning to explode 
with violent noise. 



76 THE METALLIC RADICALS. 

(KClOg), which has already been stated to be more useful than any- 
other salt for the actual preparation of oxygen gas itself. Hence 
the removal of the oxygen of the iodate might be accomplished by 
heating the residue without charcoal. In that case the liberated 
oxygen would be detected on inserting the incandescent extremity 
of a strip of wood into the mouth of the test-tube in which the mix- 
ture of iodide and iodate had been heated. The charcoal, however, 
burns out the oxygen more quickly, and thus economizes both heat 
and time. 

Note. — The formula of potassium iodide (KI) shows that the salt 
contains potassium and iodine in atomic proportions. A reference 
to the table of Atomic Weights at the end of the volume and a rule- 
of-three sum would therefore show what weight of salt is producible 
from any given weight of iodine. 

Detection of Potassium Iodate in Potassium Iodide. — Potas- 
sium iodate remaining as an impurity in potassium iodide may 
be detected by adding to a solution of the latter salt some weak 
acid (say, tartaric), shaking, and then adding starch mucilage ; 
blue " starch iodide " is formed if a trace of iodate be present, 
but not otherwise. By the reaction of the added acid and the 
potassium iodate iodic acid (HIO s ) is produced ; and by 
reaction of the added acid and the potassium iodide hydriodic 
acid (HI) is produced ; neither of these alone attacks starch, 
but by reaction on each other they give free iodine, which 
then forms the blue color. This experiment should be tried on 
a grain or two of pure iodide and on the impure iodide reserved 
from the previous experiment. Potassium iodide containing 
iodate would obviously yield free iodine, which is excessively 
corrosive, on the salts coming into contact with the acids of 
the stomach. 

HIO3 + 5HI - 3H 2 + 3I 2 . 

Note on Nomenclature. — The syllable ide attached to the syllable 
iod in the name "potassium iodide" indicates that the element 
iodine is combined with the potassium. An iodate, as already 
explained, is a salt containing the characteristic elements of iodic 
acid and of all iodic compounds. Inorganic salts, one of whose 
names ends in ide, are those which are, or may be, formed from 
elements. The names of salts which are, or may be, formed from 
compounds include other syllables, ate being one (see page 73). 
The only other syllable is ite, which is included in the names of 
salts which are, or may be, formed from the acids and radicals whose 
names end in ous : thus sodium sulphzfe, etc. To recapitulate : An 
inorganic salt whose name ends in ate contains a compound acidulous 
radical whose name ends in ic ; a salt whose name ends in ite con- 
tains a compound acidulous radical whose name ends in ous ; an 
inorganic salt whose name ends in ide contains an element for its 
acidulous radical. Thus sulph^e relates to sulphur, sulpha to the 



POTASSIUM. 77 

sulphurous radical, sulphate to the sulphuric radical, and so on 
with other inorganic " ides," "ites," or " ates." 

Potassium Bromide, or Bromide of Potassium. 

Potassium Bromide (Potassii Bromidum, U. S. P.). — This salt is 
identical in constitution with potassium iodide, and is made in 
exactly the same way, bromine being substituted for iodine. The 
formula of bromic acid is HBr0 3 . It will be noticed that the fol- 
lowing equations are similar in character to those showing the prep- 
aration of potassium iodide : 



6KHO + 3Br 2 = 5KBr + KBr0 3 


+ 3H 2 


'otassiuru Bromine. Potassium Potassium 
hydrate. bromide. bromate. 


Water. 


2KBr0 3 + 3C 2 = 2KBr + 


6CO 


Potassium Carbon. Potassium 
bromate. bromide. 


Carbonic 
oxide. 



Potassium Manganates, or Manganates of Potassium. 

Eighth Synthetical Reaction. — Place a fragment of solid 
caustic potash (KHO), with about the same quantity of potas- 
sium chlorate (KC10 3 ) and of black manganese oxide (Mn0 2 ), 
on a piece of platinum -foil* Hold the foil by a small pair of 
forceps or tongs in the name of a blowpipe for a few minutes 
until the fused mixture has become dark green, apparently 
black. This color is that of potassium manganate (K 2 Mn0 4 ). 

6KHO + KCIO3 + 3Mn0 2 = 3K 2 Mn0 4 + KC1 + 3H 2 

Potassium Potassium Black manga- Potassium Potassium Water, 

hydrate. chlorate. nese oxide. manganate. chloride. 

Ninth Synthetical Reaction. — Potassium Permanganate 
(K 2 Mn 2 8 ) (Potassii Permanganas, U. S. P.), the old perman- 
ganate of potash, which is purple, is obtained, or rather a solu- 
tion of it, on placing the foil and its adherent mass in water 
and boiling for a short time. 



3K 2 Mn0 4 


+ 


2H 2 : 


= K 2 Mn 2 8 + 4KHO 


4- Mn0 2 


Potassium 




Water. 


Potassium Potassium 


Black manga- 


manganate. 






permanganate. hydrate. 


nese oxide. 



On the large scale the potash set free in the reaction is neutral- 
ized by sulphuric or, better, carbonic acid, and the solution evapo- 
rated to the crystallizing point. Further details will be given in 
connection with Manganese. 

* The foil may be one inch broad by two inches long. No ordinary 
flame will melt the platinum, fused caustic alkalies only slowly corrode 
it, and very few other chemical substances affect it at all ; hence the 
same piece may be used in experiments over and over again. Most 
metals form a fusible alloy with platinum, and phosphorus rapidly 
attacks it ; hence such substances, as well as mixtures likely to yield 
them, should be heated in a small porcelain crucible. 



78 THE METALLIC KADICALS. 

Solutions of (green) potassium and sodium manganates (or pur- 
ple) permanganates so readily yield their oxygen to organic matter 
that they are used on the large scale as disinfectants. 

Synthetical Reactions, bringing under consideration the remain- 
ing official compounds (namely, potassium bichromate, arsenite, 
chlorate, cyanide, ferrocyanide, and ferricyanide) are deferred at 
present. 

Crystallization. — This operation will have been performed several 
times in the course of the foregoing synthetical experiments. 
Obviously it offers a mode of separating soluble crystallizable sub- 
stances from soluble amorphous {a, without ; fioptjyq, morphe, shape) 
substances ; also of separating from each other substances of vary- 
ing degrees of solubility or which crystallize with varying degrees 
of readiness— fractional crystallization. 

(6) Reactions having Analytical Interest (Tests'). 

Note. — These are reactions utilized in searching for small quan- 
tities of a substance (in the present instance potassium) in a solu- 
tion. They are best performed in test-tubes or other small vessels. 
Each reaction should be expressed in the form of an equation or 
diagram in the student's note book. All previous or future equa- 
tions given in this volume should be transferred to the note-book in 
the form of diagrams, constructed as described on pages 63 to 66, 
unless the student can with ease construct equations without the 
aid of the Manual. 

First Analytical Reaction* — To a solution of any potassium 
salt (chloride,f for example) add a few drops of hydrochloric 
acid and of a solution of platinum perchloride % (PtCl 4 ), and 

* As already indicated, chemical reactions are scarcely analytical or 
synthetical in themselves, but rather performed with an analytical or 
synthetical object. Indeed, not infrequently one and the same reaction 
is both a synthetical and an analytical reaction. Thus this first so- 
called "analytical reaction" is a synthetical reaction if performed with 
the object of preparing a specimen of the double platinum and potassium 
chloride. It is an analytical reaction, or rather has analytical interest, 
if performed with the object of demonstrating the presence of potassium. 
Chemical reactions in themselves are operations not so much of analysis 
(resolution) or synthesis (combination), or of analysis and synthesis 
conjoined, as of what has sometimes been termed metathesis (transposi- 
tion). Molecules are not torn to atoms in an operation performed with 
an analytical object, nor are the atoms put together or set together in 
an operation (perhaps the same operation) performed with a synthetical 
object; but in both operations the atoms of the molecules undergo 
metathesis; that is, exchange places or are transposed. In short, 
chemists use the words " analytical " and "synthetical" in a conven- 
tional rather than a strictly etymological sense. 

f A few fragments of potassium carbonate, two or three drops of 
hydrochloric acid, and a small quantitv of water give a solution of 
potassium chloride at once, K2CO3 + 2HC1 = 2KC1 + H 2 ■+■ C0 2 . 

% Experiments with such expensive reagents as platinum perchloride 
are economically performed in watch-glasses, drops of the liquids being 
operated on. 



POTASSIUM. 79 

stir the mixture with a glass rod ; a yellow granular or slightly 
crystalline. precipitate* slowly forms. (This precipitate is the 
double platinum and potassium chloride, and its composition is 
expressed by the formula PtCl 4 ,2KCl.) 

Memoranda. — When the precipitate is long in forming, it is some- 
times of an orange-yellow tint. If potassium iodide happens to be in 
the potassium salt under examination, some platinum iodide (Ptl 4 ) 
will also be formed, giving a red color to the solution, and a larger 
quantity of the precipitant (that is, the precipitating agent) will be 
required. 

Precaution. — Only potassium chloride forms this characteristic 
compound ; hence if the potassium salt in the solution is known 
not to be a chloride, or if its composition is unknown, a few drops 
of hydrochloric acid must be added, otherwise some of the platinum 
perchloride will be utilized for its chlorine only, the platinum being 
wasted. Thus, if potassium nitrate (KN0 3 ) be the salt present, a 
little hydrochloric acid enables the potassium to assume the form 
of chloride when the platinum perchloride is added, nitric acid 
(HN0 3 ) being set free. 

Explanations. — The precipitate is, practically, insoluble in water. 
It is for this reason that a very small quantity of any soluble potas- 
sium salt (or, rather, of the potassium in that salt) is thrown out of 
solution by platinum perchloride. 

Note on Nomenclature — When distinct molecules of salts unite 
and form a single crystalline compound, the product is often termed 
a double salt. The double potassium and platinum chloride is such 
a body. 

Educational Note. — The thoughtful student will not confuse the 
test with the chemistry of the test. The test itself appeals to the 
senses — commonly to the eye, sometimes to the nose, occasionally 
to the ear. A person may be able to apply a test, and yet never 
know anything of the chemistry of a test. 

Acid Potassium Tartrate. 

Synonyms. — Acid Tartrate of Potassium ; Acid Tartrate of Pot- 
ash ; Cream of Tartar. 

Second Analytical Reaction. — To a solution of any salt of 
potassium add excess of strong solution of tartaric acid 
(H 2 C 4 H 4 6 ), and shake or well stir the mixture ; a white granu- 
lar precipitate (acid potassium tartrate, KHCJH 4 6 ) will be 
formed. 

Note. — By " excess " of any test-liquid (such as the " solution of 
tartaric acid" just mentioned) is meant such a quantity as is prob- 
ably rather more than sufficient to convert the whole weight of the 

:; -By precipitation (from pr&cipitare, to throw down suddenly) is simply 
meant the formation of particles of solid in a liquid, no matter whether 
the solid, the precipitate, subsides or floats, and no matter whether the 
operation be entire and complete or partial and fractional. 



80 THE METALLIC RADICALS. 

compound attacked into the compound produced. Thus in the 
present case enough acid must be added to convert the whole of the 
potassium salt operated on into acid potassium tartrate. What the 
weight of salt operated on was must be mentally estimated, roughly, 
by the operator. It is not necessary in analyzing to know the 
exact weights of salts employed. The analyst must use his judg- 
ment, founded on his knowledge of the reaction (as shown by an 
equation) and of the molecular weights of the substances employed 
in the reaction, as well as by the rough estimate of the amount of 
material on which he is experimenting. 

Limits of the Tests. — Acid potassium tartrate is soluble in about 
180 parts of cold and in 6 parts of boiling water. Hence, in apply- 
ing the tartaric test for potassium the solutions must not be hot. 
Even if cold, no precipitate will be obtained if the solutions are very 
dilute. This test, therefore, is of far less value than that first men- 
tioned. The acid potassium tartrate is less soluble in diluted 
alcohol than in water, so that the addition of spirit of wine renders 
the reaction somewhat more delicate. 

Cream of Tartar. — The precipitate is the Potassii Bitartras, U. 
S. P., the old acid tartrate or bitartrate of potash or cream of tartar, 
though the official preparation is not formed in the above manner ; 
on the contrary, the acid is derived from the salt, which, often 
mixed with some calcium tartrate, occurs naturally in the juice of 
many plants. 

Third Analytical Reaction. — The flame-test. Dip the looped 
end of a platinum wire into a solution containing a potassium 
salt, and introduce the loop into the lower part of a spirit 
flame, the flame of a mixture of gas and air, a blowpipe flame, 
or other slightly colored flame. A light violet or lavender tint 
will be communicated to the flame, an effect highly character- 
istic of potassium salts. 

Fourth Analytical Fact. — Potassium salts are not readily 
volatile. Place a fragment of carbonate, nitrate, or other 
potassium salt on a piece of platinum -foil, and heat the latter 
in the flame of a lamp ; the salt may fuse to a transparent 
liquid and flow over the foil ; water also, if present, will escape 
as steam, and black carbon be set free if the salt happen to be a 
tartrate, citrate, etc. ; but the potassium compound itself will 
not be vaporized. This is a valuable negative property, as 
will be evident when the analytical reactions of ammonium 
come under notice. 

Other Tests. — Sodium cobaltic nitrite is an official test for 
potassium. 

QUESTIONS AND EXEECISES. 

Name the sources of potassium. — Give the source, formula, and cha- 
racters of potassium carbonate. — Distinguish between synthetical and 



SODIUM. 81 

analytical reactions. — How is the official Liquor Potassse prepared? — 
What is the systematic name of caustic potash? — State the chemical 
formula of caustic potash. — Construct an equation or diagram expressive 
of the reaction between potassium carbonate and slaked lime. — Define a 
hydrate. — What group of atoms is characteristic of all carbonates? — 
Define the term radical, — How is " sulphurated potash " made, and of 
what salts is it a mixture ? — What is the formula of the radical of all 
acetates? — Draw a diagram showing the formation of potassium acetate. 
— Give a process for the conversion of carbonates into other salts. — 
What is the difference between potassium carbonate and bicarbonate ? — 
How is the latter prepared ? — What is the relation between salts whose 
specific names end in the syllable "ate" and acids ending in "ic"? — 
Draw out diagrams or equations descriptive of the formation of potassium 
tartrate from the acid tartrate, and citrate from potassium carbonate. — 
Distinguish between a neutral and an acid salt. — How is potassium 
iodide made? — Illustrate the process either by diagrams or equations. — 
Work out a sum showing how much potassium iodide is producible from 
1000 grains of iodine. Ans. 1307 grains. — Give a method for the detec- 
tion of iodate in potassium iodide. — Explain the reaction. — Has the syl- 
lable " ide" any general signification in chemical nomenclature? — State 
the relations between sulphides, sulphites, and sulphates. — Mention the 
chemical relation of potassium bromide to iodide. — Describe the forma- 
tion of potassium permanganate, giving equations or diagrams. — How 
do manganates and permanganates act as disinfectants ?— Enumerate 
the tests for potassium, explaining by diagrams or equations the various 
reactions which occur. 

SODIUM. 

Symbol, Na. Atomic weight, 23. 

Formula, Na 2 . Probable molecular weight, 46. 

Memoranda. — Most of the sodium salts met with in pharmacy are 
obtained directly from sodium carbonate, which is now manufactured 
on an enormous scale from sodium chloride (common salt, sea-salt, 
bay-salt, or rock-salt), the natural source of the sodium salts. AVhen 
pure, salt (Sodii Chloridum, U. S. P.) occurs "in small white crys- 
talline grains or transparent cubic crystals, free from moisture ;" 
the best varieties commonly contain a little magnesium chloride and 
sometimes other impurities. Besides the direct and indirect use of 
sodium carbonate — or carbonate of soda, as it is commonly called — in 
medicine, it is largely used for household cleansing purposes under 
the name of "soda" and in the manufacture of soap. Sodium 
nitrate also occurs in nature, but is valuable for its nitric constit- 
uents rather than its sodium. Sodium is a constituent of about 
forty chemical or galenical preparations of the pharmacopoeias. 

Sodium (Sodium, B. P.) is prepared by a process similar to that 
for potassium, but with less difficulty. Castner obtains it compar- 
atively cheaply by distillation from a mixture of soda, carbon, and 
iron contained in steel vessels. It has a bright metallic lustre when 
freshly cut, but rapidly absorbs oxygen and carbonic acid gas from 
the air, and thus becomes coated with sodium carbonate. It dis- 
places hydrogen from water, yielding solution of sodium hydrate ; 
but unless the sodium is confined to one spot by placing it on a 
small floating piece of filter-paper, the action is not sufficiently 
intense to cause ignition of the escaping hydrogen. When the 



82 THE METALLIC BADICALS. 

latter does ignite, it burns with a yellow flame, due to the presence 
of a little vapor of sodium. 

Na 2 + 2H 2 = H 2 -f 2NaHO 

Sodium. Water. Hydrogen. Sodium hydrate. 

It similarly attacks alcohol, yielding "sodium ethylate" (see Index). 
It may be kept beneath the surface of a liquid containing neither 
moisture nor oxygen (mineral naphtha). It crystallizes" in octa- 
hedra. Its atom is univalent, Na'. 

Reactions having (a) Synthetical and (b) Analytical 
Interest. 

(a) Reactions having Synthetical Interest. 

Sodium Hydrate. 

Synonyms. — Sodium Hydroxide 5 Caustic Soda ; Hydrate of 
Sodium ; Hydrate of Soda : Soda. 

First Synthetical Reaction. — The formation of solution of 
sodium hydrate or caustic soda, NaHO {Liquor Sodse, U. S. P.), 
the old hydrate of soda, This operation resembles that of 
making solution of potash, already described. 



Na 2 C0 3 + 


Ca2HO = 


= 2NaHO 


+ CaC0 3 . 


Sodium 


Calcium 


Sodium 


Calcium 


carbonate. 


hydrate. 


hydrate. 


carbonate. 



The practical student should apply to this solution the remarks 
made concerning solution of potash. 

The official Liquor S00I02 is made from 170 grms. of crystals of 
sodium Carbonate, 50 of washed slaked lime, and 780 cc. of water, 
under precisely similar circumstances to those detailed for Liquor 
Pofassce (p. 63). If the solution be evaporated to dryness and the 
residue fused and poured into moulds, solid sodium hydrate (Soda, 
U. S. P.) is obtained. 

Commercial and cheap caustic soda is largely employed in various 
manufactures. This variety is a by-product in the manufacture of 
sodium carbonate, but, though highly useful as a chemical agent, is 
too impure for medicinal use. The United States Pharmacopoeia 
recognizes liquor sodas made from solid caustic soda about 56 parts 
and distilled water about 944, or from caustic soda of any other 
strength if only an equivalent amount be used and the product 
complies with the official tests. 

Second Synthetical Reaction. — The reaction of sulphur and 
sodium carbonate at a high temperature resembles that of 
sulphur and potassium carbonate, but as the product is not 
used in medicine, the experiment may be omitted. It is men- 
tioned here to draw attention to the close resemblance of the 
potassium salts to those of sodium. 



SODIUM. 



83 



Sodium Acetate, or Acetate of Sodium. 

Third Synthetical Reaction.— KM sodium carbonate (in pow- 
der, or, better, in fragments) to some strong acetic acid in an evap- 
orating basin as long as effervescence occurs, and then boil off 
some of the water * When the solution is cold, crystals of Ace- 
tate of Sodium, B. P., Sodii Acetas, U. S. P. (NaC 2 H 3 2 ,3H 2 0), 
the old acetate of soda, will be deposited. A 10 per cent, solution 
in distilled water forms the" Solution of Acetate of Sodium," B. P. 

Na 2 CO. + 2HC 2 H 3 2 = 2NaC 2 H 3 2 + HO + CO, 

Sodium Acetic Sodium Water. Carbonic 

carbonate. acid. acetate. acid gas. 

Sodium acetate effloresces in dry air, and loses all its waters of 
crystallization when gently heated. It supports a temperature of 
270° or 280° F. without decomposition, but above 300° soon chars. 

Sodium Bicarbonate. 

Fourth Synthetical Reaction. — The action of carbonic acid 
(H 2 C0 3 ), or carbonic acid gas (C0 2 ) and water (H 2 0), on 
sodium carbonate (Na 2 C0 3 ) resembles that on potassium car- 
bonate, but is applied in a different manner. The result is 
sodium bicarbonate (NaHC0 3 ), (Sodii Bicarbonas, Bicarbonate 
of Sodium, U. S. P.), the old bicarbonate of soda. 

Na 2 C0 3 + H 2 + C0 2 = 2NaHC0 3 . 

Sodium Water. Carbonic Sodium. 

carbonate. acid gas. bicarbonate. 

Process. — Heat crystals of sodium carbonate in a porcelain 
crucible until no more steam escapes. Rub the product in a* 
mortar with two-thirds its weight of more of the crystals, and 
place the powder in a test- 
tube or small bottle, into 
which carbonic acid gas may 
be conveyed by a tube pass- 
ing through a cork and ter- 
minating at the bottom of 
the vessel. To generate the 
carbonic acid gas, fill a test- 
tube having a small hole in 
the bottom (or a similar piece -- 

Of glass tubing of which one p re p ara tion of SodTu^carbonate 

end is plugged by a grooved 

cork) with fragments of marble, insert a cork and a delivery- 



* The " water" alluded to occurs in the acid, which, though commonly 
termed "acetic acid," is really a solution of that acid in water. 




84 THE METALLIC RADICALS. 

tube, and connect the latter with the similar tube of the vessel 
containing the sodium carbonate by a piece of india-rubber 
tubing. Now plunge the tube of marble into a test-glass or 
other vessel containing a mixture of 1 part hydrochloric acid 
and 2 parts water, and loosen the cork of the sodium carbonate 
tube until carbonic acid gas, generated in the marble tube, may 
be considered to fill the whole arrangement ; then replace the 
cork tightly and set the apparatus aside. As the gas is 
absorbed by the sodium carbonate, hydrochloric acid rises 
into the marble tube and generates fresh gas, which, in its 
turn, drives back the acid liquid, and thus prevents the pro- 
duction of any more gas until further absorption has occurred. 
When the salt is wholly converted into bicarbonate (NaHC0 3 ) 
it will be found to have become damp through the liberation 
of water from the crystallized carbonate (Na 2 CO 3 ,10H 2 O). (It 
would be inconveniently moist, even semi-fluid, if a part of 
the carbonate had not previously been rendered anhydrous.) 
On the large scale the resulting bicarbonate may be freed from 
any carbonate or traces of other salts by adding half its bulk 
of cold distilled water, setting aside for about half an hour, 
shaking occasionally, draining the undissolved portion, and 
drying it by exposure on filtering paper. 

This arrangement of apparatus for Sodii Bicarbonas, U. S. P., 
may be adopted for Potassii Bicarbonas, U. S. P., 1 part of car- 
bonate dissolved in 2 J parts of water being subjected to the 
action of the gas, and not the solid carbonate, as in the case of 
the sodium salt. 

The pure may be prepared from impure bicarbonate by wash- 
ing out any carbonate or traces of other salts, after introducing 
it into a percolator and passing water through it till the wash- 
ings cease to precipitate a solution of magnesium sulphate, 
when the sodium bicarbonate is removed from the percolator 
and dried on bibulous paper in a warm place. 

The sodium carbonate may be placed, not in a test-tube or 
bottle, but in a vertical tube, the bottom of which is loosely 
closed by a grooved cork. Any water of crystallization that is 
set free then runs off* (into a basin or cup beneath), and takes 
with it impurities (chlorides or sulphates, etc.) that may have 
been present in the original salt. 

Sodium Carbonates by u The Ammonia Process." 

Sodium bicarbonate is prepared by bringing to the elements 
of ammonium bicarbonate a strong solution of common salt ; 
the sodium bicarbonate is precipitated. 



SODIUM. 85 

NH 4 HC0 3 + NaCl = NaHC0 3 + NH 4 C1. 

Ammonium Sodium Sodium Ammonium 

bicarbonate. chloride. bicarbonate. chloride. 

The resulting ammonium chloride is reconverted into carbonate 
(p. 93), the latter more fully carbonated, and again used for 
producing sodium bicarbonate. Sodium carbonate {Soda Car- 
bonas, B. P.) is made by heating the bicarbonate thus obtained, 
the carbonic acid then liberated serving for the conversion of 
some ammonium carbonate into ammonium bicarbonate. 



2NaHC0 3 = 


= Na 2 C0 3 


+ 


H 2 


+ co 2 


Sodium 


Sodium 




Water. 


Carbonic 


bicarbonate. 


carbonate. 






acid gas. 



A crystal of sodium carbonate is sodium carbonate plus water ; 
on heating it more or less of the water is evolved, and anhydrous 
sodium carbonate is partially or wholly produced (Sodii Carbonas 
Exsiccatus, U. S. P.). 

Na 2 C0 3 ,10H 2 - 10H 2 = Na 2 C0 3 

Crystallized sodium Water Dried sodium 

carbonate (286). (180). carbonate (106). 

According to the United States Pharmacopoeia, dried sodium car- 
bonate is to be prepared by exposing crystals of sodium carbonate 
to warm air for several days to effloresce, and then to a temperature 
of about 45° C. until half the original weight is obtained. 286 parts 
would thus become 143, and the latter would thus still retain 37 
parts of water. In other words, the dried carbonate contains 72.6 
per cent, of anhydrous carbonate and 27.4 per cent, of water. The 
crystals contain, obviously, a little more than 37 per cent, of anhy- 
drous carbonate and nearly 63 per cent, of water. The student 
should verify all these figures. 

Note on Nomenclature. — Anhydrous bodies (from a and vdup, 
hudor, i. e. without water) are compounds from which water has 
been taken, but whose essential chemical properties are unaltered. 
Salts containing water are hydrous bodies ; of these the larger por- 
tion are crystalline, and their water is then termed water of crystal- 
lization. Non-crystalline hydrous compounds were formerly spoken 
of as hydrated substances : hydrates are, however, a distinct class 
of bodies, salts derived from water by one-half of its hydrogen 
becoming displaced by an equivalent quantity of another radical. 
Anhydrides form still another distinct class of chemical substances ; 
they are derived from acids : in short, they are acids from which 
not exactly water as water, but the elements of water, have been 
removed, the essential chemical (acid) properties being thereby 
greatly altered. (For illustrations, see Index, "Anhydrides.") 

Water of Crystallization. — The water in crystallized sodium car- 
bonate is in the solid condition, and, like ice and other fusible sub- 
stances, requires heat for its liquefaction. Many salts (freezing 
mixtures) when dissolved in water give a very cold solution. This 
is because they and their solid water, if they have any, are then, 
absorbing some heat from surrounding media, converted into liquids. 
Take away from water some of its heat, the result is ice. Give to 
5 



bb THE METALLIC RADICALS. 

ice (at 32° F.) more heat than it contains already, the result is water 
(still at 32° F.). (Heat thus taken into a substance without increas- 
ing its temperature is said to become latent — from latens. hiding ; it is 
no longer discoverable by the sense of touch or the thermometer. 
The term latent gives a somewhat incorrect idea, however, of the 
conditions ; for our knowledge of the extent and readiness with 
which one form of force is convertible into another renders highly 
probable the assumption that heat is in these cases converted into 
motion, the latter enabling the molecules of a solid to take up the 
new positions demanded by their liquid condition.) The only 
apparent difference between ice and the water in such crystals as 
sodium carbonate is that ice is solid water in the free, and water of 
crystallization solid water in the combined state. The former can 
only exist at and below 32° F. 5 the latter may exist at ordinary 
temperatures. Salts which unite with little or even no water of 
crystallization at common temperatures, but take up much at very low 
temperatures, are termed cryohydrates (upvog, kruos, icy cold, frost). All 
water of crystallization is dispelled at high temperatures. In chemical 
formulae the symbols representing water are usually separated by a 
comma from those representing salts. The crystals of sodium acetate 
(of the third reaction) contain water in this loose state of combination 
— water of crystallization (NaC 2 H 8 2 ,3H 2 0). It is possible, however, 
that this so-called water of crystallization is in a more intimate state 
of combination than is indicated by such a formula as that just 
given. 

" Soda-water.''' 1 — A solution of sodium bicarbonate in water charged 
with carbonic acid gas under pressure constitutes the official Liquor 
Sodce ~Effiervescens,B. P., and like the official " potash-water " is a 
true medicine, an antacid. The ordinary b ever age " soda-water " is 
commonly a simple solution of carbonic acid gas in water, and 
would be more appropriately termed "aerated water : " any medicinal 
effect it may possess is due to the sedative influence of its carbonic 
acid gas on the coats of the stomach. Originally it contained a 
little " soda" and was a mild antacid, but the public took to it as a 
mere beverage, refusing to drink it if it contained an y " soda," yet 
persisted, and still persist, in calling it " soda-water." At common 
temperatures water dissolves about its own volume of carbonic acid gas, 
both being under the same pressure. 1 pint of the official soda-water 
contains 30 grains of sodium bicarbonate and a pint of carbonic acid 
gas ; but the solution is under a pressure of four atmospheres, in 
addition to the ordinary pressure of our atmosphere, five atmospheres 
altogether, so that 5 pints of the gas at ordinary atmospheric pres- 
sure are required for the quantity mentioned. 

Solubility of Gases in Water. — Whatever the weight and volume 
of a gas dissolved by a liquid at ordinary atmospheric pressure, that 
weight is doubled by double pressure, the two original volumes of 
gas thereby being reduced to one ; trebled at treble pressure, the 
three original volumes of gas being reduced to one ; quadrupled at 
quadruple pressure, the four original volumes of gas being reduced 
to one ; and so on. This is a general law (Henry and Dalton) 
regarding the solubility of gases in liquids under given temperatures. 



SODIUM. 87 

An average bottle of " soda-water " contains about five times the 
weight of carbonic acid gas which can exist in it without artificial 
pressure, so that on removing its cork four times its bulk escapes, its 
own bulk remaining dissolved. 

Note. — Sodium bicarbonate may also be medicinally administered 
in the form of lozenge (Trochisci Sodii Bicarbonatis, B. P.). 

Sodium and potassium carbonate is officially distinguished from 
the bicarbonate by the former giving a reddish color with phenol- 
phtalein, and the latter no color at all. 

Potassium and Sodium Tartrate. 

Synonyms.. — Tartrate of Potassium and Sodium ; Tartrate of Pot- 
ash and Soda ; Rochelle Salt. 

Fifth Synthetical Reaction. — To some hot strong solution of 
sodium carbonate (about 3 parts) t in a test-tube or larger vessel, 
add acid potassium tartrate (about 4 parts) till no more effer- 
vescence occurs ; when the solution is cold crystals of the potas- 
sium and sodium tartrate (Soda Tartarata, B. P., Potassii et 
Sodii Tartras, U. S. P.) will be deposited (KNaC 4 H 4 6 ,4H 2 0). 
The crystals are usually halves of right rhombic prisms. 

Na 2 C0 3 + 2KHC 4 H 4 6 = 2KNaC 4 H 4 6 + H 2 + C0 2 

Sodium Acid potassium Potassium and Water. Carbonic 

carbonate. tartrate. sodium tartrate. acid gas-' 

Tartaric acid HHC 4 H 4 6 

Acid potassium tartrate KHC 4 H 4 6 

Potassium and sodium tartrate KNaC 4 H 4 6 

Very close analogy will be noticed in the above formulas, indicat- 
ive of the analogy in the constitution of the molecules of these salts. 
"When the other tartrates come under notice, it will be found that 
they also have a similar constitution. 

Sodium Hypochlorite. 

Synonyms. —Hypochlorite of Sodium-, Hypochlorite of Soda; 
Chlorinated Soda. 

Sixth Synthetical Reaction. — Triturate in a mortar 75 grms. 
of chlorinated lime with 200 cc. of water ; make up to 400 cc, 
and filter. Wash with 100 cc. of water. Dissolve 150 grms. 
of sodium carbonate in 300 cc. of hot water, and add to the 
clear solution of chlorinated lime ; thoroughly mix and filter and 
wash with enough water to make the product weigh 1000 grms. 
and Liquor Sodse, Chloratse, U. S. P. (" Labarraque's solu- 
tion ") results. It should have a sp. gr. of 1.052. 

CaCl 2 2 CaCl 2 + 2Na 2 C0 3 = (NaC10,NaCl) 2 -f- 2CaC0 3 

Chlorinated Sodium Chlorinated Calcium 

lime. carbonate. soda. carbonate. 



88 THE METALLIC RADICALS. 

This solution is an old and very useful disinfectant, formerly 
known as Labarraque's Liquor and Eau de Javelle. It contains at 
least 2.6 per cent, of available chlorine. 

Sodium Iodide and Bromide. 

Synonyms. — Bromide and Iodide of Sodium. 

These salts (Nal and NaBr), Sodii Iodidum, U. S. P., and Sodii 
Bromidum, U. S. P., are similar to potassium iodide and bromide in 
constitution, and are prepared with the same manipulations, soda 
being used in place of potash. The sodium bromide, however, must 
be crystallized from warm solutions, or rhombic prisms containing 
water (NaBr,2H 2 0) will be deposited. 

Other Sodium Compounds. 

Synthetical Reactions portraying the chemistry of the remaining 
official compounds (namely, sodium nitrate, sulphate, hyposulphite, 
borate, arseniate, valerianate, and ethylate) are deferred until the 
several acidulous radicals of these salts have been described. 

Sodium Phosphate.— -The preparation and composition of this salt 
will be most usefully studied after bone-ash, the source of it and 
other phosphates, has been described. Bone-ash is calcium phos- 
phate. (See page 113.) 

The official Citro- Tartrate of Sodium (Sodii Citro-tartras Effer- 
vescens, B. P.), the old citro-tartrate of soda, is a mixture of sodium 
bicarbonate (17 parts), citric acid (6), tartaric acid (9), and sugar 
(5), mixed and heated (to 200° or 220° F.) until the particles aggre- 
gate to a granular condition. When required for medicinal use a 
dose of the mixture is placed in water 5 escape of carbonic acid gas 
at once occurs, and an effervescing liquid results. This substance 
may be regarded as the official representative of the popular " effer- 
vescing citrate of magnesia," so called, which will be further noticed 
in connection with the salts of magnesium (p. 121). 

" Lemon and Kali " is a pulverulent mixture of sodium bicarbo- 
nate, tartaric acid, sugar, and essence of lemon. It was invented 
and so named by one Charles Gomond Cooke, who long retained a 
trade monopoly in the article by thus hiding the " soda" under its 
ancient name of " kali " (see p. 32), heightening the mystery by the 
prefix " Lemon and". 

Sodii Phosphas Effervescens, B. P., and Sodii Sulphas Efferves- 
cens, B. P., are the respective anhydrous salts mixed with sodium 
bicarbonate and tartaric and citric acids. 

Soda Powders (Pulveres Effervescentes, U. S. P. 1870). — Formed 
of 30 grains of sodium bicarbonate and 25 of tartaric acid, wrapped 
separately in papers of different colors. When mixed with water 
carbonic acid gas escapes, and sodium tartrate (Na 2 C 4 H 4 6 ) results, 
a little bicarbonate also remaining. 

In the manufacture of sodium carbonate, the old carbonate of 
soda, the source of the sodium is sodium chloride, and of the carbo- 
nic radical calcium carbonate in the form of limestone. By " the 
Le Blanc process" the chloride is converted into sulphate, the sul- 



SODIUM. 89 

phate then roasted with coal and limestone, and the resulting black 
ash lixiviated (lixivia, from lix, lye — water impregnated with 
alkaline salts ; hence lixiviation, the operation of washing a mixture 
with a view of dissolving out salts). If relatively small quantities 
of solvents be employed, the solution by lixiviation will be more or 
less fractional, salts of varying solubility being thus more or less 
separated from each other. The lye, evaporated to dryness, yields 
crude sodium carbonate (soda-ash). By "the ammonia process" 
the sodium carbonate is obtained by heating sodium bicarbonate, 
the latter by mixing strong solutions of sodium chloride and 
ammonium bicarbonate. The last-named salt results from the 
action of carbonic acid gas (liberated on heating the sodium bicarbo- 
nate) on ammonium carbonate, and this again from ammonium 
chloride and limestone. By either process common salt and lime- 
stone are the ordinary prime sources respectively of the sodium 
and the carbonic radical in sodium carbonate. The processes will 
be further described in connection with Carbonates. 

Deliquescence and Efflorescence. — The sodium and potassium car- 
bonates, chemically closely allied, differ physically. Potassium 
carbonate quickly absorbs moisture from the air and becomes damp, 
wet, and finally fluid ; it is deliquescent (deliquescens, melting away). 
Sodium carbonate, on the other hand yields water of crystallization 
to the air, the' crystals becoming white, opaque, and pulverulent ; it 
is efflorescent (efflorescens, blossoming forth, in allusion to the appear- 
ance of the product). 

Analogy of Sodium Salts to Potassium Salts. — Other synthetical 
reactions might be described similar to those given under Potassium, 
and thus sodium citrate, iodate, bromate, chlorate, manganate and 
permanganate, and many other salts be formed. But enough has 
been stated to show how chemically analogous sodium is to potas- 
sium. Such analogies will constantly present themselves. In few 
departments of knowledge are order and method more perceptible ; 
in few is there as much natural law, as much science, as in Chem- 
istry. 

Substitution of Potassium and Sodium Salts for Each Other. — 
Sodium salts being cheaper than potassium salts, the former may 
sometimes be economically substituted. That one is employed 
rather than the other is often merely a result due to accident or 
fashion. But it must be borne in mind that in some cases a potas- 
sium salt will crystallize more readily than its sodium analogue, or 
that a sodium salt is stable when the corresponding potassium salt 
has a tendency to absorb moisture, or one may be more soluble than 
the other, or the two may have different medicinal effects. For 
these or similar reasons a potassium salt has come to be used in 
medicine or trade instead of the corresponding sodium salt, and vice 
versa. Whenever the, acidulous portion only is to be utilized, the 
least expensive salt of the class would nearly always be selected. 

(b) Reactions having Analytical Interest. 
1. The chief analytical reaction for sodium is the flame-test. 
When brought into contact with a flame in the manner 



90 THE METALLIC RADICALS. 

described under Potassium (page 80), an intensely yellow color 
is communicated to the flame by any sodium salt. This is 
highly characteristic — indeed, almost too delicate a test ; for if 
the point of the wire be touched by the fingers, enough salt 
(which is contained in the moisture of the hand) adheres to the 
wire to communicate a very distinct sodium reaction. These 
statements should experimentally be verified, the chloride, sul- 
phate, or any other sodium salt being employed. 

2. Sodium salts, like those of potassium, are not volatile. 
Prove this fact by the means described when treating of the 
effect of heat on potassium salts (p. 80). 



QUESTIONS AND EXEKCISES. 

How is the official solution of soda prepared ? Give a diagram or equa- 
tion. — Explain the action of sodium or potassium on water. What colors 
do these elements respectively communicate to flame? — How much 
sodium bicarbonate can be obtained from 2240 pounds of crystallized 
carbonate? Ans. 1316 lbs., nearly. — Sodium acetate: give formula, pro- 
cess, and equation. — Give a diagram showing the formation of sodium 
bicarbonate. — Why is a mixture of dried and undried sodium carbonate 
employed in the preparation of the bicarbonate ? — State the difference 
between anhydrous and crystallized sodium carbonate. — Define the terms 
anhydrous, hydrous, hydrate, anhydride. — What do you understand by 
water of crystallization ? — What is the nature of the official " Liquor Sodse 
Effervescens " 1 — How many volumes of gas (reckoned as at ordinary 
atmospheric pressure) are contained in any given volume of the official 
" soda-water " ? — What is the general law regarding the solubility of 
gases in liquids under pressure? — What is the systematic name of 
Rochelle salt? and how is the salt prepared? — What is the relation of 
Eochelle salt to cream of tartar and tartaric acid ? — Give the mode of 
preparation of the official solution of chlorinated soda, expressing the 
process by a diagram. — : How is the effervescing sodium citro-tartrate 
prepared? — Define deliquescence, efflorescence, and lixiviation. — State the 
relations of potassium salts to those of sodium. — How are sodium salts 
distinguished from those of potassium? 



AMMONIUM. 
Formula, NH 4 . Combining weight, 18. 

Memoranda. — The elements nitrogen and hydrogen, in the propor- 
tion of 1 atom to 4 (NH 4 ), are those characteristic of all the com- 
pounds about to be studied, just as potassium (K) and sodium (Na) 
are the characteristic elements of the potassium and sodium com- 
pounds. Ammonium is a univalent nucleus, root, or radical, like 
potassium or sodium, and the ammonium compounds closely resem- 
ble those of potassium or sodium. In short, if, for an instant, potas- 
sium or sodium be imagined to be compounds, the analogy between 
these three series of salts is complete. Ammonium is said to have 
been isolated, by Weyl, as an unstable dark-blue liquid, possessing 
a metallic lustre. 

Source. — The source of nearly all the ammoniacal salts met with 



AMMONIUM. 91 

in commerce is the ammonia gas (NII 3 ) obtained in distilling all 
kinds of coal in the manufacture of ordinary illuminating gas 
and of coke ; being derived, doubtless, from the nitrogen of the 
plants from which the coal has been produced. It is also a by- 
product in distilling paraffin oil from shale, and may be washed out 
of the furnace gases of iron-works. It is possible, however, to pro- 
duce ammonia from its elements. Thus, coal-dust, air, and vapor 
of water, all at a red heat, yield, according to Rickman and Thomp- 
son, gaseous ammonia. Salt added to the mixture prevents the 
further combustion of the formed ammonia, and ammonium chloride 
sublimes. Nitrogen and hydrogen passed over spongy platinum 
yield traces of ammonia. 

Ammonia. — When this gas (NH 3 ) comes into contact with the con- 
densed steam (H 2 0) in the process of cooling the coal-gas, the result- 
ing " ammoniacal liquor" is believed to contain ammonium hydrate 
(NH 4 HO), the analogue of potassium or sodium hydrate, KOII or 
NaOH. The grounds for this belief are the observed analogy of 
the well-known ammoniacal salts to those of potassium and sodium, 
the similarity of action of solutions of potash, soda, and ammonia 
on salts of most metals, and the asserted existence of crystals of an. 
analogous sulphur salt (NH 4 HS). 

Ammonium Chloride. — The ammonia of the " ammoniacal liquor " 
of the gas-works, liberated by heat and the concurrent action of 
lime on sulphydrate, carbonate, and other salts present, and passed 
into hydrochloric acid, yields crude ammonium chloride (sal-ammo- 
niac), NH 3 -\- IIC1 = NH 4 C1 ; and from this salt, purified, the others 
used in pharmacy are directly or indirectly made. Ammonium 
chloride (Ammonii Chloridum, U. S. P.) occurs in inodorous color- 
less minute crystals, or in translucent fibrous masses, tough and 
difficult to powder, soluble in water (1 in 10 is the " Solution of 
Chloride of Ammonium," U. S. P.), almost insoluble in alcohol. 

Ammonium chloride generally contains slight traces of iron oxy- 
chloride, tarry matter, and possibly chlorides of compound ammo- 
niums. (Vide "Artificial Alkaloids" in Index.) 

Ammonium Sulphate (NH 4 ) 2 S0 4 , the old sulphate of ammonia, 
results when the ammonia from the " ammoniacal liquor " is neutral- 
ized by sulphuric acid. It is largely used as a constituent of arti- 
ficial manure, and when purified by recrystallization is employed in 
pharmacy for producing double sulphate of ammonium and iron, etc. 

Volcanic Ammonia. — A very pure form of ammonia is that met 
with in volcanic districts and obtained as a by-product in the manu- 
facture of borax ; the crude boracic acid as imported contains 5 to 10 
per cent, of ammonium salts, chiefly sulphate, and double sulphates 
of ammonium with magnesium, sodium, and manganese (Howard). 

Reactions having (a) General, (b) Synthetical, and 
(c) Analytical Interest. 

Ammonium Amalgam (?). 
(a) General Reaction. — To 40 or 50 grains of dry mercury 
in a dry test-tube add one or two small pieces of sodium (freed 



92 THE METALLIC RADICALS. 

from adhering naphtha by gentle pressure with a piece of filter- 
paper), and amalgamate by gently warming the tube. To 
this amalgam, when cold, add some fragments of ammonium 
chloride and a strong solution of the same salt. The sodium 
amalgam soon begins to swell and rapidly increase in bulk, 
probably overflowing the tube. The light spongy mass pro- 
duced is the so-called ammonium amalgam, and the reaction is 
usually adduced as evidence of the existence of ammonium. 
The sodium of the amalgam unites with the chlorine of the 
ammonium chloride, while the ammonium is supposed to form 
an amalgam with the mercury. As soon as formed the amal- 
gam gives off hydrogen and ammonia gases ; this decomposition 
is nearly complete after some minutes, and mercury remains. 

(6) Reactions having Synthetical Interest. 
Ammonium Hydrate. 

Synonyms. — Hydrate of Ammonium ; Ammonia. 

First Synthetical Reaction. — Heat a few grains of sal-ammo- 
niac with about an equal weight of calcium hydrate (slaked 
lime) damped with a little water in a test-tube ; ammonia gas 
is given off, and may be recognized by its well-known odor. 
It is very soluble in water. Pass a delivery -tube fitted to the 
charged test-tube, as described for the preparation of oxygen 
and hydrogen, into a second test-tube, at the bottom of which 
is a little water ; again heat, the end of the delivery-tube being 
only just beneath the surface of the water (or, possibly, all the 
water might rush back into the generating-tube, water absorb- 
ing ammonia gas with great avidity) ; solution of ammonia 
(Liquor Ammonise, B. P., or Liquor Ammonise, Fortior, B. P.) 
will thus be formed. 

2NH 4 C1 -f Ca2HO = CaCl 2 -f 2H 2 + 2NH 3 

Ammonium Calcium Calcium Water. Ammonia 

chloride. hydrate. chloride. gas. 

A molecule of ammonia gas is composed of one atom of nitrogen 
with three atoms of hydrogen ; its formula is NH 3 . Two volumes 
of the gas contain one volume of nitrogen combined with three 
similar volumes of hydrogen. Its constituents have, therefore, in 
combining suffered condensation to one-half their normal bulk. Its 
conversion into ammonium hydrate may thus be shown : 
NH 3 + H 2 = NH 4 HO 

Ammonia Water. Ammonium hydrate 

gas. (ammonia). 

Solutions of Ammonia, prepared by this process on a large scale 
and in suitable apparatus, are met with in pharmacy — the one (sp. 
gr. 0.891) containing 32.5 per cent., the other (sp. gr. 0.959) 10 per 
cent, by weight of ammonia gas, NH 3 , or 66.9 and 20.6 of ammonia, 



AMMONIUM. 93 

NH 4 HO {Aqua Ammonice Fortior and Aqua Ammonice, U. S. P. : 1 
part, by measure, of the former and 2 of water form the latter). On 
the large scale, bottles are so arranged in a series as to condense all 
the ammonia evolved during the operation. Spiritus Ammonice, 
U. S. P., is an alcoholic solution of ammonia containing 10 per cent., 
by weight, of the gas (NH 3 ). 

Ammonium Acetate. 

Sijnonyms. — Acetate of Ammonium ; Acetate of Ammonia. 

Second Synthetical Reaction. — To acetic acid and water in a 
test-tube add powdered commercial ammonium carbonate (acid 
carbonate and carbamate) until effervescence ceases. A solution 
containing 7 per cent of ammonium acetate forms the official 
Liquor Ammonii Acetatis, U. S. P., the old " spirit of Minde- 
rerus." 

On evaporating and cooling, ammonium acetate (the old acetate of 
ammonia) may be obtained in crystals. 

NH 4 HC0 3 ,NH 4 NH 2 C0 2 + 3HC,H 3 2 = 3NH 4 C 2 H 3 2 + H 2 + 2C0 2 

Acid ammonium carbonate Acetic Ammonium Water. Carbonic 

and carbamate. acid. acetate. acid gas. 

Solution of ammonium acetate can, of course, be just as easily 
made by reaction of acetic acid and solution of ammonia (NH 4 HO) ; 
but the liquid, owing to absence of dissolved carbonic acid, is too 
vapid for use in pharmacy. 

Ammonium Carbonates. 

Synonyms. — Carbonates of Ammonium ; Carbonates of Ammonia. 

Commercial Ammonium Carbonate is made by heating a mixture 
of chalk and sal-ammoniac ; calcium chloride (CaCl 2 ) is produced, 
ammonia gas (NH 3 ) and water (H 2 0) escape, and the ammoniacal 
carbonate distils, or, rather, sublimes* in cakes {Ammonii Carbonas, 
U. S. P., the old carbonate of ammonia). The best form of appa- 
ratus to employ is a retort with a short wide neck and a cool receiver. 
On the large scale the retort is usually iron and the receiver earthen- 
ware or glass ; on the small scale glass vessels are employed. The 
salt is purified by resublimation at a low temperature — 150° F. is 
said to be sufficient. 

The salt, the empirical formula of which is N 3 H n C 2 5 , is prob- 
ably a mixture of one molecule (sometimes two) of acid ammonium 
carbonate (NH 4 HC0 3 ) and one of a salt termed ammonium carbamate 
(NH 4 NH 2 C0 2 ). The latter belongs to an important class of salts 
known as carbamates, but is the only one of direct interest to the 

* Sublimation (from sublimis, high), vaporization of a solid substance 
by heat, and its condensation on an upper and cooler part of the vessel 
or apparatus in which the operation is performed. Substances sublime 
at different temperatures, hence a mixture of volatile solids may some- 
times be separated or fractionated by sublimation. 
5* 



94 THE METALLIC RADICALS. 

pharmacist. Cold water extracts it from the commercial ammonium 
carbonate, leaving the acid carbonate or bicarbonate undissolved if 
the amount of liquid used be very small. Alcohol extracts the car- 
bamate, leaving the acid carbonate undissolved. In water the car- 
bamate soon changes into the neutral ammonium carbonate, 

NH 4 NH 2 C0 2 + H 2 = (NH 4 ) 2 C0 3 , 

so that an aqueous solution of commercial ammonium carbonate 
contains both acid and neutral ammonium carbonate. If to such a 
solution some ordinary solution of ammonia be added, a solution 
of the neutral ammonium carbonate only is obtained : and this is 
the common reagent always found on the shelves of the analytical 
laboratory. Thus, " Solution of Carbonate of Ammonium," B. P., 
is formed by dissolving \ an ounce of the salt in 10 ounces of water, 
to which f of an ounce of solution of ammonia has been added. 

NH 4 HC0 3 -f- NH 4 HO= (NH 4 ) 2 C0 3 + H 2 0. 

Neutral ammonium carbonate is the salt formed on adding strong 
solution of ammonia to the commercial carbonate in preparing a 
pungent mixture for toilet smelling-bottles ; but it is unstable, and 
on continued exposure to air is reduced to a mass of crystals of 
bicarbonate. 

If ammonium carbonate contain more than traces of empyreumatic 
matters (from the gas-liquors), an aqueous solution, with excess of 
sulphuric acid added, will decolorize a dilute solution of potassium 
permanganate at once. 

Sal Volatile {Spiritus Ammonice Aromaticus, U. S. P.) is a 
spirituous solution of about 1£ per cent, of ammonia gas (NH 3 ), 
nearly 3J per cent, of neutral ammonium carbonate, (NH 4 ) 2 C0 3 , 
and the oils of nutmeg, lemon, and lavender. Commercial samples 
contain salts equivalent to from 1 to nearly 3 per cent, of ammonia 
gas, the official spirit yielding a total of 1\ per cent, of the gas. 
Fetid spirit of ammonia {Spiritus Ammonice Fcetidus, B. P.) is an 
alcoholic solution of the volatile oil of asafoetida mixed with solution 
of ammonia. 

Ammonium Nitrate. 

Synonyms. — Nitrate of Ammonium ; Nitrate of Ammonia. 

Third Synthetical Reaction. — To some diluted nitric acid add 
ammonium carbonate, until, after well stirring, a slightly am- 
moniacal odor remains. The solution contains ammonium ni- 
trate (Ammonii JVitras, U. S. P., the old nitrate of ammonia). 

NH 4 HC0 3 ,NH 4 NH 2 C0 2 + 3HN0 3 = 3NH 4 N0 3 + H 2 + 2C0 2 

Acid ammonium carbonate Nitric Ammonium Water. Carbonic 

and carbamate. acid. nitrate. acid gas: 

From a strong hot solution of ammonium nitrate crystals may be 
obtained containing much water (NH 4 N0 3 ,12H 2 0). On heating 
these in a dish to about 320° F. the water escapes. The anhydrous 
salt remaining (NH 4 N0 3 ) may be poured on to an iron plate. On 
further heating the crushed nitrate at 350° to 450° F., it is resolved 



AMMONIUM. 95 

into nitrous oxide gas ("laughing gas") and water, NH 4 N0 3 = 
N 2 + 2H 2 0. 

Nitrous Oxide is thus prepared for use as an anaesthetic. When 
required for inhalation, it is washed from any trace of acid or nitric 
oxide by being passed through solution of potash and solution -of 
ferrous sulphate, the former absorbing acid vapors, the latter nitric 
oxide. It is slightly soluble in warm water, more so in cold. It 
supports combustion almost as well as oxygen. By pressure it may 
be liquefied to a colorless fluid, and by simultaneous cooling solidi- 
fied. 

Ammonium Citrate, Phosphate, and Benzoate. 

Synonyms. — Citrate, etc. of Ammonium ; Citrate, etc. of Ammonia. 

Fourth Synthetical Reaction. — To solution of citric acid 
(H 3 C 6 H 5 7 ) add solution of ammonia (NH 4 HO) until the well- 
stirred liquid smells faintly of ammonia. Solutions having the 
specific gravities, respectively, of 1.062 and (four times the 
strength) 1.209 form the official solutions of ammonium ci- 
trate, (NH 4 ) 3 C 6 H 5 7 (Liquor Ammonii Citratis, B. P., and Liq- 
uor Ammonii Citratis Fortior, B. P.). 

Ammonium Phosphate, (NH 4 ) 2 HP0 4 (Ammonii Phosphas, B. P.), 
and Ammonium Benzoate (NH^C^HjO,^ (Ammonii Benzoas, U. S P.), 
are also made by adding solution of ammonia to phosphoric acid 
(H 3 P0 4 ) and benzoic acid (HC 7 H 5 2 ), respectively, evaporating 
(keeping the ammonia in slight excess by adding more of its solu- 
tion), and setting aside for crystals to form. 



H,C 6 H 5 7 

Citric acid. 


+ 


3NH 4 HO 

Ammonia. 


= (NH 4 ) 3 C 6 H 5 7 + 

Ammonium citrate. 


3H 2 

Water. 


H 3 P0 4 

Phosphoric acid. 


+ 


2NH 4 HO 

Ammonia. 


= (NH 4 ) 2 HP0 4 + 

Ammonium phosphate. 


2H 2 

Water. 


HC 7 H 5 2 

Benzoic acid. 


+ 


NH 4 HO 

Ammonia. 


= NH 4 C 7 H 5 2 4- 

Ammonium benzoate. 


H 2 

Water. 



Ammonium phosphate occurs in transparent colorless prisms soluble 
in water, insoluble in spirit 5 benzoate in crystalline plates soluble 
in water and in spirit. 

Ammonium Bromide (U. S. P.) will be noticed in connection with 
Hydrobromic Acid and other bromides, and the Ammonii Iodidum 
(U. S. P.) with the other iodides. 

Ammonium Oxalate. 

Synonyms. — Oxalate of Ammonium 5 Oxalate of Ammonia. 

Fifth Synthetical Reaction. — To a nearly boiling solution of 
1 part of oxalic acid in about 8 of water add ammonium carbonate 
until the liquid is neutral to test-paper (see following paragraphs), 
filter while hot, and set aside for crystals to form. The product is 
Ammonium Oxalate, U. S. P. (Oxalate of Ammonium, B. P.), 
(NH 4 ) 2 C 2 4 ,H 2 0, the old oxalate of ammonia. The mother- 



96 THE METALLIC KADICALS. 

liquor is useful as a reagent in analysis ; one of the pure salt in 
forty of water forms " Solution of Oxalate of Ammonium," B. P. 

3H 2 C ? 4 -f 2N 3 H n C 2 5 = 3(NH 4 ) 2 C 2 4 + 4C0 2 + 2H 2 

Oxalic Animoniuin Ammonium Carbonic Water, 

acid. carbonate. oxalate. acid. gas. 

Neutralization. — Thus far, the methods by which the student has 
avoided excess of either acid matter on the one hand or alkaline 
on the other have been the rough aid of taste, cessation of efferves- 
cence, presence or absence of odor, etc. More delicate aid is afforded 
by test-papers. 

Test-papers. — Litmus (B. P.) is a blue vegetable pigment prepared 
from various species of Roccella lichen, exceedingly sensitive to the 
action of acids, which turn it red. When thus reddened, alkalies 
(potash, soda, and ammonia) and other soluble hydrates readily turn 
it blue. The student should here test for himself the delicacy of 
this action by experiments with paper soaked in solution of litmus 
and dipped into very dilute solutions of acids, acid salts (KHC 4 H 4 6 , 
e. g.), alkalies, and such neutral salts as potassium nitrate, sodium 
sulphate, or ammonium chloride. 

Solution of Litmus (U. S. P.). — This is prepared from purified 
litmus. Gently boil litmus with three times its bulk of spirit 
of wine for an hour. Pour away the fluid and repeat the operation 
twice. Digest the residual litmus in distilled water and filter. 

Blue Litmus-paper (U. S. P.) is unsized white paper colored by a 
solution of litmus and dried by exposure to the air. 

Red Litmus-paper (U. S. P.) is unsized white paper colored with 
solution of litmus previously reddened by the smallest requisite 
quantity of hydrochloric acid, and dried by exposure to the air. 

Turmeric-paper (IT. S. P.), similarly prepared from tincture of 
turmeric (one of washed turmeric-root or rhizome to six of rectified 
spirit, macerated for several days), is occasionally useful as a test for 
alkalies, which turn its yellow color to brown ; acids do not affect it. 

Other " indicators " of alkalinity or acidny are used. 

Ammonium Sulphydrate. 

Synonyms. — Sulphydrate of Ammonium ; Sulphydrate of Am- 
monia. 

Sixth Synthetical Reaction. — Pass sulphuretted hydrogen 
gas (H 2 S) through a small quantity of solution of ammonia 
in a test-tube, until a portion of the liquid no longer causes 
a white precipitate in solution of magnesium sulphate ; the 
product is a solution of ammonium sulphydrate (NH 4 HS), 
erroneously termed ammonium sulphide, a valuable chemical 
reagent, as will presently be apparent : 

NH 4 HO -f H 2 S = NH 4 HS -f- H 2 0. 

" Ammonium Sulphide Test-solution," U. S. P., of official strength 
is made by passing the gas, prepared as described on the next page, 



AMMONIUM. 



97 



into 300 cc. of ammonia solution (Aqua Ammonia?) so long as the 
gas continues to be absorbed, then adding 200 cc. more of ammonia 
solution, and preserving in a well-stoppered bottle. 

Sulphur etted Hydrogen (Hydrogen Sulphide, Sulphuric Acid, 
or Hydrosulphuric Acid) is a compound of noxious odor ; hence 
the above operation, and many others described farther on, in 
which this gas is indispensable, can only be performed in the 
open air or in a fume-cupboard — a chamber so contrived that 
deleterious gases and vapors shall escape into a chimney in 
connection with the external air. In the above experiment 
the small quantity of gas required can be made in a test-tube, 
after the manner of hydrogen itself. To some fragments of 
ferrous sulphide (FeS) add water, and then sulphuric acid ; the 
gas is at once evolved, and may be conducted by a tube into the 
solution of ammonia. Ferrous sulphate remains dissolved : 

FeS + H 2 SO, = H 2 S -f FeS0 4 . 

Sulphuretted-hydrogen Apparatus. — As no heat is necessary 
in making sulphuretted hydrogen (U. S. P.), the test-tube of 
the foregoing operation may be advantageously replaced by a 
bottle, especially when larger quantities of the gas are required. 
In analytical operations the gas should be purified by passing 
it through water contained in a second bottle. 



Fig. 18. 




Sulphuretted-hydrogen Apparatus. 

The most convenient arrangement for experimental use is 
prepared as follows : Two common wide-mouth bottles are 
selected, the one having a capacity of about half a pint, the 
other a quarter pint ; the former may be called the generating- 
bottle, the latter the ivash-bottle. Fit two corks to the bottles. 
Through each cork bore two holes, with a round file or other 
instrument, of such size that glass tubing of about the diam- 



98 THE METALLIC RADICALS. 

eter of a quill pen shall fit them tightly. Through one of the 
holes in the cork of the generating-bottle pass a funnel-tube, so 
that its extremity may nearly reach the bottom of the bottle. To 
the other hole adapt a piece of tubing six inches long and bent 
in the middle to a right angle. A similar " elbow-tube " is fitted 
to one of the holes in the cork of the wash-bottle, and another 
elbow-tube, one arm of which is long enough to reach to near 
the bottom of the wash-bottle, fitted to the other hole. Re- 
moving the corks, two or three ounces of water are now poured 
into each bottle, an ounce or two of ferrous sulphide put into 
the generating-bottle, and the corks replaced. The elbow-tube 
of the generating-bottle is now attached by a short piece of 
india-rubber tubing to the long-armed elbow-tube of the wash- 
bottle, so that gas coming from the generator may pass through 
the water into the wash-bottle. The delivery -tube of the wash- 
bottle is then lengthened by attaching to" it, by india-rubber 
tubing, another piece of glass tubing several inches in length. 
The apparatus is now ready for use. Strong sulphuric acid is 
poured down the funnel-tube in small quantities at a time, 
until brisk effervescence is established, and more added from 
time to time as the evolution of gas becomes slow. The gas 
passes through the tubes into the wash-bottle, where, as it 
bubbles up through the water, any trace of sulphuric acid or 
other matter mechanically carried over is arrested, and thence 
the gas flows out at the delivery -tube into any vessel or liquid 
that may be placed there to receive it. The generator must be 
occasionally dismounted and the ferrous sulphate washed out. 

Luting (lutum, mud). — If the corks of the above apparatus are 
sound and the tube-holes well made, no escape of gas will occur. 
If rough corks have been employed or the holes are not cylindrical, 
linseed-meal lute may be rubbed over the defective parts. The lute 
is prepared by mixing linseed meal with water to the consistence 
of dough. A neat appearance may be given to the lute by gently 
rubbing a well-wetted finger over its surface. 

(c) Reactions having Analytical Interest ( Tests'). 

First Analytical Reaction. — To a solution of an ammonium 
salt (chloride, for example) in a test-tube add solution of soda 
(or potash, or slaked lime), and well shake or warm ; a charac- 
teristic odor (ammonia, NH 3 ) results : 

NH 4 C1 + NaHO = NH 3 4- H 2 + NaCl. 

Though ammonium itself cannot be obtained in the free state, its 
compounds are stable. Ammonia is easily expelled from those 
compounds by action of the stronger alkalies, caustic potash, soda, 



AMMONIUM. 99 

or lime. As a matter of exercise the student should here draw out 
equations in which ammonium acetate (NH 4 C 2 H 3 2 ), sulphate 
(NH 4 ) 2 S0 4 , nitrate (NH 4 N0 3 ), or any other ammoniacal salt, not 
already having the odor of ammonia, is supposed to be under 
examination ; also equations representing the use of the other 
hydrates (KHO or Ca2HO). 

The odor of ammonia is the best means of recognizing its 
presence ; but the following tests are occasionally useful : Into 
the upper part of the test-tube insert a glass rod moistened 
with strong hydrochloric acid (that is, with the solution of 
hydrochloric acid gas conventionally termed hydrochloric acid, 
the Acidum Hydrochloricum of the pharmacopoeias) ; white fumes 
of ammonium chloride will be produced : NH 3 + HC1 = NH 4 C1. 
Hold a piece of moist red litmus-paper in a tube in which is 
ammonia gas ; the red color will be changed to blue. 

Second Analytical Reaction. — To a few drops of a solution 
of an ammonium salt add a drop or two of hydrochloric acid 
and a like small quantity of solution of platinum perchloride 
(PtCl 4 ) ; a yellow crystalline precipitate (the double platinum 
and ammonium chloride, PtCl 4 ,2NH 4 Cl) will be produced, simi- 
lar in appearance to the corresponding potassium salt, the 
remarks concerning which (p. 79) are equally applicable to the 
precipitate under notice. 

Third Analytical Reaction. — To a moderately strong solution 
of an ammonium salt add a strong solution of tartaric acid, and 
shake or well stir the mixture ; a white granular precipitate 
(acid ammonium tartrate) will be formed. 

For data from which to draw out an equation representing this 
action see the remarks and formulas under the analogous potassium 
salt (p. 79). 

Fourth Analytical Fact. — Evaporate a few drops of a solu- 
tion of an ammonium salt to dryness, or place a fragment of a 
salt in the solid state on a piece of platinum-foil, and heat in 
a flame ; the salt is readily volatilized. As already noticed, the 
salts of potassium and sodium are fixed under these circum- 
stances, a point of difference of which advantage will frequently 
be taken in analysis. A porcelain crucible may often be advan- 
tageously substituted for platinum-foil in experiments on 
volatilization. 

Salts of ammonium with the more complex acidulous radicals 
seldom volatilize unchanged when heated. The oxalate, when 
warmed, loses its water of crystallization, and at a higher tem- 
perature decomposes, yielding carbonic oxide, carbonic acid gas, 
ammonia gas, water (the three latter sometimes in combination), 



100 



THE METALLIC RADICALS. 



and several organic substances. The phosphate yields more or 
less phosphoric acid as a residue. 

A wire triangle may be used in supporting crucibles (Fig. 19). It 
is made by twisting together each pair of ends of three (five- or six- 
inch) crossed pieces of wire (Fig. 20). A piece of tobacco-pipe stem 
(about two inches) is sometimes placed in the centre of each wire 
before twisting, the transference of any metallic matter to the sides 
of the crucible being thus prevented (Fig. 21). 



Fig. 19. 



Fig. 20. 



Fig. 21. 




Triangular Supports for Crucibles. 



Practical Analysis. 

With regard to those of the preceding experiments which are use- 
ful rather as means of detecting the presence of potassium, sodium, 
and ammonium than as illustrating the preparation of salts, the so- 
called " tests," the student should proceed to apply them to certain 
solutions of any of the salts of potassium, sodium, and ammonium, 
with the view of ascertaining which metal is present ; that is, pro- 
ceed to practical analysis.* A little thought will enable him to 
apply these reactions in the most suitable order and to the best 
advantage for the contemplated purpose ; but the following arrange- 
ments are perhaps as good as can be devised : 

* Such solutions are prepared in educational laboratories by a tutor. 
They should, under other circumstances, be mixed by a friend, as it is 
not desirable for the student to know previously what is contained in the 
substance he is about to analyze. 

The analysis of solutions containing only one salt serves to impress the 
memory with the characteristic tests for the various metals and other 
radicals, and familiarize the mind with chemical principles. Medical 
students seldom have time to go farther than this. More thorough analyt- 
ical and general chemical knowledge is only acquired by working on 
such mixtures of bodies as are met with in actual practice, beginning 
with solutions which may contain any or all of the members of a group. 
Hence in this Manual two tables of short directions for analyzing are 
given under each group. Pharmaceutical students should follow the 
second. 



AMMONIUM. 101 

DIRECTIONS FOR APPLYING THE FOREGOING ANALYTICAL 
REACTIONS TO THE ANALYSIS OF AN AQUEOUS SOLUTION 
OF A SALT OF ONE OF THE METALS, POTASSIUM, SODIUM, 
AMMONIUM. 

To a small portion of the solution to be examined in a test- 
tube add caustic soda, and warm the mixture ; the odor of 
ammonia gas reveals the presence of an ammonium salt. 

If ammonium be not present, apply the platinum perchloride 
test to another portion of the liquid ; a yellow precipitate 
proves the presence of potassium. 

(It will be observed that potassium can only be detected in 
the absence of ammonium, salts of the latter radical giving 
similar precipitates.) 

The flame test is sufficient for the recognition of sodium. 



DIRECTIONS FOR APPLYING THE FOREGOING ANALYTICAL 
REACTIONS TO THE ANALYSIS OF AN AQUEOUS SOLUTION 
OF SALTS OF ONE, TWO, OR ALL THREE OF THE 
ALKALI METALS. 

Commence by testing a small portion of the solution for an 
ammonium salt. If it be present, make a memorandum to that 
effect, and then proceed to get rid of the ammoniacal compound 
to make way for the detection of potassium ; advantage is here 
taken of the volatility of ammonium salts and the fixity of 
those of potassium and sodium. Evaporate the original solu- 
tion to dryness in a small basin, transfer the solid residue to a 
porcelain crucible, and heat the latter to low redness, or until 
dense white fumes (of ammoniacal salts) cease to escape. (See 
Fig, 19.) This operation should be conducted in a fume-cup- 
board, to avoid contamination of the air of the laboratory. 
When the crucible is cold, dissolve out the solid residue with a 
small quantity of hot water, and test the solution for potassium 
by the platinum perchloride test, and for sodium by the flame 
test. 

When the starting test has shown absence of ammonium, the 
original solution may, of course, at once be tested for potassium 
and sodium. 

Flame Test — The violet tint imparted to flame by potassium salts 
may be seen when masked by the intense yellow color due to sodium 
if the flame be observed through a piece of dark-blue glass, a 
medium which absorbs the yellow rays of light. 



102 THE METALLIC RADICALS. 

Note on Nomenclature. — The operations of evaporation and heating 
to redness, or ignition, are frequently necessary in analysis, and are 
usually conducted in the above manner. If vegetable or animal 
matter be also present, carbon is set free, and ignition is accompanied 
by carbonization ; the material is said to char. When all carbon- 
aceous matter is burnt off, the crucible being slightly inclined and 
its cover removed to facilitate combustion, and mineral matter, or 
ash, alone remains, the operation of incineration has been effected. 

Note on the Classification of the Elements. — The compounds of 
potassium, sodium, and ammonium have many analogies. Their 
carbonates, phosphates, and other common salts are soluble in water. 
The atoms of the three radicals are univalent ; that is, each dis- 
places or is displaced by one atom of hydrogen. In fact, these 
radicals constitute by their similarity in properties a distinct group 
or family. All the elements thus naturally fall into classes — a fact 
that should constantly be borne in mind, and evidence of which 
should always be sought. It would be impossible for the memory 
to retain the details of Chemistry without a system of classification 
and leading principles. Classification is also an important feature 
in the art as well as in the science of Chemistry, for without it prac- 
tical analysis could not be undertaken. The classification adopted 
in this volume is founded on the quantivalence of the elements and 
on their analytical relations. 



QUESTIONS AND EXERCISES. 

Why are ammoniacal salts classed with those of potassium and sodium ? 
— Mention the sources of the ammonium salts. — Describe the characters 
of ammonium chloride. — Give the formula of ammonium sulphate. — Ad- 
duce evidence of the existence of ammonium. — How is the official solution 
of ammonia prepared ? Give a diagram. — How is the official solution of am- 
monium acetate prepared ? — What is the composition of commercial am- 
monium carbonate ? — Define sublimation. — What ammoniacal salts are 
contained in Spiritus Ammonite Aromaticus, U. S. P. ? — Give diagrams or 
equations illustrating the formation of ammonium citrate, phosphate, 
and benzoate. — Give the formula of ammonium oxalate. — How is ammo- 
nium hydrate converted into sulphydrate ?— Describe the preparation of 
sulphuretted hydrogen gas. — Enumerate and explain the tests for ammo- 
nium. — How is potassium detected in a solution in which ammonium 
has been found ? — Give equations illustrating the action of sodium 
hydrate on ammonium acetate ; potassium hydrate on ammonium sul- 
phate ; and calcium hydrate on ammonium nitrate. — What are the effects 
of acids and alkalies on litmus and turmeric ? — Describe the analysis of 
an aqueous liquid containing potassium, sodium, and ammonium salts. — 
What meanings are commonly assigned to the terms evaporation, ignition, 
carbonisation, and incineration ? — Write a short article descriptive of the 
analogies of potassium, sodium, and ammonium, and their compounds. 



BARIUM. 103 

BARIUM, CALCIUM, MAGNESIUM. 

These three elements have many analogies. Their atoms are 
bivalent. 

BARIUM. 

Symbol, Ba. Atomic weight, 137. 

The analytical reactions of this metal are those which are of chief 
interest to the general student of pharmacy. The barium nitrate, 
the old nitrate and baryta or nitrate of harytes (Ba2N0 3 ), and the 
chloride (BaCl 2 ,2H 2 0), are the soluble salts in common use in analy- 
sis (Chloride of Barium, B. P., and test-solution of barium chloride, 
1 in 10 of water, U. S. P.) ; and these and others are made by dis- 
solving the native carbonate (BaC0 3 ), the mineral witherite, in acids, 
or by heating the other common natural barium compound, the sul- 
phate, heavy white or heavy spar (BaSOJ, with coal, which yields 
barium sulphide (BaS), (BaS0 4 -\- C 4 — 4CO -\- BaS) and dissolving 
the sulphide in appropriate acids. When the nitrate is strongly 
heated, it is decomposed, barium oxide or baryta (BaO) remaining. 
Baryta, on being moistened, assimilates the elements of water with 
great avidity, and yields barium hydrate (Ba2HO). The latter is 
tolerably soluble, giving baryta-water ; and from this solution crys- 
tals of barium hydrate (Ba2HO,8H 2 0) are obtained on evaporation. 

The operations above described may all be performed in test-tubes 
and small porcelain crucibles heated by the gas flame. Quantities 
of 1 oz. to 1 ft), require a coke furnace. 

Barium Peroxide. 

Synonyms. — Peroxide of Barium ; Barium Dioxide. 

Barium Peroxide (Ba0 2 ) is formed on passing air over baryta 
heated to about 600° F. On raising the temperature oxygen is 
evolved and baryta remains. This is Boussingault's old process, but 
the baryta loses its absorbing power after a time. If the air be freed 
from carbonic acid gas, and the peroxide be not exposed to a much 
higher temperature than 800° F. (by heating in a vacuum), the 
baryta can be used over and over again. This improvement is by 
Messrs. Brin, who sell the oxygen compressed within strong metal 
cylinders. Barium peroxide is now official {Barii Dioxidum, U. S. 
P.). It is a heavy white amorphous powder without odor or taste ; 
exposed to air it gradually absorbs moisture and carbon dioxide, and 
is thus slowly decomposed. It is almost insoluble in, but forms a 
definite hydrate with, cold water. 

Quantivalence. — The atom of barium is bivalent, Ba". 

Hydrogen Peroxide, or Peroxide of Hydrogen. 

Hydrogen peroxide (H 2 2 ) is prepared by the action of dilute acid 
on barium peroxide. A solution of the oxide is thus obtained, the 
old oxygenated water. Aqua Hydrogenii Dioxidi, U. S. P., is officially 
prepared by suspending barium peroxide in water, and well shaking 
every few minutes for half an hour, keeping the temperature below 



104 THE METALLIC RADICALS. 

10° C. Then continue to shake occasionally until all the peroxide 
has been hydrated, which is easily determined by the fact that 
hydrated oxide of barium does not settle to the bottom on standing. 
Dilute phosphoric acid (nine of water to two of acid) is then care- 
fully added until the liquid remains just neutral after being well 
agitated. The precipitated barium phosphate is then allowed to 
settle, and filtered. Dilute sulphuric acid is then added to the 
filtrate, until small portions filtered give no further precipitate on 
the addition of more acid. Starch may be used to assist filtration. 
The amount of H 2 2 is finally ascertained by the official method (see 
Index) and made up to the proper strength. 

The solution of hydrogen peroxide made as above should contain 
about 3 per cent, by weight of the pure peroxide. It is a liquid with- 
out color or odor, but having a slightly acid taste and a specific grav- 
ity about 1.006-1.012. When exposed to the air the solution loses 
water, and if heated is liable to decompose suddenly. In the official 
solution a little free acid is allowed to remain to preserve it ; on 
evaporation should not leave more than 0.5 per cent, of solid matter. 

Tests. — If some water be mixed in a test-tube with a drop of 
potassium chromate, a drop or two of dilute sulphuric acid, and a 
few cc. of ether run on the top, then one or two drops of a solution 
of hydrogen peroxide added, on well shaking the solution the ether 
becomes colored blue. 

On neutralizing a solution of hydrogen peroxide with ammonia 
and adding potassium permanganate, oxygen gas is given off, its 
volume indicating the oxygen "volume strength" of the original 
solution. 

Reactions having Analytical Interest (Tests). 
First Analytical Reaction. — To the aqueous solution of any 
soluble barium salt (nitrate or chloride, for example) add dilute 
sulphuric acid ; a white precipitate .is obtained. Set the test- 
tube aside for two or three minutes, and when some of the pre- 
cipitate has fallen to the bottom pour away the supernatant 
liquid, wash the precipitate by adding water, shaking, setting 
aside, and again decanting ; and then add strong nitric acid, and 
boil ; the precipitate is insoluble. 

The production of a white precipitate by sulphuric acid, insoluble 
even in hot nitric acid, is highly characteristic of barium. The 
name of this precipitate is barium sulphate ; its formula is BaS0 4 . 

Antidotes. — In cases of poisoning by soluble barium salts obvious 
antidotes would be solution of alum or of any sulphates, such as 
those of magnesium and sodium (Epsom salt, Glauber's salt). 

Second Analytical Reaction. — To a barium solution add solu- 
tion of the yellow potassium chromate (K 2 Cr0 4 ) ; a pale yel- 
low precipitate (barium chromate, BaCr0 4 ) falls. Add acetic 
acid to a portion, it is insoluble. Add hydrochloric or nitric 
acid to another portion, it is soluble. 



CALCIUM. 105 

" Neutral Chromate." — The red potassium chromate (or bichro- 
mate) (K 2 Cr0 4 ,Cr0 3 ) must not be used in this reaction, or the barium 
will be only imperfectly precipitated ; for the red salt gives rise to the 
formation of free acid, in which barium chromate is to some extent 
soluble : 

K 2 Cr0 4 ,Cr0 3 + 2BaCl 2 -f H 2 = 2BaCr0 4 -f 2KC1 + 2HC1. 

The yellow chromate is obtained on adding potassium bicar- 
bonate, 200 grains, in small quantities at a time, to a hot solution of 
the red chromate, about 295 grains, until effervescence ceases. The 
product, diluted to 10 fluidounces, is " Solution of Yellow Chromate 
of Potassium," B. P. 

K 2 Cr0 4 ,Cr0 3 + 2KHC0 3 = 2K 2 Cr0 4 + 2C0 2 -f H 2 0. 

For analytical purposes solution of a neutral chromate is still 
more readily prepared by simply adding solution of ammonia to 
solution of red potassium chromate, until the liquid turns yellow, 
and, after stirring, smells of ammonia. 

K 2 Cr0 4 ,Cr0 3 + 2NH 4 HO = 2KNH 4 Cr6 4 + H 2 0. 

Other Analytical Reactions. — To a barium solution add a 
soluble carbonate (ammonium carbonate — (NH 4 ) 2 C0 3 — will 
generally be rather more useful than the others) ; a white pre- 
cipitate (barium carbonate, BaC0 3 ) results. To more of the 
solution add an alkaline phosphate or arseniate (sodium phos- 
phate — Na 2 HP0 4 — is the most common of these chemically 
analogous salts, but ammonium phosphate — (NH 4 ) 2 HP0 4 — or 
arseniate — (NH 4 ) 2 HAs0 4 — will subsequently have the pref- 
erence) ; white barium phosphate (BaHP0 4 ), insoluble in pure 
water, but slightly soluble in aqueous solutions of some salts, 
or barium arseniate (BaHAs0 4 ), both soluble even in acetic 
and other weak acids, will be precipitated. To another portion 
add ammonium oxalate (NH 4 ) 2 C 2 4 ; white barium oxalate 
(BaC 2 4 ) is precipitated, soluble in the diluted mineral acids 
and sparingly so in acetic acid. Barium salts moistened with 
hydrochloric acid impart a greenish color to flame. 

Mem. — Good practice will be found in writing out equations 
descriptive of each of the foregoing reactions. 



QUESTIONS AND EXEECISES. 

What is the quantivalence of barium ? — Write down the formulae of 
barium oxide, hydrate, chloride, nitrate, and sulphate, and state how 
they are prepared. — Describe the preparation of hydrogen peroxide. — 
Which of the tests for barium are most characteristic ? Give equations of 
the reactions. — Name the antidote in cases of poisoning by soluble barium 
salts, and explain its action. — How is hydrogen peroxide officially made? 



106 THE METALLIC KADICALS. 

CALCIUM. 

Symbol, Ca. Atomic weight, 40. 
Calcium compounds form a large proportion of the crust of our 
earth. Calcium carbonate is met with as chalk, marble, limestone, 
calc-spar, etc.; the sulphate as gypsum and plaster of Paris (Calcii 
Sulphas Uxsiccatus, U. S. P., " native sulphate of calcium — 
CaS0 4 ,2H 2 — rendered nearly anhydrous by heat") and alabaster ; 
the silicate in many minerals ; calcium fluoride as fluor-spar. The 
phosphate is also a common mineral. The element itself is only 
isolated with great difficulty. The atom of calcium is bivalent, 
Ca". 

Reactions having Synthetical Interest. 

Calcium Chloride, or Chloride of Calcium. 

First Synthetical Reaction. — To some hydrochloric acid add 
calcium carbonate (chalk, or the purer form, white marble, 
Marmor Album, B. P.) (CaC0 3 ) until effervescence ceases ; 
filter ; solution of calcium chloride (CaCl 2 ), the most common 
soluble salt of calcium, is formed. 

CaCO-3 + 2HC1 = CaCl 2 + H 2 + C0 2 

Calcium Hydrochloric Calcium Water. Carbonic 

carbonate. acid. chloride. acid gas. 

This solution contains carbonic acid, and will give a precipitate 
of calcium carbonate on the addition of lime-water. It may be 
obtained quite neutral by well boiling before filtering off the excess 
of marble. It is a serviceable test-liquid in analytical operations. 

Solution of calcium chloride evaporated to a syrupy consistence 
yields crystals (CaCl 2 ,6H 2 0). These are extremely deliquescent. 
The solution, evaporated to dryness, and the white residue heated 
to about 200° C, gives solid calcium chloride (CaCl 2 ,2H 2 0) in a 
porous form. The resulting agglutinated lumps ( Calcii Chloridum, 
U. S. P.) are used for drying gases and for freeing certain liquids 
from water. The salt is also soluble in alcohol. 1 part of this 
dried chloride with 10 of water forms the " Calcium Chloride Test- 
solution," U. S. P. 

Mem. — The practical student has already met with solution of 
calcium chloride as a by-product or secondary product in the prep- 
aration of carbonic acid gas. 

Marble often contains ferrous carbonate (FeC0 3 ), which in 
the above process becomes converted into ferrous chloride, 
rendering the calcium chloride impure : 



FeC0 3 


+ 2HC1 = 


FeCl 2 + H 2 


+ CO, 


Ferrous ■ 


Hydrochloric 


Ferrous Water. 


Carbonic 


carbonate. 


acid. 


chloride. 


acid gas. 



If absolutely pure calcium chloride be required, a few drops of 
the solution should be poured into a test-tube or test-glass, 
diluted with water, and examined for iron (by adding ammo- 



CALCIUM. 107 

nium sulphydrate. which gives a black precipitate with salts of 
iron), and, if the latter is present, calcium hypochlorite (in the 
form of chlorinated lime) and slaked lime be added to the 
remaining bulk of the liquid, and the whole boiled for a few 
minutes. Iron (as ferric hydrate) is thus precipitated ; on 
filtering a pure solution of calcium chloride is obtained : 

4FeCl 2 + Ca2C10 + 4CaH 2 2 4- 2H 2 = 2(Fe 2 6HO) + 5CaCl 2 

Ferrous Calcium Calcium Water. Ferric Calcium 

chloride, hypochlorite. hydrate. hydrate. chloride. 

This is the official process, and may be imitated on the small 
scale after adding a minute piece of iron to a fragment of the 
marble before dissolving in acid. 

The names, formulae, and reactions of the compounds of iron will 
be considered later. 

Calcium Oxide. 

Synonyms. — Oxide of Calcium ; Quick Lime ; Caustic Lime ; Lime. 

Second Synthetical Reaction. — Place a small piece of chalk 
in a strong grate fire or furnace, and heat until a trial frag- 
ment, chipped off and cooled, no longer effervesces on the addi- 
tion of acid ; caustic lime, CaO {Calx, U. S. P.), remains. 

CaCo 3 = CaO + C0 2 

Calcium Calcium Carbonic 

carbonate (chalk), oxide (lime). acid gas. 

Note. — Etymologically considered, this action is analytical {avalvu, 
analuo, I resolve), and not synthetical (avvdeacc, sunthesis, a putting 
together) ; but conventionally it is synthetical, and not analytical ; 
for in this, the usual sense, synthesis is the application of chemical 
action with the view of producing something ; analysis, the applica- 
tion of chemical action with the view of finding out the composition 
of a substance. In the etymological view of the matter there is 
scarcely an operation performed, either by the analyst or by the 
manufacturer, but includes both analysis and synthesis ; that is, 
includes interchange, or metathesis. 

Lime-kilns. — On a large scale the above operation is carried on in 
what are termed lime-kilns (kiln, Saxon cyln, from cylene, a furnace). 

Calcium Hydrate. 

Synonyms. — Hydrate of Calcium ; Slaked Lime ; Hydrate of 
Lime. 

Slaked Lime. — When cold, add to the lime about half its 
weight of water, and notice the evolution of steam and other 
evidence of strong action ; the product is slaked lime, hydrate 
of calcium (Ca2HO) ( Calcii Hydras, B. P.), the old hydrate 
of lime, with whatever slight natural impurities the lime may 



108 



THE METALLIC RADICALS. 



contain. The slaking of hard or " stony " lime may be accele- 
rated by using hot water. 

CaO + H 2 = Ca2HO 



Lime. 



Water. 



Calcium hydrate. 



Lime-water. — Place the calcium hydrate (washed with a 
little water to remove traces of soluble salts) in about a hun- 
dred times its weight of water ; in a short time a saturated 
solution, known as lime-water (Liquor Calais, U. S. P.), results. 
It contains about 0.15 per cent, of slaked lime, or about 16 
grains of calcium hydrate (Ca2HO), equivalent to about 11 or 
12 grains of lime (CaO) in 1 (Imperial) pint at 60° F.; at 
higher temperatures less is dissolved. Sp. gr. 1.0015. 

Strong Solution of Lime. — Slaked lime is more soluble in aqueous 
solution of glycerin and much more soluble in aqueous solution of 
sugar than in pure water. The Syrupus Colds', U. S. P., is such a 
solution, containing 6.5 parts of lime and 40 of sugar in 100 parts, 
by weight, of fluid. It is a more efficient precipitant of hydrates, 
carbonates, and phosphates than lime-water. The official (B. P.) 
process is as follows : Mix 1 ounce of lime and 2 of sugar by 
trituration in a mortar. Transfer the mixture to a bottle containing 
1 pint of water, and, having closed this with a cork, shake it occa- 
sionally for a few hours. Finally, separate the clear solution with 
a siphon, avoiding unnecessary exposure to air, and keep it in a 
well-stoppered bottle. 

Solutions of calcium hydrate absorb carbonic acid gas on exposure 
to air, a semi-crystalline precipitate of carbonate being deposited. 
When the saccharated solution is heated there is precipitated a com- 
pound consisting of three molecules of lime with one of sugar. 
When it is freely exposed to air, oxygen is absorbed and the solu- 
tion becomes colored. 



Calcium Carbonate. 

Synonyms. — Carbonate of Calcium ; Carbonate of Lime. 

Third Synthetical Reaction. — To a solution of calcium chloride 
add excess of sodium carbonate, or about 5 parts of dry chloride 
to 13 of carbonate ; a white precipitate of calcium carbonate 
(Calcii Carbonas Prsecipitatus, U. S. P., the old precipitated 
carbonate of lime) (CaC0 3 ) results. If the solutions of the 
salts be made hot before admixture and the whole be set aside 
for a short time, the particles aggregate to a greater extent 
than when cold water is used, and the product is finally 
granular or slightly crystalline. The official variety is thus 
prepared : 



CaCl 2 

Calcium 
chloride. 



= CaCO, 



2NaCl 



Sodium 
carbonate. 



Calcium Sodium 

carbonate. chloride. 



CALCIUM. 109 

Collect and purify this precipitated chalk by pouring the 
mixture into a paper cone supported by a funnel, and, when 
the liquid has passed through the filter, pour water over the 
precipitate three or four times, until the whole of the sodium 
chloride is washed away. This operation is termed loashing a 
precipitate. When dried by aid of a water-bath (p. 112) or 
other means the precipitate is fit for use. 

Fig. 22. 



Construction of Paper Filters. 

Filtering Paper, or Bibulous Paper (from bibo, I drink), is simply 
good unsized paper made from the best white rags — white blotting- 
paper, in fact, of unusually good quality. Students' or analysts' 
filters, on which to collect precipitates, are circular pieces (a, Fig. 
22) of this paper, from three to six inches in diameter, twice folded 
(6, c), and then opened out so as to form a hollow cone (d). Square 
pieces of filter-paper are rounded by scissors after twice folding. 
The cone is supported by a glass or earthenware funnel. 

Filters should always be cut round, so as to form a cone. If the 
square piece of paper is folded and used without being so cut or 
trimmed, an ugly angular filter results, from which it is difficult to 
wash all " mother-liquor " (the solution of sodium chloride is the 
"mother-liquor" in the previous reaction). Moreover, if a spirit- 
uous or other volatile fluid is being passed through such an angular 
filter, much of the liquor will also be wasted by evaporation from 
the unnecessarily large surface exposed. 

Paper filters of large size are apt to break at the point of the 
cone. This may be prevented and the rate of filtration be much 
accelerated by supporting the paper cone in a cone of muslin. 

Washing-bottle. — Precipitates are best washed by a fine jet of 
water directed on to the different parts of the filter. A common 
narrow-necked bottle, of about half-pint capacity (Fig, 23), is fitted 
with a cork ; two holes are bored through the cork, the one for a 
glass tube reaching to the bottom of the bottle within, and exter- 
nally bent to a slightly acute angle, the other for a tube bent to a 
slightly obtuse angle, the inner arm terminating just within the 
bottle. The outer arms may be about three inches in length. The 
extremity of the outer -arm continuous with the longer tube should 
be previously drawn out to a fine capillary opening by holding the 
original tube (before bending) in a flame, and, when soft, slowly 
pulling the halves away from each other until the heated portion is 
reduced to the thinness of a knitting-needle. The tube is now cut 
at the thin part by a file, and the sharp edges rounded off by placing 



110 



THE METALLIC RADICALS. 



in a flame for a second or two. The outer extremity of the shorter 
tube should also be made smooth in the flame. The apparatus being 



Fig. 23. 



Fig. 24. 





Washing-bottle. 



Washing-flask. 



put together and the bottle nearly filled with water, air blown through 
the short tube by the lungs forces water out in a fine stream at the 
capillary orifice. 

For a hot-water washing-flask (Fig. 24) the tubes and cork are 
fitted to a flask which may be heated. A strip of thin leather tied 
round the neck will protect the fingers. 

Decantation. — Precipitates may also be washed by allowing them 
to settle, pouring off the supernatant liquid (Fig. 25), agitating 



Fig. 25. 



Fig. 26. 



Fig. 27. 




Decantation. 



Decantation. 



Siphon in Action. 



with water, again allowing to settle, and so on. This is washing 
by decantation (de, from ; canthus, an edge). If a stream of liquid 
flowing from a basin or other vessel exhibits any tendency to run 
down the outer side of the vessel, it should be guided by a glass rod 
placed against the point whence the stream emerges (Fig. 26). 

If the vessel be too large to handle with convenience, the wash- 
water may be drawn off by a siphon, as shown in miniature in Fig. 
27. A siphon is a tube of glass, metal, gutta-percha, or india- 
rubber bent into the form of a V or U, filled with water and inverted. 



CALCIUM. Ill 

One end is immersed in the wash-water, and the other allowed to 
hang over the side of the vessel. So long as the outer orifice of the 
instrument is below the level of any liquid in the vessel, so long will 
that liquid flow from within outward.* 

Prepared calcium carbonate (Creta Pr&parata, U. S. P.) is merely 
washed chalk (Creta, B. P.) or ivhiting, only that in pharmacy fashion 
demands that the chalk be in little conical lumps, about the size of 
thimbles, instead of in the larger rolls characteristic of "whiting." 
Wet whiting pushed, portion by portion, through a funnel, and each 
separately dried, gives the conventional Creta Prozparata. Its powder 
is amorphous. 

If either the precipitated or the prepared calcium carbonate contains 
alumina, magnesian salts, iron oxides, or phospates, its solution in 
acid, evaporated and redissolved in water, will yield a precipitate of 
hydrates or phosphates on the addition of saccharated solution of lime. 

Calcium Phosphate. 

Synonyms. — Phosphate of Calcium 5 Phosphate of Lime ; Bone 
Phosphate. 

Fourth Synthetical Reaction. — Digest bone-ash (bones burnt 
in an open crucible with free access of air until all animal and 
carbonaceous matter has been removed — impure calcium phos- 
phate — Os Ustum, B. P.) with twice its weight of hydrochloric 
acid (diluted with four times its bulk of water) in a test-tube 
or larger vessel ; the phosphate is dissolved. 

Ca 3 2P0 4 -f 4HC1 = CaH 4 2P0 4 + 2CaCl 2 

Calcium Hydrochloric Acid Calcium 

phosphate acid. calcium chloride, 

(impure). phosphate. 

Dilute with water, boil, filter, and, when cold, add excess of 
solution of ammonia ; the calcium phosphate, now practically 
pure (Calcii Phosphas Prdecipitatus, U. S. P.), the old phosphate 
of lime, is reprecipitated as a light white amorphous powder. 
After well washing the precipitate should be dried over a water- 
bath (see next page) or at a temperature not exceeding 212° F., 
to prevent undue aggregation of the particles. 

CaH 4 2P0 4 + 2CaCl 2 + 4NH 4 HO = Ca 3 2P0 4 + 4NH 4 C1 + 4H. 2 

Acid Calcium Ammonia. Calcium Ammonium Water, 

calcium chloride. phosphate chloride, 

phosphate. (pure). 

* The nature of the action of a siphon is simple. The column of water 
in the outer limb is longer, and therefore heavier, than the column of 
similar area in the inner limb. (The length of the inner limb must be 
reckoned from the surface of the liquid, the portion below the surface 
playing no part in the operation.) Being heavier, it naturally falls by 
gravitation, the liquid in the shorter limb instantly following because 
pressed upward by the air. The air, be it observed, exerts a similar 
amount of pressure on the liquid in the outer limb ; in short, atmo- 
spheric pressure causes the retention of liquid in the instrument, while 
gravitation determines the direction of the flow. 



112 THE METALLIC RADICALS. 

Bone-ash or bone-earth contains small quantities of calcium 
carbonate and sulphide. These are decomposed in the above 
process by the acid, calcium chloride being formed ; on boiling 
the mixture, carbonic acid gas and sulphuretted hydrogen gas 
are evolved. Any carbonaceous or siliceous matter, etc. is 
removed by nitration. In bones the calcium phosphate is 
always accompanied by a small quantity of an allied sub- 
stance, magnesium phosphate : a trace of calcium fluoride 
(CaF 2 ) is also present. 

A water-bath for the evaporation of liquids or for drying moist 
solids at temperatures below 212° F. is an iron, tin, or earthenware 
pan, the mouth of which can be narrowed by iron or tin diaphragms 
of various sizes, and having orifices adapted to the diameters of 
basins or plates. (See Fig. 16, p. 71.) In the British Pharmacopoeia, 
" when a ivater-bath is directed to be used it is to be understood 
that this term refers to an apparatus by means of which water or 
its vapor, at a temperature not exceeding 212°, is applied to the 
outer surface of a vessel containing the substance to be heated, 
which substance may thus be subjected to a heat near to, but neces- 
sarily below, that of 212°. In the steam-bath the vapor of water at 
a temperature above 212°, but not exceeding 230°, is similarly 
applied." Evaporation in vacuo is performed by simply placing 
the vessel of liquid over or by the side of a small reservoir of 
strong sulphuric acid or other absorbent of moisture, on the plate 
of an air-pump, covering with a capacious glass hood or " receiver," 
and exhausting. 

Bone-black, or Animal Charcoal ( Carbo Animalis, U. S. P.), 
is the residue obtained on subjecting dried bones to a red heat 
without access of air. It is a mixture of about 9 parts of 
mineral matter with 1 of carbonaceous matter. The opera- 
tion may be imitated by heating a few fragments of bone in a 
covered porcelain crucible in a fume-chamber until smoke and 
vapor cease to be evolved. Purified animal charcoal (Carbo 
Animalis Purificatus, U. S. P.) may be obtained as follows : 
Boil powdered animal charcoal with a mixture of twice its 
weight of hydrochloric acid and twice its weight of water ; 
filter ; again boil the drained residue with half the amount of 
such diluted acid as was previously employed ; again filter ; 
wash the residual charcoal with distilled water until the wash- 
ings give little or no turbidity with solution of silver nitrate ; 
dry the product in a warm place. It should not yield more 
than 10 per cent, of moisture when dried at a high temperature, 
nor more than 15 per cent, of ash when thoroughly incinerated. 
Thirty grains well shaken with fifteen ounces of distilled water 
containing 0.005 per cent, of ordinary commercial caramel 



CALCIUM. 113 

should remove at least four-fifths of the color from the fluid 
(Hodgkin). 

Wood Charcoal ( Carbo Ligni ) U. S. P.) is wood similarly 
ignited without access of air. On incineration it yields about 
2 per cent, of ash. 

Decolorizing Power of Animal Charcoal. — Animal charcoal, 
in small fragments, is the material employed in decolorizing 
solutions of common brown sugar with the view of producing 
white lump sugar. Its power, and the nearly equal power of 
an equivalent quantity of the purified variety, may be demon- 
strated on solution of litmus or logwood. 

Syrup of calcium lacto-phosphate (Syrupus Calcii Lacto- 
phosphatis, U. S. P.) is a flavored solution of precipitated cal- 
cium phosphate in lactic acid. 

Sodium Phosphate. — Calcium phosphate is converted into 
sodium phosphate (Sodii Phosphas, U. S. P., the old phosphate 
of soda) (Na 2 HP0 4 ,12H 2 0), as follows: Mix, in a mortar, 300 
grms. of ground bone-earth with 100 cc. of sulphuric acid ; 
set aside for twenty-four hours to promote reaction ; mix in 
about 300 cc. of water, and put in a warm place for two days, 
a little water being added to make up for that lost by evapor- 
ation ; stir in another 300 cc. of water, warm the whole for a 
short time, filter, and wash the residual calcium sulphate on the 
filter to remove adhering acid calcium phosphate ; concentrate 
the filtrate (the liquid portion), which is a solution of acid cal- 
cium phosphate, to about 300 cc. ; filter again if necessary, add 
solution of (about -150 grms. of crystals of) sodium carbonate 
to the hot filtrate until a precipitate (a calcium phosphate, 
CaHP0 4 ) ceases to form, and the liquid is faintly alkaline ; 
filter, evaporate, and set aside to crystallize. 

Sodium phosphate occurs " in transparent, colorless, rhombic 
prisms, terminated by four converging planes ; efflorescent, 
tasting like common salt." 1 part in 10 of water constitutes 
" Solution of Phosphate of Sodium," B. P. The following 
equations show the two decompositions which occur during the 
operations : 

Ca 3 2P0 4 + 2H 2 S0 4 = CaH 4 2P0 4 + 2CaS0 4 

Calcium Sulphuric Acid calcium Calcium 

phosphate. acid. phosphate. sulphate. 

CaH 4 2P0 4 + Na 2 C0 3 = Na 2 HP0 4 + H 2 + C0 2 + CaHP0 4 

Acid calcium Sodium Sodium Water. Carbonic Monocalcic 

phosphate. carbonate. phosphate. acid gas. phosphate. 

Ordinary sodium phosphate (Na 2 HP0 4 ,12H 2 0) effloresces 
rapidly in the air until nearly half its water has escaped, when 
it has a permanent composition represented by the formula 



114 THE METALLIC RADICALS. 

Na 2 HP0 4 ,7H 2 0. Sodium phosphate has an alkaline reaction. 
Neutralization by acid results in the removal of half its sodium 
and formation of the salt NaH 2 P0 4 ,H 2 0. 

Calcium Hypochlorite, or Hypochlorite of Calcium. 

Fifth Synthetical Reaction. — Pass chlorine, generated as 
already described, into damped slaked lime contained in a piece 
of wide tubing, open at the opposite end to that in which the 
delivery-tube is fixed. (A test-tube, the bottom of which has 
been accidentally broken, is very convenient for such operations.) 
The product is ordinary bleaching-powder, a compound of cal- 
cium hypochlorite and chloride, commonly called chloride of lime 
or chlorinated lime, the Calx Chlorata of the United States 
Pharmacopoeia. 



Mn0 2 -f 4HC1 = 

k. manganese Hydrochloric 
oxide. acid. 


Mn€l 2 + 2H 2 + Cl 2 
Manganese Water. Chlorine, 
chloride. 

Chlorinated lime. 


2CaH 2 2 + 2C1 2 == 
Calcium Chlorine, 
hydrate. 


2H 2 -f CaCl 2 2 , CaCl 2 

Water. Calcium Calcium 
hypochlorite, chloride. 



Chlorinated lime exposed to air and moisture, as in disinfect- 
ing the atmosphere of sick-rooms, slowly yields hypochlorous 
acid (HCIO). Free hypochlorous acid soon breaks up into 
water, chloric acid (HC10) 3 , and free chlorine. Chloric acid is 
also unstable, decomposing into oxygen, chlorine, water, and 
perchloric acid (HC10 4 ). The small quantity of hypochlorous 
acid diffused through an apartment when bleaching-powder is 
exposed thus yields fourteen-fifteenths of its chlorine in the 
form of chlorine gas — one of the most efficient of known dis- 
infectants. 

Constitution of Bleaching-powder. — Treated with alcohol, bleach- 
ing-powder does not yield its calcium chloride to the solvent ; hence 
the powder is not a mere mixture of calcium chloride and hypo- 
chlorite ; water, also, does not dissolve out first one salt and then 
the other, but both together, in the molecular proportions of the 
above formula. On the other hand, when the aqueous solution is 
cooled, or evaporated in vacuo, crystals are obtained which Kingzett 
has shown to be nearly pure calcium hypochlorite, the solution con- 
taining calcium chloride. While the former fact indicates that the 
powder is a compound, and not a mere mixture, the latter indicates 
that it is a feeble compound — an adhesion of molecules of hypo- 
chlorite and chloride, as shown in the equation, rather than any 
more intimate or closer combinations of atoms. If it be regarded as 
a single rather than a double salt, then the following formula may 
be employed : 

CaOCl 2 , or Ca j ^ 



CALCIUM. 115 

Bleaching -liquor. — Digest chlorinated lime in water, in which 
the bleaching compound is soluble, filter from undissolved lime, 
etc., and test the bleaching powers of the clear liquid by adding 
a few drops to a decoction of logwood slightly acidulated. 1 
pound of this bleaching-powder, shaken several times during 
three hours with 1 gallon of water, forms the official solution 
of chlorinated lime (Liquor Calcis Chlorinatse, B. P.). 

Sixth Synthetical Reaction. — Heat to a bright redness a mix- 
ture of 17 parts of powdered dried calcium sulphate and 9 of 
charcoal in a crucible having a luted cover until the contents 
are no longer black. Some of the sulphate is reduced to 
calcium sulphide, with production of carbon oxides. The 
product, when cold, rubbed to powder, constitutes sulphurated 
lime (Calx Sulphurata, U. S. P.). It should contain not less 
than 60 per cent, of pure cajcium sulphide (CaS) ; the re- 
mainder is sulphate, with, probably, calcium sulphite and hypo- 
sulphite. 

Official Tests of Strength. — " If 1 grm. of sulphurated lime 
be gradually added to a boiling solution of 2.08 gnus, of cupric 
sulphate in 50 cc. of water, the mixture digested on a water- 
bath for fifteen minutes, and filtered when cold, no color should 
be imparted to the filtrate by one drop of potassium ferro- 
cyanide." — U. S. P. 

The B. P. test is similar — eight grains of the substance and 
fourteen of copper sulphate with a little acid, and warmed 
as above. 

The explanation of the mode of action of the B. P. test is as fol- 
lows : Copper sulphate and calcium sulphide, in the presence of the 
acid, react on each other, giving insoluble copper sulphide and cal- 
cium sulphate, thus : 

CuSo„5H 2 + CaS = CuS -f- CaS0 4 ,2H 2 -f 3H 2 0. 

On adding up the atomic weights of the constituent elements of 
crystallized copper sulphate, 249.5 will be found to be the molecular 
weight, while CaS will similarly represent 72 parts. As 249.5 are 
to 72, so are 14 to 4. But only half of the sulphurated lime is cal- 
cium sulphide ; 8 grains of such sulphurated lime will react with 14 
of copper sulphate. If the 8 grains are below the stated strength, 
then they will not attack 14 grains of copper salt, and in that case 
potassium ferrocyanide will reveal copper in the filtered liquid. 

Calcium Sulphate. 

Synonyms.— Plaster of Paris ; Gypsum (CaSOJ ; Sulphate of 
Lime. 

It is found native, and the dried substance is now official, Calcii 
Sulphas Exsiccatus, U. S. P. It should contain about 95 per cent. 



116 THE METALLIC RADICALS. 

of anhydrous calcium sulphate, and then it occurs in a fine white 
amorphous powder, void of odor and taste, very slightly soluble in 
water, soluble in dilute nitric and hydrochloric acids, and in satu- 
rated solutions of potassium nitrate, sodium hyposulphite, and other 
ammonium salts; insoluble in alcohol. Calcium sulphate, when 
mixed with half its weight of water and made into a paste, rapidly 
hardens. 

Solution of Calcium Sulphate. — A \ ounce of that (dried) form of 
sulphate of calcium known as plaster of Paris (CaSOJ digested in 
1 pint of water for a short time, with occasional shaking, and the 
mixture filtered, yields the official test-liquid termed " Solution of 
Sulphate of Calcium," B. P. About 400 parts of the solution con- 
tain 1 of calcium sulphate. 

Calcium Gummate. 

Calcium Gummate is the only official calcium salt that re- 
mains to be noticed. This compound is, in short, arabin, the 
ordinary gum-acacia or gum-arabic ( Acacise, U. S. P.), a sub- 
stance too well known to need description. A solution of 
gum-arabic in water {Mucilago Acacisz, U. S. P.) yields a white 
precipitate of calcium oxalate on the addition of solution of 
ammonium oxalate. Or a piece of gum burnt to an ash in a 
porcelain crucible yields a calcareous residue, which, dissolved 
in dilute acids, affords characteristic reactions with any of the 
following analytical reagents for calcium. In some specimens 
of gum-arabic a portion of the calcium is displaced by an equiv- 
alent quantity of potassium or magnesium. The gummic or 
arabic radical may be precipitated as opaque gelatinous lead 
gummate by the addition of solution of lead oxyacetate {Liquor 
Plumbi Subacetatis, U. S. P.) to an aqueous solution of gum. 
These statements should be experimentally verified. 

Tragacanth (Tragacantha, U. S. P.) is a mixture of soluble arabi- 
noid gum and a variety of calcium gum insoluble in water, termed 
bassorin. With water a gelatinous mucilage is formed [Mucilago 
Tragacanthce, U. S. P.) containing 6 parts of tragacanth, 18 of 
glycerin, and 76 of water. 

Reactions having Analytical Interest (Tests). 

First Analytical Reaction. — Add sulphuric acid, very highly 
diluted, to a calcium solution contained in a test-tube or small 
test-glass ; calcium sulphate (CaS0 4 ,2H 2 0) is formed, but is 
not precipitated, it being, unlike barium sulphate, slightly sol- 
uble in water. 

Second Analytical Reaction. — Add yellow potassium chromate 
(K 2 Cr0 4 ) or other neutral chromate (KNH 4 Cr0 4 ) to a calcium 



CALCIUM. 117 

solution slightly acidified with acetic acid ; calcium chromate 
(CaCr0 4 ) may be formed, but is not precipitated. Barium is 
precipitated by the chromate. 

These two negative reactions are most valuable in analysis, as 
every precipitant of calcium is also a precipitant of barium, but the 
above two reagents are precipitants of barium only. Hence, calcium, 
which when alone can be readily detected by the following reactions, 
cannot by any reaction be detected in the presence of barium. But 
by the sulphuric or chromic test barium is easily removed, and then 
either of the following reagents will throw down the calcium. 

Other Analytical Reactions. — Add ammonium carbonate, 
sodium phosphate, ammonium arseniate, and ammonium 
oxalate to calcium solutions, as described under the analyt- 
ical reactions of barium, and write out descriptive equations. 
The precipitates correspond in appearance to those of barium ; 
their constitution is also similar, hence their correct formulae 
can easily be deduced. Of these precipitants, ammonium oxa- 
late is that most commonly used as a reagent for calcium salts, 
barium being absent. The calcium oxalate is insoluble in 
acetic, but soluble in hydrochloric or nitric, acid. Calcium 
compounds impart a reddish color to flame. 



QUESTIONS AND EXEECISES. 



Enumerate some of the common natural compounds of calcium. — 
Explain by an equation the action of hydrochloric acid on marble. 
Wbat official compound results? — Why is calcium chloride used as a 
desiccator for gases ? — How would you purify calcium chloride which 
has been made from ferruginous marble ? Give diagrams. — Write a few 
lines on the chemistry of the lime-kiln. — In what sense is the conversion 
of chalk into lime an analytical action ? — What occurs when lime is 
" slaked " ? — To what extent is lime soluble in water? to what in syrup? 
— Describe the preparation of the official precipitated calcium carbon- 
ate ; in what does it differ from prepared chalk? — In what does filter- 
ing-paper differ from other kinds of paper ? — Explain the construction 
of a " washing-bottle " for cleansing precipitates by water. — Define decan- 
tation. — Describe the construction and manner of employment of a siphon. 
— Explain the mode of action of a siphon. — State the difference between 
Os Ustum and Calcii Phosphas. — How is " bone-earth " purified for use in 
medicine? — Explain the action of hydrochloric acid on animal charcoal 
in the processes of purification. — What is the chemical difference between 
Carbo Animalis, U. S. P., and Carbo Ligni, U. S. P. ? — Give equations show- 
ing the conversion of calcium phosphate into sodium phosphate. — Write 
a short article on the manufacture, composition, and uses of " bleaching- 
powder." — How may calcium be detected in gum-arabic? — State the 
chemical nature of tragacanth. — To what extent is calcium sulphate 
soluble in water? — Can calcium be detected in a solution containing 
barium ? — Barium being absent, what reagents may be used for the detec- 
tion of calcium? Which is the chief test? 
6* 



118 THE METALLIC RADICALS. 

MAGNESIUM. 

Symbol, Mg. Atomic weight, 24. 

Source. — Magnesium is abundant in nature as magnesian or 
mountain limestone, termed dolomite (after Dolomieu, a geologist), 
a double magnesium and calcium carbonate in very common use as 
a building-stone (e. g. the Houses of Parliament and School of Mines 
in London), and magnesite, a tolerably pure magnesium carbonate, 
though too "stony" for direct use in medicine, even if very finely 
powdered. Magnesium chloride and magnesium sulphate (Epsom 
salt) also occur in sea-water and the water of many springs. A 
monohydrous sulphate (MgS0 4 ,H 2 0), termed kieserite, occurs near 
Stassfurt in Prussia. Metallic magnesium may be obtained from 
the chloride by the action of sodium. It burns readily in the air, 
emitting a dazzling light, due to the white heat to which the result- 
ing particles of magnesia (MgO) are exposed. The chloride employed 
as a source of the metal is obtained by dissolving the carbonate in 
hydrochloric acid, adding some ammonium chloride, evaporating to 
dryness, heating the residue in a deep vessel (on the small scale, a 
large test-tube or flask) until the ammonium chloride is all volatilized, 
and the magnesium chloride remains as a clear fused liquid. The 
latter is poured on to a clean earthenware slab. The ammonium 
chloride prevents reaction between magnesium chloride and water 
in the last stages of the operation, and consequent formation of 
magnesium oxide (or oxychloride) and hydrochloric acid gas. 

Quantivalence. — The atom of magnesium is bivalent, Mg". 

Reactions having Synthetical Interest. 
Magnesium Sulphate. 

Synonyms. — Sulphate of Magnesium; Sulphate of Magnesia; 
Epsom Salt. 

First Synthetical Reaction. — To a few drops of sulphuric 
acid and a little water in a test-tube, made hot (or to larger 
quantities in larger vessels), add powdered native magnesium 
carbonate, magnesite, MgC0 3 , until effervescence ceases, sub- 
sequently boiling to aid in the expulsion of the carbonic acid 
gas. The filtered liquid is a solution of magnesium sulphate 
(MgS0 4 ), crystals of which, Epsom salt (MgS0 4 ,7H 2 0) (Mag- 
nesii Sulphas, U. S. P., the old sulphate of magnesia), may be 
obtained on evaporating most of the water and setting the 
concentrated solution aside to cool. This is an ordinary man- 
ufacturing process. Instead of magnesite dolomite, the com- 
mon magnesian limestone (magnesium and calcium carbonate 
— CaC0 3 ,MgC0 3 ), may be employed, any iron being removed 
by evaporating the solution (filtered from the calcium sulphate 
produced) to dryness, gently igniting to decompose the ferrous 
sulphate, dissolving in water, filtering from iron oxide, and 



MAGNESIUM. 119 

crystallizing. (If neither mineral be at hand, the practical 
student may use a little of the ordinary manufactured car- 
bonate of pharmacy, for the chemical action is almost identical, 
and it is the chemistry, and not, just now, the commercial 
economy of the matter, that he is studying. The manufacturer 
must, of course, commence with one of the above mineral car- 
bonates furnished by Nature, from that make his sulphate, 
and from the latter, as will be seen directly, make the pure 
pulverulent carbonate of pharmacy.) 

MgC0 3 -f H 2 SO, = MgS0 4 + H 2 + C0 2 

" Magnesite." Sulphuric Magnesium Water. Carbonic 

acid. sulphate. acid gas. 

Magnesium sulphate readily crystallizes in large, colorless, trans- 
parent, rhombic prisms, but from concentrated solutions the crystals 
are deposited in short, thin needles, a form more convenient for 
manipulation, solution, and general use in medicine. 

Iron may be detected in magnesium sulphate by adding the com- 
mon alkaline solution of chlorinated lime or chlorinated soda to 
some aqueous solution of the salt ; brown ferric hydrate (Fe 2 6HO) 
is then precipitated. Ammonium sulphydrate will also give a black 
precipitate if iron be present. 

Effervescent Sulphate of Magnesium (Magnesii Sulphas Efferves- 
cens, B. P.) is magnesium sulphate out of which nearly half its 
water of crystallization has been dried, and then mixed with citric 
and tartaric acids and sugar. 

Magnesium Carbonates. 

Synonyms. — Carbonates of Magnesium ; Carbonates of Magnesia. 

Second Synthetical Reaction. — To solution of magnesium 
sulphate add solution of sodium carbonate, and boil ; the result- 
ing precipitate is light magnesium carbonate {Magnesii Carbo- 
nas Levis, B. P., Magnesii Carbonas, U. S. P.), the old light 
carbonate of magnesia, a white, partly amorphous, partly 
minutety crystalline mixture of magnesium carbonate and 
hydrate (3MgC0 3 ,Mg2HO,4H 2 0). A denser, slightly granular 
precipitate of similar chemical composition (Magnesii Carbonas 
Ponderosa, B. P.), the old heavy carbonate of magnesia, is 
obtained on mixing strong solutions of the above salts, evaporat- 
ing to dryness, then removing the sodium sulphate by digest- 
ing the residue in hot water, filtering, washing, and drying the 
precipitate. 

4MgSO, -f 4Na 2 C0 3 + H 2 = 3MgC0 3 ,Mg2HO + 4Na ? S0 4 + C0 2 

Magnesium Sodium Water. Official magnesium Sodium Carbonic 

sulphate. carbonate. carbonate. sulphate, acid gas. 

The official (B. P.) proportions for the light carbonate are 10 of 
magnesium sulphate and 12 of crystals of sodium carbonate, each 



120 THE METALLIC RADICALS. 

dissolved in 80 of cold water, the solutions mixed, boiled for fifteen 
minutes, the precipitate collected on a filter, well washed, drained, 
and dried over a water-bath. The heavier carbonate is made with 
the same proportions of salts, each dissolved in 20 instead of 80 of 
water, the mixture evaporated quite to dryness, and the residue 
washed by decantation or filtration until all sodium sulphate is 
removed (shown by a white precipitate — barium sulphate — ceasing 
to form on the addition of solution of barium chloride or nitrate to a 
little of the filtrate). 

Another {PatUnson 1 s) Process. — Considerable quantities of mag- 
nesium carbonate are now prepared by treating dolomite (p. 118) 
with carbonic acid gas under pressure. Of the two carbonates, that 
of magnesium is dissolved first, and is precipitated from the clear 
liquid by the heat of a current of steam. (See next reaction.) 

Tliird Syyitlietical Reaction. — Pass carbonic acid gas, generated 
as described on page 72, into a mixture of water and magne- 
sium carbonate contained in a test-tube. After some time 
separate any undissolved carbonate by filtration ; the filtrate 
contains normal magnesium carbonate (MgC0 3 ,3H 2 0) dissolved 
in carbonic acid. When of a strength of about 10 grains of 
official carbonate in 1 ounce, such a solution constitutes " Fluid 
Magnesia " (Liquor Magnesii Carbonatis, B. P.). It is possible 
to obtain a strength of about 3 per cent, at about 55° F., which 
is reduced to 2 J per cent, at 70° and to about 2 per cent, at 
80°. 

Officially, 1 pint is directed (B. P.) to be made from freshly-pre- 
pared carbonate. The latter is obtained by adding a hot solution 
of 2 ounces of magnesium sulphate in J pint of water to one of 2£ 
ounces of crystals of sodium carbonate in another \ pint of water, 
boiling the mixture for a short time (to complete decomposition), 
filtering, thoroughly washing the precipitate, placing the latter in 
1 pint of distilled water, and transmitting carbonic acid gas through 
the liquid (say, at the rate of three or four bubbles per second) for 
an hour or two, then leaving the solution in contact with the gas 
under pressure' of about three atmospheres for twenty-four hours, and, 
finally, filtering from undissolved carbonate; then, after passing in 
a little more gas, keeping in a well-corked bottle. Slight pressure is 
best produced by placing the carbonate and water in a bottle fitted 
with a cork and tubes as for a wash-bottle (p. 97), conveying the 
gas by the tube which reaches to the bottom, and allowing excess of 
gas to flow out by the upper tube, the external end of which is con- 
tinued to the bottom of a common phial containing about an inch 
of mercury. The phial should be loosely plugged with cotton wool, 
to prevent loss of metal by spurting during the flow of the gas 
through it. (Each inch in depth of mercury through which the gas 
escapes corresponds to about \ pound pressure on every square inch 
of surface within the apparatus.) 

Heat a portion of the solution : true magnesium carbonate con- 



MAGNESIUM. 121 

taining combined water (MgC0 3 ,3H 2 0) is precipitated. The water 
in this compound is probably in the state of water of crystallization, 
for a salt having the same composition is deposited in crystals by the 
spontaneous evaporation of the solution of magnesium carbonate. The 
official "carbonate" (3MgC0 3 ,Mg2HO,4H 2 b) is another of these 
very common hydrous compounds. 

Exposed to cold, the solution of "fluid magnesia" sometimes 
affords large thick crystals (MgC0 3 ,5H 2 0), which, in contact with 
the air, lose water, become opaque, and then have the composition 
of those deposited by evaporation (MgC0 3 ,3H 2 0). 

It is difficult to understand the constitution of the official carbon- 
ate. It is probably a single molecule, of the constitution of which 
we are at present ignorant. 

Magnesium Oxide. 

Synonyms. — Oxide of Magnesium ; Magnesia ; Calcined Magnesia. 

Fourth Synthetical Reaction. — Heat light dry magnesium 
carbonate in a porcelain crucible over a lamp (or in a larger 
earthen crucible in a furnace) till it ceases to effervesce on add- 
ing water and acid to a small portion ; the residue is light 
magnesia (MgO) (Magnesia Levis, B. P., Magnesia, U. S. P.). 
The same operation on the heavy carbonate yields heavy 
magnesia (MgO) (Magnesia Ponderosa, U. S. P.). Both are 
sometimes spoken of as " calcined magnesia." A given weight 
of the official light magnesia occupies three and a half times 
the bulk of the same weight of heavy magnesia. 

3MgC0 3 ,Mg2HO = 4MgO + H 2 + 3C0 2 

Official magnesium Magnesium Water. Carbonic 

carbonate. oxide. acid gas. 

A trace only of magnesia is dissolved by water. Moisten 
a grain or two of magnesia with water, and place the paste on a 
piece of red litmus-paper ; the wet spot after a time becomes 
blue, showing that the magnesia is slightly soluble. 

" Effervescing Citrate of Magnesia" so called, is generally a mix- 
ture of sodium bicarbonate, citric acid, tartaric acid, sugar, either 
magnesium carbonate or sulphate, or both, and flavoring essences. 
True magnesium citrate is easily made by combining together 
calcined magnesia and citric acid ; it is frequently prescribed in 
France in doses of 2 ounces. 

The "Granulated Citrate of Magnesium " (Magnesii Citras Effer- 
vescens, U. S. P., Effervescent Magnesium Citrate) is made as fol- 
lows: Mix 10 parts of "magnesium carbonate intimately with 30 of 
citric acid, and enough distilled water to make a thick paste ; dry 
this at a temperature not exceeding 30° C. (86° F.), and reduce it to 
a fine powder. Then mix it intimately with 8 of sugar (No. 60 
powder), 34 of sodium bicarbonate, and 16 of citric acid previously 
reduced to a very fine powder. Dampen the mass with a sufficient 



122 THE METALLIC RADICALS. 

quantity of alcohol, arid rub it through a No. 20 tinned-iron sieve to 
form a coarse, granular powder. Lastly dry it in a moderately 
warm place. 

The official effervescing " Solution of Magnesium Citrate " 
{Liquor Magnesii Citratis, U. S. P.) is made by dissolving magne- 
sium carbonate in slight excess of solution of citric acid, adding 
lemon syrup, placing the diluted liquid in an aerated-water bottle, 
dropping in crystals of potassium bicarbonide, corking at once, 
" wiring," and shaking till the crystals are dissolved. 

The formula of magnesium citrate deposited from solution is 
Mg 3 2C 6 H 5 7 ,i4H 2 0. 

Reactions having Analytical Interest (Tests). 

First Analytical Reaction. — Add solution of ammonium 
hydrate or carbonate to a magnesium solution (sulphate, for 
example), and warm the mixture in a test-tube ; the precipita- 
tion of part only of the magnesium as hydrate (Mg2HO) or 
carbonate (MgC0 3 ) occurs. Add now to a small portion of 
the mixture of precipitate and liquid a considerable excess of 
solution of ammonium chloride ; the precipitate is dissolved. 

This is an important reaction, especially as regards magnesium 
carbonate, the presence of ammonium chloride enabling the analyst 
to throw out from a solution barium and calcium by an alkaline 
carbonate, magnesium being retained. The cause of this retention 
is found in the tendency of magnesium to form soluble double salts 
with potassium, sodium, or ammonium. In analysis the ammo- 
nium chloride should be added before the carbonate, as it is easier to 
prevent precipitation than to redissolve a precipitate once formed. 

Second Analytical Reaction. — To some of the solution result- 
ing from the last reaction add solution of sodium or ammo- 
nium phosphate ; a white granular precipitate (magnesium and 

ammonium phosphate, MgNH 4 P0 4 ) results. Third. — To 

another portion add ammonium arseniate ; a precipitate similar 
in appearance falls (magnesium and ammonium arseniate, 
MgNH 4 As0 4 ). 

Note. — Barium and calcium are also precipitated by alkaline 
phosphates and arseniates. The other precipitants of magnesium 
are also precipitants of barium and calcium. In other words, there 
is no direct test for magnesium. Hence the analyst always removes 
any barium or calcium by an alkaline carbonate, as above indicated ; 
the sodium phosphate (or ammonium arseniate or phosphate) then 
becomes a very delicate test of the presence of magnesium. In 
speaking of magnesium tests, the absence of barium and calcium 
salts is to be understood. 



QUESTIONS AND EXERCISES. 
Name the natural sources of the various salts of magnesium. — Give a 
process for the preparation of Epsom salt. — Draw diagrams illustrative 



MAGNESIUM. 



123 



of the formation of magnesium sulphate from magnesite and from dolomite. 
Show by an equation the process for the preparation of the official mag- 
nesium carbonate. — What circumstances determine the two different 
states of aggregation of the official magnesium carbonates {Magnesii 
Carbonas Ponderosa, B. P., and Magnesii Carbonas Levis, U. S. P.) ? — Whatare 
the relations of Magnesia Ponderosa, B. P., and Magnesia Levis, B. P., to the 
official magnesium carbonates ? — How much denser is the one than the 
other? — Is magnesia soluble in water? — How is " Fluid Magnesia " pre- 
pared? — Mention the effects of heat and cold on "Fluid Magnesia." — 
Ascertain how much magnesia (MgO) can be obtained from 100 grains 
of Epsom salt. — Calculate the amount of official magnesium carbonate 
which will yield 100 grains of magnesia. — Can magnesium be detected in 
presence of barium and calcium ? — Describe the analysis of an aqueous 
liquid containing salts of barium, calcium, and magnesium. — How may 
magnesium be precipitated from solutions containing ammoniacal salts ? 



Quantivalence, or Valency. 
On reviewing the foregoing statements regarding compounds of 
the three univalent radicals — potassium, sodium, and ammonium — 
and the three bivalent elements — barium, calcium, and magnesium — 
the doctrine of quantivalence, or valency, will be more clearly 
understood and its usefulness be more apparent. Quantivalence, or 
the value of atoms, is, in short, in chemistry, closely allied to value in 
commercial barter. A number of articles, differing much in weight, 
appearance, and general characters, may be of equal money value ; 
and if these be regarded, for convenience, as having a sort of unit 
of value, others worth double as much might be termed bivalent, 
three times as much trivalent, and so on. In like manner, chemical 
radicals, no matter whether elementary, like potassium (K), iodine 
(I), or sulphur (S), or compound, like those of nitrates (N0 3 ), sul- 
phates (S0 4 ), or acetates (C 2 H 3 2 ), have a given chemical value in 
relation to each other, and are exchangeable for, or will unite with, 
each other to an extent determined by that value. Two such radi- 
cals may be considered to be present in a molecule of most ordinary 
salts, a basylous and an acidulous radical, one quantivalently bal- 
ancing the other. The formulae of the chief of these radicals and 
their quantivalence are given in the following table. Examples of 
formulas of salts containing univalent, bivalent, and trivalent radi- 
cals are given in the succeeding table : 

Quantivalence op Common Radicals. 



Univalent Radicals, 


Bivalent Radicals, 


Trivalent Radicals, 


or 


Monads. 


or Dyads. 


or Triads. 


Acidulous. 


Basylous. 


Acidulous. Basylous. 


Acidulous. Basylous. 


H 


H 


Ca 


P0 4 As 


CI 


K 


S0 4 Mg 


B0 3 Sb 


I 


Na 


C0 3 Zn 


C 6 H 5 7 Bi 


HO 


NH, 


C 2 4 Cu 


As0 3 f Fe m (ic) 


N0 3 


Ag 


C*H 4 6 Hg(ic) 


As0 4 \ or 


C 2 H 3 2 


Hg(ous) 


S Fe(ous) 


C 4 H 3 5 I Fe^Cic) 



124 THE METALLIC RADICALS. 

Note 1. — Hydrogen (H) as the basylous part of salts has entirely 
different functions to hydrogen (H) as the acidulous part. Acidulous 
hydrogen gives compounds commonly termed hydrides {e.g. AsH 3 ) ; 
basylous hydrogen is the basylous radical of acids {e.g. HC1,- 
H 2 S0 4 ). On the other hand, in compound radicals, e. g. C 2 H 3 2 or 
NH 4 , these properties of hydrogen are no longer apparent; the 
chemical force resident with the atoms of such radicals seems to be 
mainly exerted in binding those atoms together. 

Note 2. — The name, symbol, quanti valence, and atomic weight of 
all the important elements are given in a table immediately preced- 
ing the Index. 

Examples of Formulas of Salts containing Univalent, Bivalent, and 
Trivalent Radicals. 

The reader will find instructive practice in writing twenty or 
thirty imaginary formulas of salts by placing in juxtaposition acidu- 
lous and basylous radicals, as in the following table of examples. 
Just as in a pair of scales a 2-lb. weight must be balanced by two 
1-lb. weights, or a 4-lb. weight by two 2-lb. weights, or by one 34b. 
and one 1-lb. weight, so a bivalent radical unites with a bivalent 
radical or with two univalent radicals, a quadrivalent radical with 
two bivalent radicals, or with one trivalent and one univalent 
radical, and so on. 

(R = any basylous radical. R = any acidulous radical.) 

General Formulae. Examples. 

WR' . . . KI, NaCl, NH 4 C 2 H 3 2 , AgN0 3 . 

R"^ . . CaCl 2 , Zn2C 2 H $ 2 , Pb2N0 3 (BaN0 3 C 2 H 3 2 ). 

W"R\ . . Bi3N0 3 , AsH 3 , SbCl 3 . 

R' 2 i2" . 1 f K 2 C0 3 , Na 2 S0 4 , H 2 C 4 H 4 6 . 

WWR" . J J KHC0 3 , NaHS0 4 , KNaC 4 H 4 6 . 

W S B'" . \ f (NH 4 ) 3 P0 4 , K 3 C 6 H 5 7 , H 3 As0 3 . 

B,' 2 WR"' j J Na 2 HP0 4 , Na 2 HAs0 4 . 

WR" . . CaC0 3 , MgO, CuS0 4 , HgO, FeS0 4 . 

W\R"\ . Ca 3 2P0 4 , Ca 3 2C 6 H 5 7 . 

R"R'J2'" . MgNH 4 P0 4 , CuHAs0 3 . 

W"R"R' . BiON0 3 . 

R'" 2 R" 2 R" Bi 2 2 C0 3 . 

W" 2 R" 3 . As 2 3 , Sb 2 3 , Fe 2 3 , Fe 2 3S0 4 . 

W"R'" . . BiC 6 H 5 O r 

W" 2 R' 6 . . Pe 2 Cl 6 , Fe 2 6N0 3 , Fe 2 6C 2 H 3 2 . 

Quadrivalent Radicals or Tetrads, Quinquivalent Radicals or 
Pentads, and Sexivalent Radicals or Hexads, are known. 

Cautions. — 1. The student will not mistake valency for strength. 
Bivalent atoms, for example, will vary as much in 'power of chem- 
ical attachment as several two-armed boys will vary from each other 
in power of grasp. The greater the quantivalence of an atom, the 
more compounds it will form ; the stability of those compounds is 
another affair altogether. Indeed, it often happens that the greater 
the complexity, the less the stability of a molecule. 2. A " radical " 



MAGNESIUM. 125 

is a single or whole substance in a broad and general sense only, the 
great majority of radicals themselves admitting of subdivision. A 
molecule, like a crystal, is only broadly a whole or single thing, 
open to attack or cleavage from without, and probably then will 
split in more than one or two directions. 

Exercise. — Write an exposition of the doctrine of quantivalence 
within the limits of a sheet of note-paper. 



DIRECTIONS FOR APPLYING THE FOREGOING ANALYTICAL REAC- 
TIONS TO THE ANALYSIS OF AN AQUEOUS SOLUTION* OF 
A SALT OF ONE OF THE METALS, BARIUM, CALCIUM, MAG- 
NESIUM. 

Add yellow potassium chromate to a portion of the solution 
to be examined ; a precipitate indicates barium. 

If no barium is present, add ammonium chloride and carbon- 
ate, and boil ; a precipitate indicates calcium. 

If barium and calcium are proved to be absent, add ammo- 
nium chloride, ammonia, and then either sodium phosphate or 
ammonium arseniate ; a white granular precipitate indicates 
magnesium. 

Ammonia is here added to yield the necessary elements to am- 
monio-magnesian phosphate or ammonio-magnesian arseniate, both 
of which are highly characteristic precipitates ; and ammonium 
chloride is added to prevent a mere partial precipitation of the 
magnesium by the ammonia. 



DIRECTIONS FOR APPLYING THE FOREGOING ANALYTICAL REAC- 
TIONS TO THE ANALYSIS OF AN AQUEOUS SOLUTION OF 
SALTS OF ONE, TWO, OR ALL THREE OF THE METALS, 
BARIUM, CALCIUM, MAGNESIUM. 

Add potassium chromate to the solution ; barium, if present, 
is precipitated. Filter, if necessary, and add to the filtrate 
(that is, the liquid which has run through the filter) ammonium 
chloride, hydrate, and carbonate, and boil ; calcium, if present, 
is precipitated. Filter, if requisite, and add sodium phosphate ; 
magnesium, if present, is precipitated. 

Note. — Red potassium chromate must not be used in these ope- 
rations, or a portion of the barium will remain in the liquid and be 
thrown down with, or in the place of, the calcium carbonate. ( Vide 
p. 105). The yellow chromate must not contain potassium carbonate, 

* In preparing such solutions for analysis, salts should be selected 
which do not decompose each other. Chlorides will serve in most cases, 
but nitrates and acetates are still more convenient. 



126 



THE METALLIC RADICALS. 



or calcium will be precipitated with, or in the place of, barium. The 
absence of carbonate is proved by the non-occurrence of efferves- 
cence on the addition of hydrochloric acid to a little of the solution 
of the chromate, previously made hot in a test-tube. If the yellow 
chromate has been prepared by adding excess of ammonia to solu- 
tion of red potassium chromate, its addition to the liquid to be 
analyzed must be preceded by that of solution of ammonium 
chloride ; the precipitation of a portion of the magnesium (by the 
free ammonia in the yellow chromate) is thus prevented ; for solu- 
tion of ammonium chloride is a good solvent of magnesium hydrate 
(and carbonate), as already stated on page 122. 



TABLE OF SHORT DIRECTIONS FOR APPLYING THE FOREGOING 
ANALYTICAL REACTIONS TO THE ANALYSIS OF AN AQUEOUS 
SOLUTION OF SALTS CONTAINING ANY OR ALL OF THE 
METALLIC ELEMENTS HITHERTO CONSIDERED. 

To the solution add NH 4 C1,NH 4 H0,(NH 4 ) 2 C0 3 ; boil and filter. 



Precipitate 


Filtrate 


BaCa. 


MgNH 4 NaK. 


Wash, dissolve in HC 2 H 3 2 , 


Acid (NH 4 ) 2 HP0 4 , shake, filter. 


add K 2 Cr0 4 , and filter. 




Precipitate 


Filtrate 


Precipitate 


Filtrate 


Ba* 


Ca. 


Mg. 


NH 4 Na K. 




Test by 




Evap. to dryness, ignite, 




(NH 4 ) 2 C 2 4 . 




dissolve residue in 

water. 
Test for K by PtCl 4 . 
" " Naby flame. 
Test orig. sol. for NH 4 . 



Note 1. — The analysis of solutions containing the foregoing 
metals is commenced by the addition of ammonium chloride (NH 4 C1) 
and ammonia (NH 4 HO), simply as a precautionary measure, the 



* It is perhaps scarcely necessary to state that this precipitate is not 
barium (Ba) itself, but barium chromate (BaCrO-O, asany reader who has 
carefully gone through the " foregoing analytical reactions " will know. 
Chemical symbols and formulse are often used for mere shorthand pur- 
poses, but no intelligent student will thereby be misled. The occurrence 
of barium chromate here, however, and under the circumstances 
described, is abundant evidence of the presence of barium (Ba, in some 
form or other) in the liquid analyzed ; which was a part of the problem 
to be solved by the operator. Similar remarks apply to the Ca, which is 
finally precipitated as oxalate (CaCzO*), to Mg, which is thrown out as 
ammonio-phosphate (MgNH4PC>4), to NIL, Na, and K, and to the ele- 
ments similarly alluded to in the other subsequent tables of "short" 
directions for analysis. 



MAGNESIUM. 127 

former compound preventing partial precipitation of magnesium, the 
latter neutralizing acids. The ammonium carbonate, (NII 4 ) 2 C0 3 , is the 
important group-reagent — the precipitant of barium and calcium. 

Note 2. — In the above and in subsequent charts of analytical pro- 
cesses the leading precipitants will be found to be ammonium salts. 
These being volatile, can be got rid of toward the end of the opera- 
tions, and thus the detection of potassium and sodium be in no way 
prevented — an advantage which could not be had if such salts as 
potassium chromate or sodium phosphate were the group precipi- 
tants employed. 

Note 3. — Acetic, and not hydrochloric or nitric, acid is used in 
dissolving the barium and calcium carbonates, because barium 
chromate — on the precipitation of which the detection of barium 
depends — is soluble in the stronger acids, and therefore could not be 
thrown down in their presence. 

Note on Classification. — The compounds of barium, calcium, and 
magnesium, like those of the alkali metals, have many analogies ; 
the carbonate, phosphate, and arseniate of each are insoluble in 
water, which sufficiently distinguishes them from the members of 
the class first studied. They possess, however, well-marked differ- 
ences, so that their separation from each other is easy. The solu- 
bility of their hydrates in water marks their connection with the 
alkali metals ; the slightness of that solubility, diminishing as we 
advance farther and farther from the alkalies, baryta being most 
and magnesia least soluble in water, points to their connection with 
the next class of metals, the hydrates of which are insoluble in 
water. These considerations must not, however, be overvalued. 
Though the solubility of their hydrates places barium nearest and 
magnesium farthest from the alkali metals, the solubility of their 
sulphates gives them the opposite order, magnesium sulphate being 
most soluble, calcium sulphate next, strontium sulphate third 
(strontium is a rarer element, mentioned subsequently), while 
barium sulphate is insoluble in water. These elements are some- 
times spoken of as the metals of the alkaline earths. 

Note.— In connection with the bivalence of the atoms of barium, 
calcium, and magnesium, it is interesting to note that just as biva- 
lent acidulous radicals give salts containing two atoms of univalent 
basylous radicals (K 2 S0 4 ,H 2 C0 3 ,KNaC 4 II 4 6 ), so bivalent basylous 
radicals yield salts containing two atoms of univalent acidulous 
radicals, as seen in acetonitrate of barium, BaC 2 II 3 2 N0 3 , a salt 
which is a definite compound, and not a mixture of acetate with 
nitrate. A large number of such salts is known. 

Distillation. 
The water with which, in analysis, solution of a salt or dilution 
of a liquid is effected should be pure. Well and river-waters are 
unfit for the purpose, because they contain alkaline and earthy salts 
(some 20 to 60 grains per gallon), derived from the soil through 
which the water percolates, and rain-water is not infrequently con- 
taminated^ with the dust and debris which fall on the roofs whence* 
it is usually collected. Such water is purified by distillation, an 



128 



THE METALLIC RADICALS. 



operation in which the water is, by ebullition, converted into steam, 
and the steam condensed again to water in a separate vessel, the 
fixed earthy and other salts remaining in the vessel in which the 
water is boiled. On the large scale ebullition is effected in metal 
boilers having a hood or head in which is a wide lateral channel 

Fig. 28. 




Distillation, on a Small Scale. 

through which passes the steam ; on the small scale either a common 
glass flask is employed, into the neck of which, by a cork, is inserted 
a glass tube bent to an acute angle, or a retort is used (a, Fig. 28), a 
sort of long-necked Florence flask, dextrously bent near the body 
by the glass-worker to an appropriate angle (hence the name retort, 
from retorqueo, I bend back). Condensation is effected by surround- 
ing the lateral steam-tube with cold water. In large stills the 
steam-tube, or condensing worm, is usually a metal (tin) pipe, 
twisted into a spiral form for the sake of compactness, and so fixed 
in a tub that a few inches of one end of the pipe may pass through 
and closely fit a hole bored near the bottom of the tub. Cold water 
is kept in contact with the exterior of the pipe, provision being 
made for a continuous supply to the bottom, while the lighter 
water, heated by the condensing steam, runs off from the top of the 
column. The condenser for a flask or retort may be a simple glass 
tube of any size placed within a much wider tube (a common long, 
narrow lamp-glass answers very well for experimental operations), 
the inner tube being connected at the extremities of the wider by 
bored corks ; a stream of water passes into one end of the enclosed 
space (the end farthest from the retort), through a small glass tube 
inserted in the cork, and out at the other end through a similar tube. 
The common (Liebig's) form of laboratory condenser is a glass tube 
three-fourths of an inch wide and a yard long (6, Fig. 28), sur- 
rounded by a shorter tin or zinc tube (c, Fig. 28) two inches in 
diameter, and having at each extremity a neck, through which the 
glass tube passes. The ends of the necks of the tin tube and small 
portions of the glass tube near them are connected by means of a 
strip of sheet caoutchouc carefully bound round, or by short wide 
^ndia-rubber tubes (d and e, Fig. 28). An aperture (/, Fig. 28) 
near the lower part of the tin tube provides for the admission of a 



MAGNESIUM. 129 

current of cold water, by glass tubing or india-rubber tubing, from 
the house supply or from a vessel placed above the apparatus ; and 
a similar aperture near the top (g, Fig. 28) allows the escape of 
heated water into a vessel or sink. The inner tube may thus con- 
stantly be surrounded by cold water, and heated vapors passing 
through it be perfectly cooled and condensed, and collected in any 
receiver (h, Fig. 28). 

In distilling several gallons of water for analytical or medicinal 
purposes {Aqua Destillata, IT. S. P.) the first two or three pints 
should be rejected, because they are likely to contain ammoniacal 
and other volatile impurities. 

Water (Aqua, B. P.) is defined as natural water, the purest that 
can be obtained, cleared, if necessary, by filtration ; free from odor, 
unusual taste, and visible impurity. The official "water" (Aqua, 
U. S. P.) is not to contain more than 1 part in 2000 of soluble salts, 
and to be so free from organic matter that when tinted rose-red with 
potassium permanganate the color should not be destroyed after 
boiling the fluid for five minutes, or, in the case of distilled water, 
after setting the vessel aside, well covered, for ten hours. In dis- 
pensing prescriptions aqua should be understood to mean distilled 
water. 

Rectification is the process of redistilling a distilled liquid. Rec- 
tified spirit is spirit of wine which has thus been treated. 

Dry or destructive distillation is distillation in which the condensed 
products are directly formed by the decomposing influence of the 
heat applied to the dry or non-volatile substances in the retort or 
still. 

Exercise. — Write from memory a short description of distillation. 



Kecapitulatory. 



The subject just alluded to (distillation) naturally causes wonder 
respecting the cause of the physical differences between solid, liquid, 
and gaseous water. Common observation will have suggested to 
the student that the force of heat has much to do with the differ- 
ences ; and if he will turn to the chapter on latent heat in any book 
on Physics, he will find that, as already indicated (p. 86), when ice 
liquefies by heat a very large amount of heat must be given before 
the slightest rise of temperature occurs. Afterward the addition of 
heat makes the water hotter and hotter, until one other point is 
reached (the boiling-point), when here again a great amount of 
heat is absorbed without causing the slightest rise of temperature. 
Afterward more heat makes the gaseous water hotter and hotter, 
until, like a bar of iron, the steam, under special conditions, is 
made red hot or even white hot. Different bodies absorb different 
amounts of heat in changing their physical condition from solid to 
liquid or liquid to gas (or vapor). The amount is constant for any 
one body ; hence definite comparative numbers may be used for 
expressing the latent heats of substances. 



130 



THE METALLIC RADICALS. 



The absorption of heat at particular (liquefying and vaporizing) 
points must not be confounded with an analogous physical action — 
namely, the absorption of heat which goes on when a body is rising 
in temperature. The amount of this absorption, also, differs with 
different substances. That is to say, if equal weights of several 
substances, all at the same temperature, be heated to a stated 
higher temperature, very different amounts of fuel will be required. 
The particular or specific amount in each case is always the same ; 
hence the specific heats of substances may be expressed by numbers. 
See the chapter on " Specific Heat" in any manual of Physics. 

But after reading what has been stated respecting the constitution 
of matter (pp. 42 to 46), the chemical student will, in connection 
with the subject of distillation, be led once more to think over the 
subject of molecular constitution of solid, liquid, and gaseous water, 
and of the molecular condition of bodies generally. As previously 
stated, little can be told him respecting the molecular condition of 
solids and liquids, for temperature and pressure affect them 
unequally ; whence we conclude that though the relation to each 
other of the molecules of any one substance is constant, this rela- 
tion is different in different bodies. Different gases, however, are 
not differently affected, but similarly affected, by temperature and 
pressure ; whence we conclude that their molecular constitution— 
the relation of their molecules to one another — is similar. 

Another gas, ammonia, has been brought before the reader since 
the molecular constitution of gases was considered. 

A small quantity of ammonia gas enclosed in the upper part of 
a roughly graduated test-tube over mercury (water would dissolve 
it), and exposed to the continuous action of the electric spark by 
means of wires of platinum fused in the sides of the tube, is decom- 
posed into its elements, nitrogen and hydrogen, the bulk of gas 
operated on being exactly doubled. This expansion is not due to 
the gaseous molecules receding from each other, but to every two 
molecules becoming four similar-sized molecules : 



N 




N 


H 




H 


H 




H 


H 




H 



N 




H 




H 




H 


N 




H 




H 




H 



Here each space (rectangular chiefly for convenience in printing) 
represents a molecule and each letter an atom. Each space, if 
regarded as the side of a double cube, may also, for the moment, 
represent two volumes, such two volumes yielding, in the decompo- 
sition, one volume of nitrogen and three volumes of hydrogen, or 
the four such double-cube volumes of ammonia shown in the dia- 
gram yielding two volumes of nitrogen and six volumes of hydrogen. 

Kemembering that a symbol (of a gas) represents one volume, 
and that a formula (of a gas) always represents two volumes, the 
pupil will now see how full of meaning is such an equation as the 
following, including, as it does, names of the elements, number of 
atoms, nature of the molecules, number of the molecules, weights 



ZINC. 131 

of atoms of the molecules, and therefore weights of bulks of the 
bodies, or extent of expansion in the disunion of the elements, and 
therefore their extent of contraction in the act of union : 

2NH 3 = N 2 -f- 3H 2 . 

At this stage the learner is again recommended to 
read the paragraphs on the greneral principles of 
Chemical Philosophy (pages 35-57), and to return 
to them from time to time until they are thoroughly 
comprehended. 



ZINC, ALUMINIUM, IRON. 

These three elements are classed together for analytical con- 
venience rather than for more general analogies. 

ZINC. 

Symbol, Zn. Atomic weight, 64.9. 

Source. — Zinc is tolerably abundant in Nature as sulphide (ZnS) 
or blende, and carbonate (ZnC0 3 ) or calamine (from calamus, a reed, 
in allusion to the appearance of the mineral). The ores are roasted 
to expel sulphur, carbonic acid gas, and some impurities, and 
the resulting oxide heated with charcoal, when the metal vapor- 
izes and readily condenses. Zinc is a brittle metal, but at a tem- 
perature somewhat below 300° F. is malleable and may be rolled 
into thin sheets. Above 400° it is again brittle, and may then be 
pulverized. At 773° F. it melts, and at a bright red heat is volatile. 
Zinc in exceptionally fine powder ignites spontaneously, especially 
if damp or if stored in a warm place. 

Uses. — Its use as a metal is familiar : alloyed with nickel, it 
yields German silver ; with twice its weight of copper it forms 
common brass, and as a coating on iron (the so-called galvanized 
iron) greatly retards the formation of rust. Most of the salts of 
zinc are prepared, directly or indirectly, from the metal (Zincum, 

Quantivalence. — The atom of zinc is bivalent, Zn". 
Molecular Weights. — Some remarks on this point will be made 
under Mercury. 

Reactions having Synthetical Interest. 

Zinc Sulphate, or Sulphate of Zinc. 

First Synthetical Reaction. — Heat zinc (4 parts) with water 
(20 parts) and sulphuric acid (3 fluid parts) in a test-tube (or 
larger vessel) until gas ceases to be evolved ; solution of zinc 
sulphate results. Filter (to separate the particles of lead, 
carbon, etc. present in common zinc) and concentrate the solu- 



132 THE METALLIC RADICALS. 

tion in an evaporating-dish ; on cooling, colorless, prismatic 
crystals of zinc sulphate (ZnS0 4 ,7H 2 0) are deposited (Zinci 
Sulphas, U. S. P.). 

Zn 2 + 2H 2 S0 4 + *H 2 = 2ZnS0 4 + 2H 2 + zH 2 
Zinc. Sulphuric acid. Water. Zinc sulphate. Hydrogen. Water. 

Ordinary zinc does not displace hydrogen from pure sulphuric 
acid alone nor from pure water alone, yet it does from the mixture. 
The possible explanation is that as sulphuric acid combines with 
several different quantities of water to form definite hydrous com- 
pounds (H 2 S0 4 ,H 2 5 H 2 S0 4 ,2H 2 ; etc.), it is one or more of these 
that is decomposed with elimination of hydrogen. At present we 
can only say that an unknown (x) amount of water is required in 
the reaction. 

Note. — This reaction affords hydrogen and zinc sulphate ; it also 
develops electricity. Of several methods of evolving hydrogen it is 
the most convenient ; of the two or three means of preparing zinc 
sulphate it is that most commonly employed ; and of the many 
reactions which may be utilized in the development of voltaic elec- 
tricity it is one of the most convenient. The apparatus in which 
the reaction is effected differs according to the requirements of the 
operator : if the zinc sulphate alone is wanted, an open dish is all 
that is necessary, the action being, perhaps, accelerated by heat ; 
if hydrogen, a closed vessel and delivery-tube ; if electricity, certain 
vessels called cells and various complementary materials, forming 
altogether what is termed a battery. In each operation for one of 
the three the other two are commonly wasted. It would not be 
difficult for the operator, as a matter of amusement, to construct an 
apparatus from which all three should be collected. 

Purification. — Impure zinc sulphate may be purified in the same 
manner as impure chloride. (See next Reaction.) 

Zinc sulphate is isomorphous with magnesium sulphate, and, like 
that salt, loses six-sevenths of its water of crystallization at 100° C. 
An old name for it is white vitriol (p. 144). 

Zinc Chloride, or Chloride of Zinc. 

Second Synthetical Reaction. — Digest zinc in hydrochloric 
acid mixed with half its bulk of water ; the resulting solution 
contains zinc chloride. Evaporate the liquid till no more steam 
escapes ; zinc chloride (ZnCl 2 ) in a state of fusion remains, 
and, on cooling, is obtained as an opaque white solid (Zinci 
Chloridum, U. S. P.). It is soluble in water, alcohol, or ether. 

Zn 2 + 4HC1 = 2ZnCl 2 + 2H 2 
Zinc. Hydrochloric acid. Zinc chloride. Hydrogen. 

This reaction is analogous to that previously described. Burnett's 
deodorizing or disinfecting liquid is solution of zinc chloride. 

Purification of Zinc Chloride or Sulphate. — Zinc sometimes con- 
tains traces of iron or lead, and these, like zinc, are dissolved by 
most acids, with formation of soluble salts; they may be recognized 



zinc. 133 

in the liquids by applying the test described hereafter (p. 136) to a 
little of the solution in a test-tube. Should either be present in the 
above solution, a little chlorine-water is added to the liquid till the 
odor of chlorine is permanent, and then the whole well shaken with 
some zinc hydrate or the common official zinc "carbonate" (really 
hydrato-car bonate ; see next page). In this way iron is precipitated 
as ferric hydrate, and lead as peroxide : 

*2FeCl 2 + Cl ? = *Fe 2 Cl 6 

Ferrous chloride. Chlorine. Ferric chloride. 

Fe 2 Cl 6 -f 3ZnH 2 2 = Fe 2 6HO = 3ZnCl 2 

Ferric chloride. Zinc hydrate. Ferric hydrate. Zinc chloride. 

PbCl 2 -f Cl 2 -f 2ZnH 2 2 = Pb0 2 -f 2ZnCl 2 + 2H 2 

Lead Chlorine. Zinc Lead Zinc Water, 

chloride. hydrate. peroxide. chloride. 

In the British Pharmacopoeia the possible presence of impurities 
in the zinc is recognized, and the process of purification just de- 
scribed incorporated with the process of preparation of Zinci 
Chloridum, Liquor Zinci Chloridi, and Zinci Sulphas. In the 
purification of the zinc sulphate the action of chlorine on any fer- 
rous sulphate will result in the formation of ferric sulphate as well 
as ferric chloride : 

6FeS0 4 + 3C1 2 = 2(Fe 2 3S0 4 ) + Fe 2 Cl 6 . 

Zinc carbonate will then give chloride as well as zinc sulphate, and 
thus the whole quantity of zinc sulphate be slightly contaminated 
by chloride. On evaporating and crystallizing, however, the zinc 
chloride will be retained in the mother-liquor. These processes of 
purification admit of general application. 

For Liquor Zinci Chloridi, B. P., 1 pound of zinc is placed in a 
mixture of 44 fluidounces of hydrochloric acid and 20 of water, the 
mixture ultimately warmed until no more gas escapes, filtered into 
a bottle, chlorine-water added until the liquid, after shaking, smells 
fairly of chlorine, about ^ an ounce or somewhat more of zinc car- 
bonate shaken up with the solution until a brown precipitate of ferric 
hydrate or lead peroxide, or both, appears, the whole filtered, and 
the filtrate evaporated to 40 fluidounces. 1 fluidounce contains 366 
grains of zinc chloride. If, on testing a little of the solution first 
produced with ammonia and ammonium sulphydrate, the precipitate 
is quite white, neither iron nor lead was present in the zinc, and the 
treatment with chlorine-water and zinc carbonate is to be omitted. 

The solution of zinc chloride (Liquor Zinci Chloridi, U.- S. P.) is 
prepared by a somewhat similar process ; nitrie acid, however, is 
used instead of chlorine-water ; the solution contains " about 50 per 
cent, of the salt (ZnCl 2 )," sp. gr. about 1.535. It is miscible with 
alcohol in all proportions, indicating absence of basic chloride of 
zinc. 

* It will be noticed that the atom of iron is represented, in these 
equations, as exerting both bivalent and trivalent activity ; this will be 
alluded to when iron comes under consideration. 

7 



134 THE METALLIC KADICALS. 

Zinc Bromide, ZnBr 2 (Zinci Bromidum, U. S. P.), may be made 
by the action of zinc on hydrobromic acid and evaporation to dry- 
ness. It is a white powder, but may be sublimed in needles. 

Zinc Iodide, Znl 2 [Zinci Iodidum, U. S. P.), may be made from 
its elements. It is a white powder, but when volatilized condenses 
in acicular prisms. 

Carbonate of Zinc, or Zinc Carbonate. 

Third Synthetical Reaction. — To solution of any given quan- 
tity of zinc sulphate in twice its weight of water (in a test-tube, 
evaporating-basin, or other large or small vessel) add about an 
equal quantity of sodium carbonate, also dissolved in twice its 
weight of water, and boil ; the resulting white precipitate is so- 
called zinc carbonate (Zinci Carbonas, B. P., Zinci Carbonas 
Prsecipitatus, U. S. P.), or precipitated zinc carbonate, a mixture 
of carbonate (ZnC0 3 ) and hydrate (Zn2HO) in the proportion 
of one molecule of the former and two of the latter, together 
with a molecule of water (H 2 0) ; these proportions, however, 
vary considerably. It may be washed, drained, and dried in 
the usual manner. It is used in the arts under the name of 
zinc-white. 

3ZnS0 4 +2H 2 0+3Na 2 CO s =ZnC0 3 ,2ZnH 2 2 +2C0 2 + 3Na 2 SO, 

Zinc Water. Sodium Official zinc Carbonic Sodium 

sulphate. carbonate. carbonate. acid gas. sulphate. 

Calamina Prceparata, B. P., is a smooth, pale pinkish-brown 
powder, obtained by calcining and powdering native zinc carbonate 
or calamine, and freeing the product from gritty particles by elutri- 
ation. Prepared calamine is chiefly zinc carbonate with some iron 
oxide, etc. 

Elutriation (Lat. elutriatus ; elutreo ; eluo ; I wash out). — This 
fractional operation consists in straining off water (or other liquids — 
light like ether, or heavy like chloroform) containing lighter par- 
ticles in suspension from heavier and coarser particles which have 
become deposited. The decanted fluid yields a sediment of the fine 
particles on standing. By allowing a varying number of seconds to 
elapse between the shaking and the decantation, and by the use of 
fluids of different specific gravities and different degrees of limpidity 
or viscidity, substances of different specific gravities or particles of 
different; degrees of fineness of any one substance may be separated 
from each other. 

Zinc Acetate, or Acetate of Zinc. 

Fourth Synthetical Reaction. — Collect on a filter the precipi- 
tate obtained in the last reaction, wash with distilled water, and 
dissolve a portion in strong acetic acid ; the resulting solution 
contains zinc acetate, and on evaporating and setting aside 



zinc. 135 

yields lamellar pearly crystals (Zn2C 2 H 3 2 ,2H 2 0), Zinci Acetas, 
U. S. P. 

ZnCO ? ,2ZnHA+6HC 2 H 8 O a = 3(Zn2C,H s O0 + 5H 2 + CO, 

Official zinc carbonate. Acetic acid. Zinc acetate. Water. Carbonic 

acid gas. 

Zinc Oxide, or Oxide of Zinc. 

Fifth Synthetical Reaction. — Dry the remainder of the pre- 
cipitated carbonate (by placing the open filter on a plate over 
a dish of water kept boiling), and then heat it in a small cruci- 
ble till trial samples taken out of the crucible from time to 
time cease to effervesce on the addition of water and acid ; the 
product is zinc oxide (Zinci Oxidum, U. S. P), much used in 
the form of ointment ( Unguentum Zinci Oxidi, U. S. P.). 

ZnCO ? ,2ZnH 2 2 = 3ZnO + 2H 2 + CO, 

Official zinc carbonate. Zinc oxide. Water. Carbonic acid gas. 

Note. — This oxide is yellow while hot, and of a very pale yellow 
or slight buff tint when cold — not actually white, like the oxide pre- 
pared by the combustion of zinc in air. The preparation of the 
latter variety, which also occurs in commerce, can only be practically 
accomplished on the large scale ; but the chief features of the action 
may be observed by heating a piece of zinc on charcoal in the blow- 
Fig. 29. Fig. 30. 




The Blowpipe. 

pipe flame (Fig. 29) till it burns ; flocks escape, float about in the 
air, and slowly fall. These are the old Flores Zinci, Lana Philo- 
sophical, or Nihilum Album. 

A clear blowpipe flame consists more or less of two portions (see 
Fig. 30) — an inner cone, at the apex of which are hot hydrocarbon 
gases greedy of oxygen, and an outer cone, at the apex of which is 
excess of hot oxygen. At the latter point oxidizable metals, etc. 
are readily oxidized, as in the foregoing experiment, and that part 
of the flame is therefore termed the oxidizing flame ; in the inner 
flame oxides and other compounds (a grain of lead acetate may be 



136 THE METALLIC RADICALS. 

employed for illustration) are reduced to the metallic state ; hence 
that part is termed the reducing flame. A blowpipe flame is much 
altered in character by slight variations in the position of the nozzle 
of the blowpipe, by the form of the nozzle, by the force with which 
air is expelled from the blowpipe, and by the character of the jet 
of gas. 

Zinc oxide slowly absorbs carbonic acid from moist air, and is 
partly reconverted into the hydrato-carbonate. 

Zinc Valerianate, or Valerianate of Zinc. 

Sixth Synthetical Reaction. — The zinc valerianate (Zn2C 5 H 9 
2 ,H 2 0), Zinci Valerianas, U. S. P., is prepared by mixing 
strong solutions of zinc sulphide and sodium valerianate, cooling, 
separating the white pearly crystalline substance, evaporating 
at 200° F. to a low bulk, cooling, again separating the lamellar 
crystals, washing the whole product with a small quantity of 
cold distilled water, draining, and drying by exposure to air at 
ordinary temperatures. Zinc valerianate is soluble in ether, 
alcohol, or hot water. 

ZnS0 4 + 2NaC 5 H 9 2 = Na 2 SO, -f- Zn2C 5 H 9 2 
Zinc sulphate. Sodium valerianate. Sodium sulphate. Zinc valerianate. 

Other Zinc Compounds. 

Oleatum Zinci, U. S. P., is a zinc soap or zinc oleate dis- 
solved in a considerable excess of oleic acid. It is prepared by 
dissolving 5 parts of zinc oxide in 95 of oleic acid. 

Zinc Sulphide and Hydrate are mentioned in the follow- 
ing analytical paragraphs. The formula of zinc sulphite is 
ZnS0 3 ,3H 2 0. 

Reactions having Analytical Interest (Tests). 
First Analytical Reaction. — To solution of a zinc salt (sul- 
phate, e. g.) in a test-tube add solution of ammonium sul- 
phydrate (NH 4 HS) ; a white precipitate (zinc sulphide, ZnS) 
falls, insoluble in acetic acid, soluble in the stronger acids. 

Note. — This is the only white sulphite that will be met with. Its 
formation, on the addition of the ammonium sulphydrate, is there- 
fore highly characteristic of zinc. If the zinc salt contains iron or 
lead as impurities, the precipitate will have a dark appearance, the 
sulphides of those metals being black. Aluminium hydrate, which 
is also white and precipitated by ammonium sulphydrate, is the only 
substance for which zinc sulphide is likely to be mistaken, and vice 
versa ; but, as will be seen immediately, there are good means of 
distinguishing these from each other. 

Second Analytical Reaction. — To solution of a zinc salt add 
ammonia ; a white precipitate (zinc hydrate, Zn2HO) appears. 



ALUMINIUM. 137 

Add excess of ammonia ; the precipitate is redissolved. This 
reaction at once distinguishes a zinc salt from an aluminium 
salt, aluminium hydrate being insoluble in dilute ammonia. 

Other Analytical Reactions. — The fixed alkali-hydrates afford 
a similar reaction to that just mentioned, zinc hydrate redis- 
solving if the alkali is free from carbonate. Ammonium carbo- 
nate yields a white precipitate of carbonate and hydrate, soluble 
in excess. The fixed alkaline carbonates give a similar precipi- 
tate, which is not redissolved if the mixed solution and precipi- 
tate be well boiled. Potassium ferrocyanide precipitates white 
zinc ferrocyanide (Zn 2 FeCy 6 ). 

Magnesium sulphate, which is isomorphous with, and some- 
times indistinguishable in appearance from, zinc sulphate, is not 
precipitated from its solutions either by potassium ferrocyanide 
or ammonium sulphydrate. 

Antidotes. — There are no efficient chemical means of counter- 
acting the poisonous effects of zinc, Large doses, fortunately, 
act as powerful emetics. If vomiting has not occurred or 
apparently to an insufficient extent, solution of sodium carbon- 
ate (common washing soda), immediately followed by white 
of egg and demulcents, may be administered, and then the 
stomach be cleared. 



QUESTIONS AND EXEECISES. 

Give the sources and uses of metallic zinc. — Give a diagram of the 
action of zinc on diluted sulphuric acid. — How may solutions of zinc 
chloride or sulphate be purified from salts of iron ? Give equations for 
the reactions. — State the formula of the official zinc carbonate, and illus- 
trate by a diagram the reaction which takes place in its production. — 
Give an equation for the synthesis of zinc acetate. — In what respect 
does zinc oxide, resulting from the ignition of the carbonate, differ from 
that produced during the combustion of the metal ? — How is zinc valerian- 
ate prepared? — What are the properties of zinc valerianate ? — Name the 
more important tests for zinc. — How would you distinguish, chemically, 
between solutions of zinc sulphate and alum ? — Describe the treatment 
in cases of poisoning by zinc salts. — Give reactions distinguishing zinc 
sulphate from magnesium sulphate. 



ALUMINIUM, OR ALUMINUM. 

Symbol, Al. Atomic weight, 27. 

Note on Nomenclature^ — The author prefers the spelling aluminium,, 
as giving a more euphonious word than aluminum. In the 
United States Pharmacopoeia the second i is omitted both in the 
English and the Latin names. 

Note on Quantivalence. — In the formulae of aluminium salts it will 
be observed that to one atom of metal there are three atoms of other 



138 THE METALLIC RADICALS. 

univalent radicals ; hence, apparently, the atom of aluminium is 
trivalent, Al /// . But possibly it is quadrivalent, for one molecule 
of aluminium compounds includes two atoms of the metal, three- 
fourths only of whose power may be supposed to be exerted in 
retaining the other constituents of the molecule, the remaining 
fourth enabling the aluminium atoms themselves to keep together. 
This is graphically shown in the following formula of aluminium 
chloride (A1 2 C1 6 ), which represents each aluminium atom as a body 
having four arms or bonds, three of which are engaged in grasping 
the arms of univalent chlorine atoms, while the fourth grasps the 
corresponding arm of its brother aluminium 
Chloride of Aluminium, atom. Such structural formulce — or graph ic 
CI CI formulce, as they are called — are useful in 

| | facilitating the acquirement of hypotheses 

| | regarding the constitution of chemical sub- 

Cl Al Al CI stances, especially if the error be avoided 

| | of supposing that they are pictures either 

I | of the position or absolute power of atoms 

CI CI in a molecule, or, indeed, the true repre- 

sentation of a molecule at all ; for on this 
point man knows little or nothing. A1C1 3 may be the formula at 
very high temperatures. 

Source. — Aluminium is abundant in nature, chiefly as silicate in 
clays, slate, marl, granite, basalt, and a large number of minerals. 
Mica or talc consists chiefly of aluminium, iron, magnesium, and 
potassium silicates. The sapphire and ruby are almost pure alu- 
minium oxide. Rottenstone is a soft, friable aluminium silicate con- 
taining a little organic matter. 

The metal aluminium is obtained from the double aluminium and 
sodium chloride by the action of metallic sodium, the source of the 
chloride being the mineral bauxite, a more or less ferruginous 
aluminium hydrate ; also by electrolysis. It is readily attacked by 
inorganic and organic acids. 

Aluminium readily alloys with other metals. 1 part fused with 9 
of copper gives aluminium bronze. Aluminium steel is a hard and 
tenacious alloy of a little aluminium with the iron. 

Alum (Alumen, U. S. P.), a double aluminium and ammonium 
sulphate (Al 2 3S0 4 ,Am 2 S0 4 ,24H 2 0) or aluminium and potassium 
(A1 2 3S0 4 ,K 2 S0 4 ,24H 2 0), may be obtained from aluminous schist 
(from (x^o-rof, schistos, divided), a sort of pyritous slate or shale, by 
exposure to air; oxidation and chemical change produce aluminium 
sulphate, iron sulphate, and silica from the aluminium silicate and 
iron bisulphide (iron pyrites) originally present in the shale. The 
aluminium sulphate and iron sulphate are dissolved out of the mass 
by water, and ammonium or potassium sulphate or chloride added ; 
on concentrating the liquid, alum crystallizes out, while the more 
soluble iron salt remains in the mother-liquor. 

It is more frequently prepared by directly decomposing the 
aluminium silicate in the calcined shale of the coal-measures by hot 
sulphuric acid, ammonium or potassium salts being added from time 
to time until a solution strong enough to crystallize is obtained. 



ALUMINIUM. 139 

The liquid, well agitated during cooling, deposits alum in minute 
crystals termed alum-flour, which is afterward recrystallized. 

Alums. — There are several alums, iron or chromium taking the 
place of aluminium, and potassium or sodium that of ammonium, 
all crystallizing in an eight-sided form, the octahedron — a sort of 
double pyramid. They are apparently alike in chemical constitu- 
tion, and their general formula (M = either metal) is M /// 2 3S0 4 , 
M / 2 S0 4 ,24H 2 0. The alum of the manufacturer commonly occurs 
in colorless, transparent, octahedral crystals, massed in lumps, 
which are roughly broken up for trade purposes, but still exhibit 
the faces of octahedra. It contains ammonium sulphate or potas- 
sium sulphate, according as one or other is the cheaper. At the 
present time potassium alum is the variety met with in trade, and 
this is the official recognized variety. 

Note on Constitution or Structure. — In presence of the fact that a 
great change in the properties of aluminium sulphate, potassium 
sulphate, and water ensues when those three substances unite to 
form alum, it would seem to be wrong to picture alum by a formula 
still reflecting those three substances ; thus, A1 2 3S0 4 ,K 2 S0 2 ,24H 2 0. 
Many chemists admit this, and find reasonable excuse in sheer 
inability to offer any more probable formula in the present stage 
of chemical knowledge. Many chemists, on the other hand, defend 
the formula, and explain that while no doubt the particles in each 
of the original separate substances are united by atomic or ordinary 
chemical attraction or affinity, those substances are, in alum, united 
by molecular chemical attraction. But this view involves the 
assumption of the existence of either a new force or of two forms 
of chemical force, in which case the old position that permanent 
and entire alterations in properties are due to the action of a single 
force, the chemical force, is no longer tenable. It is to be feared 
that both learner and teacher must be content to remain for the 
present in somewhat of a dilemma. The discovery that resolves 
this dilemma will probably lay bare the cause of the properties and 
phenomena attendant upon the formation of all salts containing 
what is termed "water of crystallization," as well as of "double 
salts," " solutions," " alloys," " amalgams," and perhaps what is 
conveniently spoken of as "the variations in the valency of atoms." 

Preparation of Alum. — Prepare alum by heating a small quantity 
of powdered pipeclay (aluminium silicate) with about twice its 
weight of sulphuric acid for some time, dissolving out the result- 
ing aluminium sulphate and excess of sulphuric acid by water, and 
adding potassium carbonate to the clear filtered solution until, after 
well stirring, the excess of acid is neutralized. (If too much car- 
bonate be added, aluminium hydrate precipitated when the carbon- 
ate is first poured in will not be redissolved on well mixing the 
whole. Perhaps the readiest indication of neutrality in this and 
similar cases is the presence of a little precipitate after stirring and 
warming the mixture.) On evaporating the clear solution, crystals 
of alum are obtained. 

Aluminium Sulphate, or " Alum-cake " (A1 2 3S0 4 ,9H 2 0), prepared 
from natural silicates in the manner just described, is a common 



140 THE METALLIC RADICALS. 

article of trade, serving most of the manufacturing purposes for 
which alum was formerly employed. It is a pure variety, official 
in the United States Pharmacopoeia (Alumini Sulphas). It may be 
made by dissolving aluminium hydrate in diluted sulphuric acid, 
with subsequent removal of water by evaporation. 
Al 2 6HO + 3H 2 S0 4 = A1 2 3S0 4 + 6H 2 0. 
Aluminium hydrate (Alumini Hydras, U. S. P.) is to be prepared 
by the addition of solution of alum to solution of sodium carbonate, 
the precipitated hydrate being collected on a filter and well washed. 

A1 2 3S0 4 ,K 2 S0 4 + 3Na 2 C0 3 + 3H 2 = AL6HO + K„S0 4 + 
3Na 2 S0 4 + 3C0 2 . 

Dried Alum (Alumen JExsiccatum, U. S. P.) is alum from which 
the water of crystallization has been expelled by heat, the temper- 
ature not exceeding 205° C. or 400° F. By calculation from the 
molecular weight of alum, it will be found that the salt contains 
between 47 and 48 per cent, of water. At temperatures above 400° 
F. ammonium alum is decomposed, ammonium sulphate and sul- 
phuric anhydride escaping, and pure aluminium oxide (A1 2 3 ) 
remaining. Dried alum rapidly reabsorbs water from the atmo- 
sphere, and is slowly but completely soluble in water. 

Roche Alum, or Rock Alum (roche, French, rock), is the name of 
an impure native variety of alum containing iron. The article sold 
under this name is generally an artificial mixture of common alum 
with ferric oxide. 

The Ammonio-ferric Alum or Ammonio-ferric Sulplwdc or Ferric 
Ammonium Sulphate of American pharmacy (Ferri et Ammonii 
Sulphas, U. S. P.) may be made by adding ammonium sulphate to 
a hot solution of iron persulphate, and setting the liquid aside to 
crystallize. It forms pale violet octahedral crystals, expressed by 
the formula Fe 2 3S0 4 ,(NH 4 ) 2 S0 4 ,24H 2 0. 

Reactions having Analytical Interest (Tests). 
First Analytical Reaction. — To a solution of an aluminium 
salt (alum, for example, which contains aluminium sulphate) 
add ammonium sulphydrate (NH 4 HS) ; a gelatinous white 
precipitate (aluminium hydrate) falls. 

A1 2 3S0 4 + 6NH 4 HS -f 6H 2 = Al 2 6HO + 3(NH 4 ) 2 S0 4 + 

6H 2 S. 

Second Analytical Reaction. — To solution of alum add ammo- 
nia, NH 4 HO ; aluminium hydrate falls : add excess of ammo- 
nia ; the precipitate is, practically, insoluble. 

Principle of Dyeing by Help of Mordants. — The precipitated 
aluminium hydrate, alumina, has great affinity for vegetable 
coloring-matters and also for the fibre of cloth. Once more 
perform the above experiment, but before adding the ammonia 
introduce some decoction of logwood, solution of cochineal, or 



ALUMINIUM. 141 

other similar colored liquid into the test-tube. Add now the 
ammonia, and set the tube aside for the alumina to fall ; the 
latter takes down with it all the coloring principle. In dye- 
works the fabrics are passed through liquids holding the alumina 
but weakly in solution, and then through the coloring solutions : 
from the first bath the fibres abstract alumina, and from the 
second the alumina abstracts coloring-matter. Some other 
metallic hydrates, notably those of tin and iron, resemble 
alumina in this propert}^ ; they are termed mordants (from 
mordens, biting) ; the substances they form with coloring-mat- 
ters have the name of lakes. 

Third Analytical Reaction. — To the solution of alum add 
solution of potash ; again aluminium hydrate falls. Add excess 
of potash and agitate ; the precipitate dissolves. 

Aluminium hydrate may be precipitated from this solution 
by neutralizing the potash with hydrochloric acid and adding 
ammonia, until, after shaking, the mixture has an ammoniacal 
smell, or by adding solution of ammonium chloride to the 
potash liquid. But the former way is the better, for it is 
difficult to know when a sufficiency of ammonium chloride has 
been poured in ; whereas reaction with blue and red litmus- 
paper at once enables the operator to know when excess of 
hydrochloric acid or of ammonia has been added. 

Alkaline carbonates, phosphates, arseniates, and salts of other 
acidulous radicals also decompose solutions of aluminium salts, 
and produce insoluble compounds of that metal with the several 
acidulous radicals (except the carbonic), but the resulting precipi- 
tates are of no special interest. 



QUESTIONS AND EXEECISES. 

What is there remarkable about the quanti valence of aluminium ? — 
Practically, what is the quantivalence of the atom of aluminium ? — Enu- 
merate the chief natural compounds of aluminium. — Write down a 
formula which will represent either of the alums. — Which alum is 
official, and commonly employed in the arts? — State the source and 
explain the formation of alum. — What is the crystalline form of alum ? 
— Work a sum showing how much dried alum is theoretically producible 
from 100 pounds of alum. Ans. 52 lb. 6 oz. — Show by figures how ordi- 
nary ammonium alum is capable of yielding 11.356 per cent, of alumin- 
ium oxide. — Why are aluminium compounds used in dyeing? — How are 
salts of aluminium analytically distinguished from those of zinc ? 



7* 



142 THE METALLIC RADICALS. 

IRON. 

Symbol, Fe. Atomic weight, 56. 

Sources. — Compounds of iron are abundant in nature. Magnetic 
Iron Ore, or Loadstone {Lodestone or Leadstone, from the Saxon 
Icedan, to lead, in allusion to its use, or rather to the use of magnets 
made from it, in navigation), is the chief ore from which Swedish 
iron is made : it is a compound of ferrous and ferric oxide (FeO,Fe 2 3 ). 
Much of the Russian iron is made from Specular Iron Ore (from 
speculum., a mirror, in allusion to the lustrous nature of the crystals 
of this mineral) : this and Red Haematite (from aljua, haima, blood, 
so named from the color of its streak), an ore raised in Lancashire, 
are composed of ferric oxide only (Fe 2 3 ). Brown Haematite, an 
oxyhydrate, is the source of much of the French iron. Spathic 
Iron Ore (from spatha, a slice, in allusion to the lamellar structure 
of the ore) is a ferrous carbonate (FeC0 3 ). An impure ferrous car- 
bonate forms the Clay Ironstone whence most of the English iron is 
derived. The chief Scotch ore is also an impure carbonate, con- 
taining much bituminous matter : it is known as Black Band. Iron 
Pyrites (from irvp, pur, fire, in allusion to the production of sparks 
when sharply struck), (FeS 2 ), is a yellow lustrous mineral of use 
only for its sulphur. As met with in coal it is commonly termed 
coal brasses. Ferrous carbonate (FeC0 3 ), chloride (FeCl 2 ,4H 2 0), 
and sulphate (FeS0 4 ,7H 2 0) sometimes occur in springs, the water 
of which is hence termed chalybeate {chalybs, stee4). 

Process. — Iron is obtained from its ores by processes of roasting, 
and reduction of the resulting impure oxide with coal or charcoal 
in the presence of chalk, the latter uniting with the sand, clay, etc. 
to form a fusible slag. The cast iron thus produced may be con- 
verted into wrought iron by burning out the 4 or 5 per cent, of car- 
bon, silicon, and other impurities present by oxidation in a furnace 
— the old operation termed puddling. Steel is iron containing from 
1 to 2 per cent, of carbon, and is made by the now celebrated Bes- 
semer process of burning out from cast iron the variable amount of 
carbon it contains, and then adding melted iron containing a known 
proportion of carbon. The official varieties of the metal are " metal- 
lic iron, in the form of fine, bright, and non-elastic wire" (Ferrum, 
U. S. P.) 5 and " annealed iron wire," having a diameter about 0.005 
of an inch (about No. 35 wire gauge), or wrought-iron nails free 
from oxide {Ferrum, B. P.), these being the forms in which iron is 
conveniently employed for conversion into its compounds. In the 
form of a fine powder (see the Seventeenth Reaction) metallic iron is 
employed as a medicine. 

Properties. — The specific gravity of pure iron is 7.844 ; of the 
best bar iron, 7.7. Its color is bluish-white or gray. Bar iron 
requires the highest heat of a wind-furnace for fusion, but below 
that temperature assumes a pasty consistence, and in that state two 
pieces may be joined or welded (Germ, wellen, to join) by the pres- 
sure of blows from a hammer. A little sand thrown upon the hot 
metal facilitates this operation by forming with the superficial iron 
oxide a fusible slag which is dispersed by the blows : the purely 



IRON. 143 

metallic surfaces are thus better enabled to come into thorough con- 
tact and enter into perfect union. Iron is highly ductile, and of all 
common metals possesses the greatest amount of tenacity. At a 
high temperature it burns in the air, forming red iron oxide. Ordi- 
nary iron rust is chiefly ferric oxide, with a little ferrous oxide and 
carbonate ; it is produced by action of the moist carbonic acid of 
the air and subsequent oxidation. Steam passed over scrap iron 
heated to redness gives hydrogen gas and black iron oxide. 

Quantivalence. — Iron combines with other elements and radicals 
in two proportions : those salts in which the atom of iron appears 
to possess inferior affinities (in which the other radicals are in the 
less amount) are termed ferrous, the higher being ferric salts. In 
the former the atom exerts bivalent (Fe // or Fe 2 lv ), in the latter 
trivalent activity (Ye /// or Fe 2 VI ) as seen in the formulae of the chlo- 
rides, FeCl 2 (possibly Fe 2 Cl 4 ) and Fe 2 Cl 6 (perhaps FeCl 3 at very high 
temperatures). 

The atom of iron is also sometimes considered to be sexivalent, 
on account of the analogy of its compounds with those of chromium, 
which is sexivalent if the formula of its fluoride (CrF 6 ) be correct, 
and because the composition of potassium ferrate (K 2 Fe0 4 ), a deep- 
purple salt (obtained on warming a mixture, in a test-tube, of a few 
fragments of solid potassium hydrate and of iron perchloride with 
a few drops of bromine), is best explained on the assumption of the 
sexivalence of its iron. 

Why the quantivalence of such atoms as that of iron should vary 
is not at present known. 

The Nomenclature of Iron Salts. — For educational and descriptive 
purposes, also, the two classes of compounds are very conveniently 
spoken of as ferrous and ferric, the syllable u ferr" common to all, 
indicating their allied ferruginous character, the syllables oils and 
ic indicating the lower and higher class respectively — functions ful- 
filled by these two syllables in other similar cases (sulphurous and 
sulphuric, mercurous and mercuric). In the British Pharmacopoeia 
the iron salts are known by other names ; thus, Sulphate of Iron 
[Ferri Sulphas) and Phosphate of Iron (Ferri Phosphas) — names 
which are chemically inexplicit, for there are two sulphates and two 
phosphates, and the terms do not define which salt is intended. 
Consistency and uniformity would demand that the names ferrous 
sulphate, ferrous phosphate, or similar terms should be employed, 
as is done in the new United States Pharmacopoeia. Practically, 
however, the old names cause no confusion, inasmuch as only one 
sulphate, phosphate, etc. is used in medicine ; moreover, the higher 
salts usually have the prefix per attached (as persulphate, perchlo- 
ride). These names are already well known, can easily be rendered 
in Latin, and then admit of simple abbreviations and adaptations 
such as are employed in prescriptions — advantages not possessed by 
the more rational terms. While, therefore, the comprehension of 
the chemistry of iron is rendered simple and intelligible by the use 
of the terms ferrous and ferric, the employment of older and less 
definite names may be continued in pharmacy as being more conve- 
nient under certain circumstances. 



144 THE METALLIC RADICALS. 

Reactions having Synthetical Interest. 

FERROUS SALTS. 

Ferrous Sulphate. 

Synonyms. — Green Sulphate of Iron ; Green Vitriol. 

First Synthetical Reaction. — Place iron (small tacks) in sul- 
phuric acid diluted with eight times its bulk of water (in a 
test-tube, basin, or other vessel of any required size), accele- 
rating the action by heat until effervescence ceases. 

Fe 2 + 2H 2 S0 4 + *H 2 = 2FeS0 4 + 2H 2 + xH 2 

Iron. Sulphuric acid. Water. Ferrous sulphate. Hydrogen. Water. 

The solution contains what is generally known as sulphate 
of iron — that is, ferrous sulphate — the lower of the two sul- 
phates, and will yield crystals of that substance (FeS0 4 ,7H 2 0), 
\Ferri Sulphas, IT. S. P.), on cooling or on further evaporation ; 
or if the hot concentrated solution be poured into alcohol, the 
mixture being well stirred, the sulphate is at once thrown down 
in minute crystals {Ferri Sulphas Granidatus, U. S. P.), the 
precipitated sulphate of iron of U. S. P. 1880. At a tempera- 
ture of 300° F. ferrous sulphate loses six-sevenths of its water, 
and becomes the dried Ferrous Sulphate {Ferri Sidphas Exsic- 
catus, U. S. P.), a salt used in the preparation of Pilulse Aloes 
et Ferri, U. S. P. (For the nature of the chemical action 
with iron and diluted sulphuric acid see the analogous zinc 
reaction on p. 132.) 

Other Sources of Ferrous Sulphate. — In the laboratory ferrous 
sulphate is often obtained as a by-product in making sulphuretted 
hydrogen. 

FeS + H 2 S0 4 = H 2 S + FeS0 4 . 

In manufactories it occurs as a by-product in the decomposition of 
aluminous shale, as already noticed (p. 138). 

10 grains of granulated ferrous sulphate dissolved in 1 ounce of 
water constitutes " Solution of Sulphate of Iron," B. P. " The 
solution should be recently prepared," because of its liability to. 
absorb oxygen and become spoilt through formation of ferric oxy- 
sulphate (see below). 

Notes. — Ferrous sulphate is sometimes termed green vitriol. Vit- 
riol (from vitrum, glass) was originally the name of any transparent 
crystalline substance : it was afterward restricted to the sulphates 
of zinc, iron, and copper, which were, and still are, occasionally 
known as white, green, and blue vitriol. Copperas (probably orig- 
inally copper-rust, a term applied to verdigris and other green 
incrustations of copper) is another name for this ferrous iron sul- 
phate, sometimes distinguished as green copperas, copper sulphate 
being blue copperas. Ferrous sulphate forms a light-green double 
salt with ammonium sulphate (see p. 91). 



IRON. 145 

Ferrous sulphate, when exposed to the air, gradually turns brown 
through absorption of oxygen, ferric oxysulphate (Fe 2 02S0 4 ) being 
formed. The latter is not completely dissolved by water, owing to 
the formation of a still lower insoluble oxysalt (Fe 4 5 S0 4 ) and the 
soluble ferric sulphate : 5(Fe 2 02S0 4 ) = Fe 4 5 S0 4 + 3(Fe 2 3S0 4 ). 

Iron heated with undiluted sulphuric acid gives sulphurous acid 
gas and ferrous sulphate : 

Fe 2 + 4H 2 S0 4 ='2S0 2 + 2FeS0 4 + 4H 2 0. 

Ferrous Carbonate, or Carbonate of Iron. 

Second Synthetical Reaction. — To solution of ferrous sul- 
phate, boiling, in a test-tube, add a solution of ammonium car- 
bonate (NH 4 ) 2 C0 3 , in recently boiled hot water ; a white pre- 
cipitate of ferrous carbonate (FeC0 3 ) is thrown down, rapidly 
becoming light-green, bluish-green, and, after a long time, red, 
through absorption of oxygen, evolution of carbonic acid gas, 
and formation of ferric oxyhydrate. 

FeS0 4 + (NH 4 ) 2 C0 3 = FeC0 3 + (NH 4 ) 2 S0 4 

Ferrous Ammonium Ferrous Ammonium 

sulphate. carbonate. carbonate. sulphate. 

Sdccharated Ferrous Carbonate. — The above precipitate, rapidly 
washed with hot, well-boiled distilled water, and the moist powder 
mixed with sugar and quickly dried — in short, all possible precau- 
tions taken to avoid exposure to air — forms the saccharated ferrous 
carbonate (Ferri Carbonas Saccharatus, U. S. P.). 

The official proportions are 10 of the sulphate dissolved in 40 of 
hot water, and 7 of the bicarbonate dissolved in 100 of warm water, 
and each filtered. The former is then added to the latter in a flask, 
the mixture shaken, the precipitate washed by decantation until the 
washings give only a very slight turbidity with barium chloride, 
drained, and while still somewhat moist mixed with 16 parts of 
sugar, and finally dried over a water-bath. 

Carbonate of iron, mixed with honey and sugar, forms the Massa 
Ferri Carbonatis, U. S. P., mass of carbonate of iron or mass of 
ferrous carbonate. Saccharated ferrous carbonate, mixed with a 
fourth of its weight of confection of roses, forms the Pilula Ferri 
Carbonatis, B. P. 

Notes. — The red powder formerly termed carbonate or subcarbon- 
ate of iron {Ferri Carbonas or Ferri Subcarbonas) was ferrous car- 
bonate washed and dried with free exposure to air, the product thus, 
by the absorption of oxygen and the elements of water and elimi- 
nation of carbonic acid gas, becoming ferric oxyhydrate, a com- 
pound which will come under notice subsequently (pp. 151-153). 
Ferrous carbonate is said to be more easily dissolved in the stomach 
than any other iron preparation. It is so unstable and prone to 
oxidation that it must be washed in water containing no dissolved 
air and mixed with the sugar (which protects it from oxidation) as 
quickly as possible. In making the official compound mixture of 



146 



THE METALLIC RADICALS. 



iron (Mistura Ferri Composita, U. S. P.), "Griffith's mixture," the 
prepared ingredients, including the potassium carbonate, should be 
placed in a bottle of the required size, space being left for the crys- 
tals or solution of ferrous sulphate, which should be added last, the 
bottle immediately filled up with rose-water and securely corked ; 
the minimum of oxidation is thus ensured. More than two molec- 
ular weights of the potassium carbonate to one of the ferrous sul- 
phate are ordered in the official mixture ; hence, as the ferrous car- 
bonate decomposes, the carbonic acid produced does not necessarily 
escape, but converts potassium carbonate into bicarbonate. Pilulce 
Ferri Compositce (U. S. P. 1880) are made from myrrh, sodium 
carbonate, ferrous sulphate, and syrup : ferrous carbonate is grad- 
ually formed. Iron Pill, or "Blaud's pill," is also prepared with 
ferrous sulphate and potassium carbonate. 

FeS0 4 + K 2 C0 3 = FeC0 3 + K 2 S0 4 . 

Ferrous Arseniate, or Arseniate of Iron. 

Third Synthetical Reaction, by which the lower arseniate of 
iron, ferrous arseniate (Ferri Arsenias, B. P.) (Fe 3 2As0 4 ), par- 
tially oxidized, is formed. This will be noticed again under 
Arsenium. 



Ferrous Phosphate, or Phosphate of Iron. 

Fourth Synthetical Reaction. — To a hot solution of ferrous 
sulphate in a test-tube add a hot solution of sodium phosphate 
and a little of a solution of sodium bicarbonate ; the lower 
phosphate of iron, or ferrous phosphate (Fe 3 2P0 4 ), is precipi- 
tated (Ferri Phosphas Solubilis, U. S. P.). 

3FeS0 4 + 2Na 2 HP0 4 + 2NaHC0 3 = 

Ferrous sulphate. Sodium phosphate. Sodium bicarbonate. 

Fe 3 2P0 4 + 3Na 2 S0 4 + 2H 2 + 2C0 2 

Ferrous phosphate. Sodium sulphate. Water. Carbonic acid gas. 

According to the British Pharmacopoeia, solutions of 3 ounces of 
sulphate of iron in 30 of hot water, and 2f of phosphate in 30 of 
hot water, together with f of an ounce of bicarbonate of sodium 
dissolved in a little water, are well mixed, filtered, the precipitate 
well washed with hot water, and, to prevent oxidation as much as 
possible, dried at a temperature not exceeding 120° F. These pro- 
portions will be found to fairly accord with the molecular weights of 
the crystalline salts, multiplied as indicated in the above equation. 
3(FeS0 4 ,7H 2 0) = 834 ; 2(Na 2 HP0 4 ,12H 2 0) = 716 ; 2(NaHC0 3 ) = 
168. This reaction occurs in making Syrupus Ferri Phosphatis, 
B.P. 

In the United States Pharmacopoeia the ferric phosphate is directed 
to be made from the citrate instead of from the sulphate. 50 grms. 
of ferric citrate are dissolved in water, and 55 grms. of sodium phos- 
phate added ; the mixture is then evaporated on the water-bath to 



IRON. 147 

the consistency of treacle, and spread on glass plates-, it is thus 
obtained in the form of scales. 

The use of the sodium bicarbonate is to ensure the absence of free 
sulphuric acid in the solution. Sulphuric acid is a powerful solvent 
of ferrous phosphate. It is impossible to prevent the separation of 
sulphuric acid if only the 834 parts of ferrous sulphate and 716 
parts of sodium phosphate be employed. Ferrous phosphate is 
white, but soon oxidizes and becomes slate-blue. The official salt 
should contain at least 47 per cent, of hydrous ferrous phosphate, 
Fe :i (P0 4 ) 2 ,8H 2 0, with ferric phosphate and some oxide. 

Ferrous Sulphide, or Sulphide of Iron. 

Fifth Synthetical Reaction. — In a gas flame or spirit flame 
strongly heat sulphur with about twice its weight of iron 
filings in a test-tube (or in an earthen crucible in a furnace) ; 
ferrous sulphide (FeS) is formed. When cold, add water to 
a small portion, and then a few drops of sulphuric acid ; sul- 
phuretted hydrogen gas (H 2 S), known by its odor, is evolved. 

FeS + H 2 S0 4 = FeS0 4 + H 2 S. 

Sticks of sulphur pressed against a white-hot bar of cast iron 
give a pure form of ferrous sulphide. The liquid sulphide thus 
formed is allowed to drop into a vessel of water (Sulphide of Iron, 
B. P.). Or melted sulphur may be poured into a crucible full of 
red-hot iron nails, when a quantity of fluid ferrous sulphide is at 
once formed, and may be poured out on a slab. 

Ferrous Iodide, or Green Iodide of Iron. 

Sixth Synthetical Reaction. — Place a piece of iodine, about 
the size of a pea, in a test-tube, with a small quantity of water, 
and add a few iron filings, small nails, or iron wire. On gently 
warming, or merely shaking if longer time be allowed, the 
iodine disappears, and, on filtering, a clear light-green solution 
of ferrous iodide (FeL) is obtained. On evaporation the solid 
iodide remains. 

Solid ferrous iodide contains about 18 per cent, of water of crys- 
tallization and a little iron oxide. It is deliquescent, and liable to 
absorb oxygen from the air with formation of insoluble ferric oxy- 
iodide or hydrato-iodide. Ferrous iodide thus spoilt may be purified 
by re-solution in water, addition of a little more iodine and some 
iron, warming, filtering, and evaporating as before. Syrup of fer- 
rous iodide which has become brown may usually be restored by 
immersing the bottle in a water-bath and slowly warming. 

Ferrous Bromide (FeBr 2 ) occasionally used in medicine, could be 
made, as might be expected, in the same way as the iodide. Svrupus 
Ferri Bromidi, U. S. P. 1880, contained 10 per cent, of ferrous 
bromide. 

Ferri Iodidum Saccharatum, U. S. P., or Saccharated Ferrous 



148 



THE METALLIC RADICALS. 



Iodide, is made by mixing 6 parts of iron, 17 of iodine, and 20 of 
water, shaking until reaction ceases, filtering into 40 parts of sugar 
of milk, evaporating to dryness with frequent stirring and mixing 
the product in a hot mortar with 20 additional parts of sugar of milk 
and one of reduced iron. It is a grayish or yellowish-white hygro- 
scopic powder. 

Syrupus Ferri Iodidi, or Syrup of Ferrous Iodide, U. S. P., con- 
tains 10 per cent, of the iodide. 

FERRIC SALTS, ETC. 

Ferric Chloride, or Anhydrous Perchloride of Iron. 

Seventh Synthetical Reaction. — Pass chlorine (generated from 
black manganese oxide and hydrochloric acid in a flask) through 
strong sulphuric acid contained in a small bottle, and thence by 
the ordinary narrow glass tubing quite to the bottom of a test- 
tube containing twenty or thirty small iron tacks (or a Florence 
flask containing 2 or 3 ounces ; see Fig. 31), the lattter kept hot 



Fig. 31. 




Preparation of Anhydrous Ferric Chloride. 

by a gas flame ; the higher chloride of iron, ferric chloride, or 
the perchloride * of iron (Fe 2 Cl 6 ) is formed and condenses in 
the upper part of the tube or flask as a mass of small, dark, 
iridescent crystals. When a tolerably thick crust of the salt 
is formed, break off the part of the glass containing it, being 
careful that the remaining corroded tacks are excluded, and 
place it in ten or twenty times its weight of water ; the result- 

* The prefix per (and hyper) used here and elsewhere is from vTi-ep, 
hyper, over or above, and simply means the " highest " of several ; thus 
perchloride, the highest chloride. 



IRON. 149 

ing solution, poured off from any pieces of glass, is a pure 
neutral solution of ferric chloride, and will be serviceable for 
analytical reactions. 

Precaution. — The above experiment must be conducted in the 
open air or in a cupboard having a draught outward. 

Anhydrous Ferrous Chloride. — In breaking up the vessel scaly 
crystals of this substance (FeCl 3 ), of a light buff color, will be 
observed adhering to the nails. 

Note. — Solution of ferric chloride evolves some hydrochloric acid 
on boiling, while a darker-colored solution of ferric oxychloride 
remains. 

Formula of Ferric Chloride. — Qualitative analysis shows that 
ferric chloride contains iron and chlorine. Quantitative analysis shows 
that to 56 parts of iron there are 106.5 parts of chlorine ; total, 162.5. 
And as 56 parts of iron are indicated by the symbol Fe, and 106.5 
of chlorine by the symbol and figure Cl 3 , the formula for ferric 
chloride will, so far. be FeCl 3 . But equal volumes of gases and 
vapors contain equal numbers of molecules (see p. 531). A volume 
which, if water vapor, weighs 18 grains, will if ammonia weigh 17 
grains, or if carbonic acid gas, 44 grains, and if iron perchloride 
vapor, 325 grains. And as these respective volumes contain equal 
numbers of molecules, one molecule of each will be represented by 
the same figures respectively. That is to say, the equal volumes 
differing in weight as the figures 18, 17, 44 and 325 differ, and the 
volumes containing equal numbers of molecules, the respective 
molecules themselves will differ in weight as the figures 18, 17, 44 
and 325 differ. The formula H 2 represents the 18 parts of water, 
or one molecule ; NH 3 , the 17 of ammonia, or one molecule ; C0 2 , 
the 44 of carbonic acid gas, or one molecule ; and the 325 parts by 
weight of ferric chloride can only be represented by the formula 
Fe 2 Cl 6 , for FeCl 3 would only represent half the number thus ob- 
tained by actual experiment. Hence Fe 2 Cl 6 is the formula for a 
molecule of ferric chloride, and not FeCl 3 — at all events, at the tem- 
peratures of the experiments (320° to 440° C). 

Hydrous Ferrous Chloride, or Green Chloride of Iron. 
Solution of Hydrous Ferric Chloride. 

Eighth Analytical Reaction. — Dissolve iron tacks or wire, in 
a test-tube, in hydrochloric acid ; hydrogen escapes, and the 
solution on cooling, or on evaporation and cooling, deposits 
crystallized ferrous chloride, containing four molecules of water 
of crystallization (FeCl 2; 4H 2 0). A syrup of ferrous chloride 
is official (Syrupus Ferri Subchloridi, B. P.). 

Through a portion of the solution of ferrous chloride pass 
chlorine gas ; the ferrous chloride becomes ferric chloride. 

The excess of chlorine dissolved by the liquid in this experiment 
may be removed by ebullition, but the ferric chloride is liable to be 



150 THE METALLIC KADICALS. 

slightly decomposed. The free chlorine is better carried off by 
passing a current of air through the liquid for some time. 



Hydrous Ferric Chloride (the Official 

Ninth Synthetical Reaction. — To another portion of the solu- 
tion of ferrous chloride, in a test-tube, add a little hydrochloric 
acid ; heat the liquid, and continue to drop in nitric acid until 
the black color it first produces disappears ; the resulting red- 
dish-brown liquid is solution of ferric chloride. 



6FeCl 2 + 2HN0 3 


+ 6HC1 = 


3Fe 2 Cl 6 + 2NO + 4H 2 


Ferrous Nitric 


Hydrochloric 


Ferric Nitric Water. 


chloride. acid. 


acid. 


chloride. oxide. 



The black substance is a compound of nitrous oxide gas (NO) 
with a portion of the ferrous salt ; it is decomposed by heat. 

This is the process for producing the solution of chloride of iron, 
Liquor Ferri Chloridi, U. S. P., or Solution of Ferric Chloride, def- 
inite weights of materials being employed and the solution of ferrous 
chloride being poured slowly into the nitric acid. The sp. gr. of 
the liquor is about 1.387. It contains some free hydrochloric acid. 
Percentage of anhydrous chloride, 37.8. Practically, it is impossi- 
ble so to apportion the acids that a solution shall result containing 
neither excess of acid nor of metal, nor contain ferric nitrate. For 
most medicinal purposes, however, solution of ferric chloride con- 
taining hydrochloric acid is said to be unobjectionable. On the 
large scale some time may be saved by adding the acid solution of 
ferrous chloride to the nitric acid. 

If 25 cc. of the above solution be diluted with alcohol up to 
100 cc, the tincture of chloride of iron will be formed (Tinctura 
Ferri Chloridi, U. S. P.), or Tincture of Ferric Chloride. 

Note. — The spirit in the latter preparation is unnecessary, useless, 
and deleterious, for it acts neither as a special solvent nor as a pre- 
servative — the offices usually performed by alcohol (Tincturce et 
Sued, U. S. P. and B. P.) — but, unless the liquid contain excess of 
acid, decomposes the ferric chloride and causes the formation of an 
insoluble oxychloride of iron. Even if the tincture be acid, it 
slowly loses color, ferrous chloride and chlorinated ethereal bodies 
being formed. 

Solution of ferric chloride, evaporated, yields a mass of yellow 
crystals composed of Fe 2 Cl 6 12H 2 0, or, rarely, red crystals having 
the formula Fe 2 Cl 6 5H 2 0. 

Ferric Sulphate, or Persulphate of Iron. 

Tenth Synthetical Reaction. — Dissolve about f of an ounce 
of ferrous sulphate and a sixth of its weight of sulphuric acid 
in 1^ ounces of water in an evaporating-dish, heating the mix- 
ture and dropping in nitric acid until the black color it first 
produces disappears. The resulting liquid, when made of a 
certain prescribed strength, is the solution of ferric sulphate, 



IRON. 151 

or higher sulphate, " Solution of Tersulphate of Iron " of the 
Pharmacopoeia, a heavy, dark-red liquid, sp. gr. 1.320 (Liquor 
Ferri Tersvlphatis, or Solution of Ferric Tersulphate, U. S. P.). 
Solution of subsulphate of iron, Liquor Ferri Subsulphatis or 
Solution of Ferric Subsulphate, U. S. P. (Monsel's solution), 
is a similar fluid, made with less acids, containing, therefore, 
ferric oxysulphate, Fe 4 05S0 4 (sp. gr. about 1.320 at 15° C). 

6FeS0 4 + 3H 2 S0 4 + 2HN0 3 = 3(Fe 2 3S0 4 ) + 2NO + 4H 2 

Ferrous Sulphuric Nitric Ferric Nitric Water, 

sulphate. acid. acid. sulphate. oxide. 

The black color, as in the previous reaction, is due to a compound 
of ferrous salt with nitric oxide (2FeS0 4 + NO). 

The definite official solution of ferric sulphate (Liquor Ferri Per- 
sulphatis, B. P.) is made by adding 6 fluidrachms of sulphuric acid 
to J pint of water, warming, dissolving 8 ounces of crystals of fer- 
rous sulphate in the liquid, then pouring it into nitric acid (6 fluid- 
drachms or rather more) slightly diluted, until the mixture turns to 
a reddish color and ruddy nitrous vapors cease to be produced. The 
whole should measure 11 fluidounces, being diluted or further evap- 
orated, as the case may be, to this bulk. 

Note. — In reactions in which iron passes from ferrous to ferric 
condition it assumes different properties, the atoms of the metal, as 
we believe, passing from bivalent to trivalent activity. 

Ferric Oxyhydrate, or Hydrated Oxide of Iron. 

Eleventh Synthetical Reaction. — Pour a portion of the solu- 
tion of ferric sulphate into excess of solution of ammonia ; 
moist ferric hydrate, Fe 2 6HO, is precipitated. Wash the pre- 
cipitate by decantation or on a filter, and dry it on a plate over 
boiling water ; ferric oxyhydrate, Fe 2 2 (HO) 2 (Ferri Peroxidnm 
Hydratwn, B. P.), remains. When rubbed to a fine powder it 
is fit for medicinal use. 

Ferric Hydrate. 

Synonyms. — Ferric Hydroxide ; Hydrated Oxide of Iron ; Ferric 
Oxyhydrate. 

Ferric hydrate, suspended in a certain quantity of water, 
forms the Ferri Oxidum Hydratum, U. S. P. 

Fe 2 3S0 4 + 6NH 4 HO = Fe 2 6HO + 3NH 4 S0 4 

Ferric sulphate. Ammonia. Ferric hydrate. Ammonium sulphate. 

Fe 2 6HO = Fe 2 2 2HO + 2H 2 

Ferric hydrate. Ferric oxyhydrate. Water. 

Either of the other alkalies (potash or soda) will produce a sim- 
ilar reaction, but ammonia is most convenient. 



152 THE METALLIC RADICALS. 

Ferric hydrate is an antidote to arsenic if administered directly 
after the poison has been taken. It converts the soluble arsenic 
(As 2 3 ) into insoluble ferrous arseniate : 

2(Fe 2 6HO) -f As 2 3 = Fe 3 2As0 4 + 5H 2 + Fe2HO. 

Dried ferric hydrate (then become an oxyhydrate, Fe 2 2 2HO) has 
less action on arsenic. Even the moist, recently prepared hydrate 
(Fe 2 6HO) loses much of this power as soon as it has become converted 
into an oxyhydrate (Fe 4 3 6HO) — a change which occurs though the 
hydrate be kept under water (W. Procter, Jr.). According to T. and 
H. Smith, this decomposition occurs gradually, but in an increasing 
ratio ; so that after four months the power of the moist mass is 
reduced to one-half, and after five months to one-fourth. Now the 
mere loss of water is not usually followed by any alteration of the 
essential chemical properties of a compound. It would seem, there- 
fore, that ferric hydrate (two molecules) (Fe 4 12HO) probably suffers, 
on standing, actual decomposition into oxyhydrate (Fe 4 3 6HO) and 
water (3H 2 0), and does not merely lose water already existing in it 
as water. Ferric hydrate is also far more readily soluble in hydro- 
chloric acid, tartaric acid, citric acid, and acid potassium tartrate 
than ferric oxyhydrate. Any formulae exhibiting ferric hydrate 
(Fe 2 6HO) as a combination of ferric oxide and water (Fe 2 3 ,3H 2 0), 
or the oxyhydrate (Fe 2 2 2HO) as a similar combination (Fe 2 3 ,H 2 0), 
are apparently, for these and other reasons, scarcely correct. 

Ferri Oxidum Hydratum cum Magnesia (Hydrated Oxide of Iron 
with Magnesia, or Ferric Hydrate with Magnesia). — As a more trust- 
worthy arsenic antidote a mixture of solution of ferric sulphate and 
magnesia is recommended in the United States Pharmacopoeia. 
Bottles containing (a) 50 cc. of the official solution of ferric sul- 
phate mixed with twice its weight of water, and (6) 10 parts of 
magnesia well mixed and diluted with 700 of water, are to be kept 
on hand ready for immediate use. Their contents are simply mixed, 
shaken together, and administered to the patient. 

Fe 2 3S0 4 + 3MgO + 3H 2 = 3MgS0 4 + Fe 2 6HO 

Ferric Magnesia. Water. Magnesium Ferric 

sulphate. sulphate. hydrate. 

Ferric Oxide, or Peroxide of Iron. 

The above oxyhydrate, Fe 2 2 2HO, sometimes shortly termed Per- 
oxide of Iron (B. P.), further decomposes when heated to low redness, 
ferric oxide or true iron peroxide (Fe 2 3 ) remaining. 

Fe 2 2 2HO == Fe 2 3 + H 2 0. 

The six univalent atoms of the HO (hydroxy 1), the characteristic 
elements of all hydrates, are thus, by two successive steps, split up 
into water and oxygen. But between the hydrate and oxide there 
obviously may be another oxyhydrate in which only 2HO is dis- 
placed by // ; and such a compound is well known ; it is a variety 
of brown iron ore. The other oxyhydrate,. Fe 2 2 2HO, is also native 
(needle iron ore), as well as being the Ferri Peroxidum Hydratum. 
B.P. 



IRON. 153 

"Ferri Peroxidum Humidum" Fe'" 2 6HO 

A variety of brown iron ore Fe /// 2 // 4HO 

"Ferri Peroxidum Hydratum" (needle ore) Fe /// 2 // 2 2HO 
Ferric oxide Fe /// 2 // s 

The moist ferric hydrate, as already stated, when kept for some 
months, even under water, loses the elements of water, and is con- 
verted into an oxyhydrate, having the formula Fe 4 H 6 9 (limonite or 
brown hsematite), which is either a compound of the above oxy hy- 
drates (Fe 2 04HO + Fe 2 2 2HO) or is a definite intermediate oxyhy- 
drate (Fe 4 3 6HO). 

By ebullition with water for seven or eight hours ferric hydrate 
is decomposed into water and an oxyhydrate having the formula 
Fe 4 H 2 7 (Saint-Gilles), which is either a mixture of the official 
oxyhydrate (Fe 2 2 2HO) with ferric oxide (Fe 2 3 ) or a definite inter- 
mediate body (Fe 4 5 2HO). The relation of these bodies to each 
other will be apparent from the following table, in which, for con- 
venience, the formulae of ferric hydrate and oxide are doubled : 

Ferric hydrate (and as stalactite) Fe 4 12HO 

Kilbride mineral (?) Fe 4 O10HO 

Brown iron ore (Huttenrod and Raschau) Fe 4 2 8HO 

Old, or frozen, ferric hydrate (and limonite) . . , . Fe 4 3 6HO 

Ferric oxyhydrate (B. P.) (and gothite) Fe 4 4 4HO 

Boiled ferric hydrate (and turgite) Fe 4 5 2HO 

Ferric oxide (red haematite, etc.) Fe 4 6 

A ferric oxycarbhydrate (Fe 4 OC0 3 8HO) has been obtained. 

The official ferric oxyhydrate (Fe 2 2 2HO) was formerly made by 
mixing solutions of ferrous sulphate and sodium carbonate, and 
exposing the resulting ferrous carbonate to the air until it was 
nearly all converted into ferric oxyhydrate ; hence its old names, 
still sometimes seen on shop-bottles, of Ferri Carbonas and Ferri 
Subcarbonas. Possibly it sometimes contained a little of the oxy- 
carbhydrate just mentioned. 

Ferric Oxide (another process). 

Twelfth Synthetical Reaction. — Roast a crystal or two of 
ferrous sulphate (mixed with a little sulphur to aid the reduc- 
tion) in a small crucible until fumes cease to be evolved ; the 
residue is a variety of ferric oxide (Fs 2 3 ), or iron peroxide, 
known in trade as red oxide of iron, colcothar, crocus, rouge 
(mineral), Venetian red, etc. It has sometimes been used in 
pharmacy in mistake for the official oxyhydrates (vide Eleventh 
Synthetical Reaction); from which it differs not only in com- 
position, but in the important respect of being almost insoluble 
in acids. 

Ferric Acetate, or Acetate of Iron. 

Thirteenth Synthetical Reaction. — Digest recently washed 



154 THE METALLIC RADICALS. 

and drained ferric hydrate in glacial acetic acid ; ferric acetate, 
Fe 2 6C 2 H 3 2 , is produced. 

Fe 2 6HO + 6HC 2 H 3 2 = Fe 6 6C 2 H 3 2 + 6H 2 

Ferric hydrate. Acetic acid. Ferric acetate. Water. 

The solution of acetate of iron {Liquor Ferri Acetatis, U. S. P.) is 
an aqueous Solution of Ferric Acetate, containing 31 per cent, of 
Fe 2 6C 2 H 3 2 . It is made by dissolving the ferric hydrate prepared 
from a known quantity of ferric sulphate in a definite weight of gla- 
cial acetic acid. Sp. gr. 1.160. 50 parts of this solution, 30 of 
alcohol, and 20 of acetic ether form the Tinctura Ferri Acetatis, 
U. S. P. 1880. 

The " Scale " Compounds of Iron. 

Fourteenth Synthetical Reaction. — Repeat the Eleventh Reac- 
tion, introducing a little solution of citric or tartaric acid or 
acid potassium tartrate, before adding to the alkali (soda, 
potash, or ammonia), and notice that now no precipitation of 
ferric hydrate occurs. This experiment serves to illustrate not 
the manufacture of a scale compound, but the chemistry of 
the manufacture. The effect is due to the formation of double 
compounds, termed ammonio-citrate, potassio-citrate, ammonio- 
tartrate, potassio-tartrate, and similar sodium compounds of 
iron, which remain in solution along with the secondary prod- 
uct — sulphate of the alkali metal. Such ferric compounds, 
made with certain prescribed proportions of recently prepared 
ferric hydrate (from which all alkaline sulphate has been 
washed), and the respective acids (tartaric or citric) or acid 
salts (acid potassium tartrate), etc., and the solutions evaporated 
to a syrupy consistence and spread on smooth plates to dry, 
form the scale preparations known as Ferri et Ammonii Citras, 
U. S. P., Ferri Citras, U. S. P. (also Liquor Ferri Citratis, U. 
S. P.), and Ferri Potassio-tartras, or, rather, Ferrum Tartaratum, 
B. P., Ferri et Potassii Tartras, U. S. P. 

1 part of strychnine and 1 of citric acid with a solution con- 
tainining 98 parts of ferric and ammonium citrate, the mixture 
being evaporated at a temperature not exceeding 60° C. or 140° 
F. to a syrupy consistence, and then scaling in the usual way, 
yield Ferri et Strychninse Citras, U. S. P. 

Specimens of these substances may be prepared by attend- 
ing to the following details : It is essential, first, that the 
ferric hydrate be thoroughly washed, or an insoluble oxysul- 
phate will be formed ; secondly, that the ferric hydrate be 
rapidly washed, or an insoluble ferric oxyhydrate will be pro- 
duced ; thirdly, that the whole operation be conducted quickly, 
or reduction to green ferrous salt will occur ; fourthly, that the 



IRON. 155 

solutions of the salts be not evaporated at a higher tempera- 
ture than that stated, or decomposition will take place ; and, 
fifthly, that excess of ferric hydrate be employed. 

In the pharmacopoeial process for the scale compounds the ferric 
hydrate is in each case freshly made from solution of ferric sul- 
phate by precipitation with solution of ammonia : 



Fe 2 3S0 4 . + 


6NH 4 HO = 


= Fe 2 6HO 


+ 


3(NH 4 ) 2 S0 4 ; 


Ferric 


Ammonium 


Ferric 




Ammonium 


sulphate. 


hydrate. 


hydrate. 




sulphate. 



the solution of ferric sulphate being made of a definite strength 
from a known weight of ferrous sulphate. The reason for adopting 
this course is that ferric hydrate is unstable and cannot be 
weighed, because it cannot be dried without decomposing and 
becoming insoluble, as explained under the Eleventh Reaction. This 
definite solution of ferric sulphate (Liquor Ferri Persulphatis, B. P.) 
is made as already described (see p. 151). 

Ferric Citrate, or Citrate of Iron {Ferri Citras, U. S. P.), and Iron 
and Ammonium Citrate, or Citrate of Iron and Ammonium (Ferri et 
Ammonii Citras, U. S. P.). — Ferric hydrate is dissolved in solution 
of citric acid, and the whole evaporated to dryness with or without 
ammonia. 

To prepare the ferric hydrate, dilute 105 parts of official solution 
of ferric sulphate with water ; pour this into water containing excess 
of " solution of ammonia." (If the opposite course were adopted — 
the alkaline liquid poured into the ferric solution — the precipitate 
would contain ferric oxysulphate or hydrato-sulphate, which inter- 
feres with the brilliancy of the scales.) Thoroughly stir the mix- 
ture (it will smell strongly of ammonia if enough of the latter has 
been used), allow the precipitate to subside, pour away the superna- 
tant liquid, add more water, and repeat the washing until a little of 
the liquid tested for by-product (ammonium sulphate) by solution 
of barium chloride or nitrate ceases to give a white precipitate 
(barium sulphate). Collect the ferric hydrate on a filter, drain, 
and place it, while still moist, with 30 parts of citric acid in an 
evaporating-basin over a water -bath ; stir frequently until the hydrate 
has dissolved. Filter, and either evaporate until the liquid weighs 
100 parts to form the solution of citrate of iron (Liquor Ferri 
Citratis, or Solution of Ferric Citrate, U. S. P.), (sp. gr. about 1.250 ; 
strength 35.5 per cent, of Fe 2 2C 6 H 5 7 ), or evaporate to a syrup at 60° 
C. and spread on glass plates to dry (Ferri Citras, U. S. P., 
Fe 2 2C 6 H 5 7 ,6H 2 0), or to 3 parts of the liquor add 1 of ammonia- 
water and evaporate to form scales (Ferri et Ammonii Citras, 
U. S. P.). 

Ferri et Quinince Citras Solubilis, U. S. P., and Ferri et Quinince 
Citras, B. P., are prepared similarly. Ferric hydrate and pure 
quinine are dissolved in solution of citric acid, ammonia added, and 
the whole evaporated to dryness. The product contains iron 
citrate, quinine citrate, and ammonium citrate. 

The ferric hydrate is obtained from 4J fluidounces of the solution 



156 THE METALLIC RADICALS. 

of ferric sulphate, with all the precautions described in the previous 
paragraph, a proportionate quantity of ammonia being employed. 

While the ferric hydrate is being washed, prepare the quinine by 
dissolving I ounce of the ordinary quinine sulphate in 8 ounces of 
distilled water, acidified with sufficient sulphuric acid to dissolve 
the sulphate (about 12 fluidrachms of the official "diluted sul- 
phuric acid "), and to the clear liquid add solution of ammonia, well 
mixing tin; product by stirring, until the whole of the quinine is 
precipitated (that is, until the mixture, after thorough agitation, 
smells of ammonia). Collect the precipitate on a filter, let it drain, 
and wash away adhering solution of ammonium sulphate by passing 
through it about L] pints of distilled water. 

(It will be observed that the principle involved in the preparation of 
quinine from its sulphate is identical with that which obtains in the 
precipitation of alumina, ferric hydrate, or zinc, hydrate, etc. Such a 
soluble sulphate — or, indeed, any similar soluble salt — has its acidulous 
constituent removed by the superior affinity of the basylous radical in 
ammonia or other alkali, an insoluble precipitate and a new soluble 
sulphate being formed. The latter is washed away, leaving the former 
pure. In such manipulations, when economy has to be practised, soda 
is the alkali generally employed. Ammonia, however, has the advantage 
of showing the moment when its work of removing an acidulous radical 
is completed, for the salts which ammonium forms with such acidulous 
radicals as those represented by the formulae SO*, CI, NO.), and C2H3O2 are 
inodorous, while ammonia lias a powerful odor: so long, therefore, as the 
salt to be decomposed is not wholly attacked, the addition of ammonia 
does not give an ammoniacal odor to the mixture, the ammonia, as such, 
being, in fact, destroyed; but when the work is accomplished the quan- 
tity of ammonia last added remains as ammonia, and communicates its 
natural smell to the liquid.) 

Tin; ferric hydrate and quinine being now washed and drained, 
dissolve the former, and afterward the latter, in a solution of 3 
ounces of citric acid in 5 of distilled water, the acid liquid being 
warmed over a water-bath, and portions of the precipitates stirred 
in as fast as solution is effected. "Let the solution cool, then add, 
in small quantities at a time, 12 fluidrachms of solution of ammonia 
diluted with 2 fiuidounces of distilled water, stirring the solution 
briskly, and allowing the quinine which separates with each addition 
of ammonia to dissolve (in the acid) before the next addition is 
made (excess of ammonia must be avoided, or the quinine will be 
precipitated). Filter the solution, evaporate to the consistence of a 
thin syrup, and then dry in thin layers on flat porcelain or glass 
plates, at a temperature of 100° F. — B. V. 

When dry tin; scales are deliquescent and of a golden-yellow 
color, with a bitter taste, soluble in water, but only partially so in 
alcohol. 

The Ferri et Quinince Citras, U. S. P., is prepared in the same 
way as the soluble salt, with the exception that the ammonia is 
omitted. They are scales of a reddish-brown color. 

Iron and Potassium Tartrate, or Potassio-ferric tartrate (Ferri et 
Potassii Tartras, U. 8. P. ; Ferrum Tartaratum, B. P.). — Ferric 
hydrate is dissolved in solution of acid potassium tartrate, and the 
whole evaporated to dryness. 



IRON. 157 

The ferric hydrate obtainable from 6 fluidounces of the official 
solution of ferric sulphate by the action of ammonia, in the manner 
detailed in the previous paragraphs, is mixed (in a mortar), while 
still moist, but well drained, with 2 ounces of acid potassium tar- 
trate. The whole is set aside for about twenty-four hours, occa- 
sionally triturated to promote contact and reaction of the molecules 
(otherwise somewhat sluggish in attacking each other), and then 
heated in a dish over a water-bath to a temperature not exceeding 
140° F. ; a pint of distilled water is then added, and the mixture 
kept warm until nothing more will dissolve ; filtered, evaporated at 
a temperature not exceeding 140° F. (greater heat causes decompo- 
sition), and, when the mixture has the consistence of syrup, spread 
on panes of glass and allowed to dry (in any warm and open place 
shown by a thermometer to be not much hotter than 100° F.). The 
dry salt is thus obtained in flakes. It should be kept in well-closed 
bottles. 

Ferri et Ammonii Tartras, Iron and Ammonium Tartrate, U. S. P., 
is made by saturating solution of acid ammonium tartrate with ferric 
hydrate, evaporating, and scaling. The acid ammonium tartrate is 
prepared by exactly neutralizing half of any quantity of tartaric 
acid by ammonia-water, and then adding the other half. 

The foregoing are the only official scale preparations of iron. 
Many others of similar character might be formed. The citrate dis- 
solves slowly in cold, but readily in warm, water. Few crystallize 
or give other indications of definite chemical composition. Their 
properties are only constant so long as they are made with unvary- 
ing proportions of constituents. Want of chemical compactness, 
the loose state in which the iron is combined, precludes their recog- 
nition as well-defined chemical compounds, yet possibly enables 
them to be more readily assimilated as medicines than some of the 
more definite ferrous and ferric salts. A definite ferrous tartrate 
(FeC 4 H 4 6 ) and ferrous citrate (FeHC 6 H 5 7 ,H 2 0) have been obtained 
by reaction of iron and acid in hot water. They occur as white, 
gritty masses of microscopic crystals. A sodio-ferrous citrate 
(FeNaC 6 H 5 7 ) and hydrato- citrate (FeNa 2 HOC 6 H 5 7 ) maybe obtained 
in scales. Ferric phosphate (Fe 2 2P0 4 ), when freshly precipitated, is 
soluble in solutions of citrates of the alkali-metals. The official 
Ferri Phosphas Solubilis, U. S. P., is to be made by adding 55 parts 
of sodium phosphate to an aqueous solution of 50 parts of ferric 
citrate, and the mixture evaporated on glass plates to yield scales. 
It is a mixture of ferric phosphate and sodium citrate. 

Wine of Iron, or " steel " wine ( Vinum Ferri, B. P.), made by 
digesting iron wire in sherry wine, probably contains a little potas- 
sium tartrate and iron and other iron salts, formed by action of the 
metal on the small quantities of acid potassium tartrate and tartaric, 
citric, malic and acetic acids present in the wine. Vinum Ferri 
Citratis, B. P., is a solution of iron ammonio-citrate in orange wine. 

Ferric Nitrate, or Pernitrate of Iron. 

Fifteenth Synthetical Reaction. — Place a few iron tacks in 



158 THE METALLIC RADICALS. 

dilute nitric acid and set aside ; solution of ferric nitrate, or 
iron pernitrate, is formed (Fe 2 6N0 3 ). 

Fe 2 + 8HN0 3 = Fe 2 6N0 3 + 4H 2 + 2NO 

Iron. Nitric acid. Ferric nitrate. Water. Nitric oxide. 

Precipitate ferric hydrate from solution of ferric sulphate, 
wash, and dissolve it in nitric acid. 

Fe 2 6HO + 6HN0 3 = Fe 2 6N0 3 + 6H 2 

Ferric hydrate. Nitric acid. Ferric nitrate. Water. 

The latter is the official method for preparing Liquor Ferri Nitratis, 
solution of nitrate of iron or Solution of Ferric Nitrate, U. S. P., 
definite quantities of solution of ferric sulphate and of nitric acid 
being employed. Sp. gr. L050. Strength, about 6.2 per cent, of 
anhydrous nitrate. 

Ferric nitrate and ferric acetate unite to form various aceto- 
nitrates, amongst which is one having the formula Fe 2 (C 2 H 3 2 ) 4 - 
N0 3 HO,4H 2 0, crystallizing in hard, shining, brownish-red 
prisms. 

Reduced Iron. 

Sixteenth Synthetical Reaction. — Pass hydrogen gas (dried by 
passing over pieces of calcium chloride contained in a tube or 
through sulphuric acid in a wash-bottle) over a small quantity 
of ferric oxyhydrate contained in a tube arranged horizontally 
(a test-tube the bottom of which has been accidentally broken 
serves very well), the oxyhydrate being kept hot by a gas flame ; 
oxygen is removed by the hydrogen, steam escapes at the open 
end of the tube, and after a short time, when moisture ceases 
to be evolved, metallic iron, in a minute state of division, re- 
mains. (See Fig. 32.) 

Fe 2 3 + 3H 2 = Fe 2 + 3H 2 

Ferric oxide. Hydrogen. Iron. Water. 

While still hot throw the iron out into the air ; it takes fire 
and falls to the ground as oxide. 

If the ferric oxide is reduced in an iron tube heated by a strong 
furnace, the particles of iron aggregate to some extent, and, when 
cold, are only slowly oxidized in dry air. This latter form of re- 
duced iron is Fer reduit, or, Quevenne's Iron, the Ferri Pulvis or 
Ferrum Reductum, U. S. P. — a fine grayish-black powder, strongly 
attracted by the magnet, and exhibiting metallic streaks when 
rubbed with pressure in a mortar. It is often administered in the 
form of lozenges (Trochisci Ferri Redacti, B. P.), gum and sugar 
protecting the iron from oxidation as well as forming a vehicle for 
its administration. 

Note 1. — The spontaneous ignition of the iron in the above ex- 
periment is an illustration of the influence of minute division on 
chemical affinity. The action is the same as occurs whenever iron 



IRON. 159 

rusts, and the heat evolved and the amount of oxide formed are not 
greater from a given quantity of iron ; but the surface exposed to 
the action of the oxygen of the air is, in the case of this variety of 
reduced iron, so enormous compared with the weight of the iron, 
that heat cannot be conducted away sufficiently fast to prevent 

Fig. 32. 




Preparation of Reduced Iron. 

elevation of temperature to a point at which the whole becomes in- 
candescent. In the slow rusting of iron escape of heat occurs, but is 
not observed because spread over a length of time ; in the sponta- 
neous ignition of reduced iron the whole is evolved at one moment. 
The mixture of lead and carbon (lead pyrophorus) resulting when 
lead tartrate is heated in a test-tube until fumes cease to be evolved, 
spontaneously ignites when thrown into the air, and for the same 
reason. Many substances, solid and liquid, if sufficiently finely 
divided and liable to oxidation, and especially if exposed in a warm 
place, become hot and even occasionally burst into flame spontane- 
ously. Oil on cotton waste, powdered charcoal, coal (especially if 
pyritic, porous, or powdered), resins in powder, and even flour and 
hay, are familiar illustrations of materials liable to " heat," char, or 
even burn spontaneously. 

Note 2. — The student having time and opportunity for the experi- 
ment is advised to convert this sixteenth reaction into a roughly 
quantitative one, by way of realizing what has been stated (see 
again the General Principles of Chemical Philosophy, pp. 35-60) 
respecting the action of chemical force on definite weights only of 
matter. Three tubes, similar to the oxide-tube shown in the en- 
graving, should be prepared, the second being connected to the first, 
and the third to the second, by india-rubber tubing in the usual 
manner. The first tube should contain pieces of calcium chloride to 
absorb any traces of moisture not retained by the sulphuric acid. 
The second tube (the ends of the small tube being temporarily closed 
by small corks) should be weighed in any ordinary scales which will 
turn with a quarter or half a grain, and, the weight being noted, 
160 grains of dry ferric oxide should be neatly placed in the middle 
of the tube. (The oxide before being weighed must be heated gently 



160 THE METALLIC RADICALS. 

in a small crucible over a lamp to remove all traces of moisture.) 
The third tube should contain pieces of calcium chloride to absorb 
the water produced in the reaction, and just before being connected 
should be weighed. The operation is now carried out. At its 
close, and when the middle tube is cold, the latter tube and the 
third tube are again weighed. The oxide-tube should weigh 48 
grains less than before, and the terminal tube 54 grains more than 
before. 



(112 + 48) + 6 =112+54 

The operation is more quickly and easily performed if one-half 
or one-quarter of the weight of oxide be taken ; in that case one- 
half or one-quarter of the weights of iron and of water will be 
obtained. Indeed, any weight of oxide may be employed ; the 
amount of iron and water resulting will be always exactly propor- 
tionate to the weights just mentioned. Thus 16 parts of oxide 
yield 11.2 of iron and 5.4 of water. Iron, hydrogen, and oxygen 
always combine in proportions of 56, of 1, and of 16 respectively. 
Such facts justify us in agreeing that the symbol Fe shall stand for 
56 parts by weight of iron, H for 1 part by weight of hydrogen, 
and for 16 parts by weight of oxygen. 

Ferric Pyrophosphate. 

Seventeenth Synthetical Reaction. — To solution of sodium 
pyrophosphate add solution of ferric sulphate ; a yellowish-' 
white precipitate of ferric pyrophosphate (Fe 4 3P 2 7 ,9H 2 0) 
separates. 

The official Ferri Pyrophosphas Solubilis, or Soluble Ferric 
Pyrophosphate, the Pyrophosphate of Iron, U. S. P. 1880, is 
to.be made by adding 10 parts of sodium pyrophosphate to an 
aqueous solution of 10 parts of ferric citrate, evaporating and 
scaling. The apple-green product is a mixture of ferric pyro- 
phosphate and sodium citrate. 

Dialyzed Iron. 

" Liquor Ferri Dialysatus, B. P. — This solution of dialyzed 
iron, so called, is a solution of about 5 per cent, of highly 
basic ferric oxychloride or chloroxide, from which most of the 
acidulous matter has been removed by dialysis." It is " a 
clear dark, reddish-brown liquid, free from any marked fer- 
ruginous taste." Its specific gravity is about 1.047. {Vide 
" Dialysis " in Index.) 

Reactions having Analytical Interest (Tests). 
(The iron occurring as a ferrous salt.) 
First Analytical Reaction, — Pass sulphuretted hydrogen 



IRON. 161 

(H 2 S) through a solution of a ferrous salt (e. g. ferrous sul- 
phate) slightly acidulated by hydrochloric acid ; no precipitate 
occurs. This is a valuable negative fact, as will be evident 
presently. 

Second Analytical Reaction. — Acid ammonium sulphydrate 
(NH 4 HS) to solution of a ferrous salt ; a black precipitate 
(ferrous sulphide, FeS) falls. 

FeS0 4 + 2NH 4 HS = FeS + (NH 4 ) 2 S0 4 + H 2 S. 

Third Analytical Reaction. — Add solution of potassium fer- 
rocyanide (yellow prussiate of potash), K 4 Fe"Cy 6 , or K i Fcy ///r 
to solution of a ferrous salt ; a precipitate (K 2 Fe"Fe / "Cy 6 , or 
K 2 Fe"Fcy) falls, at first white or bluish gray, but rapidly be- 
coming blue, owing to absorption of oxygen. 

Fourth Analytical Reaction. — To a ferrous salt add potassium 
ferricyanide (red prussiate of potash, K 6 Fe"' 2 Cy 12 , or K 6 Fdcy) ; 
a precipitate falls (Fe" 3 Fe'" 2 Cy 12 , or Fe" 3 Fdcy) (Turnbull's 
blue) resembling prussian blue in color. 

Other Analytical Reactions. — The precipitates produced from 
ferrous solutions on the addition of alkaline carbonates, phos- 
phates, and arseniates, as already described in the synthetical 
reactions of ferrous salts, are characteristic, and hence have a 
certain amount of analytical interest, but are inferior in this 
respect to the four reactions above mentioned. 

Note. — Alkalies (potash, soda, or ammonia) are incomplete 
precipitants of ferrous salts, hence are almost useless as tests. 
To solution of ferrous salt add ammonia (NH 4 HO) ; on filtering 
oiF the whitish ferrous hydrate and testing the solution with 
ammonium sulphydrate, iron will still be found. To another 
portion of the ferrous solution add a few drops of nitric acid 
or excess of chlorine-water, and boil ; this converts the ferrous 
into ferric salt, and now alkalies will wholly remove the iron, 
as already twice seen during the performance of the synthetical 
experiments. 

In actual analysis the separation of iron as ferric hydrate is an 
operation of frequent performance. This is always accomplished 
by the addition of alkali after (if the iron occurs as a ferrous salt) 
previous ebullition with a little nitric acid. Potassium ferrocyanide 
and ferricyanide are the reagents used in distinguishing ferrous 
from ferric salts. 

(The iron occurring as a ferric salt.) 

Fifth Analytical Reaction. — Through a ferric solution (ferric 
chloride, e. g.) pass sulphuretted hydrogen ; a white precipitate 
of the sulphur of the sulphuretted hydrogen falls. The ferric 



162 THE METALLIC RADICALS. 

is simultaneously reduced to a ferrous salt, the latter remaining 
in solution. This reaction is of frequent occurrence in practical 
analysis : 2Fe 2 Cl 6 + 2H 2 S = 4FeCl 2 + 4HC1 + S 2 . 

Sixth Analytical Reaction. — Add ammonium sulphydrate 
to a ferric solution ; the latter is reduced to the ferrous state, 
and a black substance (ferrous sulphide, FeS) is precipitated as 
in the second analytical reaction, sulphur being set free. 

Seventh Analytical Reaction. — To a ferric solution add potas- 
sium ferrocyanide (K 4 FeCy 6 or K^Fcy"") ; a precipitate of 
prussian blue (the common pigment) occurs (Fe^^Fe^Cy,; or 
Fe'" 4 Fcy 3 ""). 

Eighth Analytical Reaction. — To a ferric solution add solution 
of potassium ferricyanide ; no precipitate occurs, but the liquid 
is darkened to a brownish red, or to a greenish or olive hue if 
the salts are not quite pure, 

Ninth Analytical Reaction. — The production of a red precip- 
itate (ferric hydrate) on adding alkalies to ferric salts. It is 
identical with the eleventh synthetical reaction. 

Note. — This reaction illustrates the conventional character of the 
terms synthesis and analysis. It is of equal importance to the 
manufacturer and the analyst, and is synthetical or analytical 
according to the intention with which it is performed. 

Other ferric reactions have occasional analytical interest. In 
neutral ferric solutions the tannic acid in aqueous infusion of 
galls occasions a bluish-black inky precipitate, the basis of 
most black writing-inks. (The Mistura Ferri Aromatica of 
the British Pharmacopoeia, made by digesting metallic iron in 
an infusion of various vegetable substances, contains iron 
tannate, or rather tannates ; it is commonly known in Ireland 
by the name of Heberden's ink, after the physician by whom 
it was first used. It contains about 1 grain of iron in 1 pint.) 
Potassium sulphocyanate (KCyS) causes the formation of ferric 
sulphocyanate, which is of a deep blood-red color. There is 
no normal ferric carbonate ; alkaline carbonates cause the pre- 
cipitation of ferric hydrate, whilst carbonic acid gas escapes. 

Note. — Cyanogen (CN, or Cy'), ferro-cyanogen (FeC 6 N 6 , or FeCy 6 , 
or simply Fcy //// ), and ferri-cyanogen (Fe 2 Cy 12 , or Fdcy VI ) are rad- 
icals which play the part of non-metallic elements, just as ammonium 
in its chemical relations resembles the metallic elements. They will 
be referred to again. 

Memorandum. — The reader must on no account omit to write 
out equations or diagrams expressive of each of the reactions 
of iron, analytical as well as synthetical. It is assumed that 
this has already been done immediately after each reaction has 
been performed. 



IRON. 



163 



DIRECTIONS FOR APPLYING THE FOREGOING ANALYTICAL REAC- 
TIONS TO THE ANALYSIS OF AN AQUEOUS SOLUTION OF 
SALTS CONTAINING OWE OF THE METALS, ZINC, ALUMIN- 
IUM, IRON. 

Add solution of ammonia gradually : 

A dirty-green precipitate indicates iron in the state of a 
ferrous salt. 

A red precipitate indicates iron in the state of a ferric salt. 

A white precipitate, insoluble in excess, indicates the presence 
of an aluminium salt. 

A white precipitate, soluble in excess, indicates zinc. 

These results may be confirmed by the application of some 
of the other tests to fresh portions of the solution. 



TABLE OF SHORT DIRECTIONS FOR APPLYING THE FOREGOING 
ANALYTICAL REACTIONS TO THE ANALYSIS OF AN AQUEOUS 
SOLUTION OF SALTS OF ONE, TWO, OR ALL THREE 
OF THE METALS, ZINC, ALUMINIUM, IRON. 

Boil about half a test-tubeful of the solution with a few 
drops of nitric acid. This ensures the conversion of ferrous 
into ferric salts, and enables the next reagent (ammonia) com- 
pletely to precipitate the iron. Add excess of ammonia, and 
shake the mixture. Filter. 



Precipitate 

AlFe* 

Dissolve in HC1, add excess of KHO, 

stir, filter. 



(red ppt.) 



Filtrate 
Al. 
Make slightly acid by HC1, 
and add excess of NH 4 HOf 
(white ppt.'). 



Filtrate 

Zn. 

Test by NH 4 HS 

(white ppt.). 



* The aluminium precipitate (AI26HO) is white, the iron (Fe26HO), 
red. If the precipitate is red, iron must be and aluminium may be 
present ; if white, iron is absent, and further operations on the ppt. are 
unnecessary. 

This precipitate (AI26HO and Fe26HO) may also, if sufficient is at 
disposal, be analyzed by simply well shaking a washed portion in a tube 
with solution of potash or soda ; the ferric hydrate is not thereby 
affected, while the aluminium hydrate is dissolved, and may be 
detected in the clear decanted fluid by neutralizing all alkali by a 
little excess of acid, and then adding excess of ammonia. 

f Alumina, when in small quantity, is sometimes prevented from 



164 THE METALLIC RADICALS. 

Note 1. — If iron is present, portions of the original solution 
must be tested by potassium ferricyanide for ferrous, and by 
ferrocyanide for ferric salts ; dark-blue precipitates with both 
indicate both ferrous and ferric salts. 

Note 2. — If no ferrous salt is present, ebullition with nitric 
acid is unnecessary. It is perhaps therefore advisable always 
to determine this point previously by testing a little of the 
original solution with ferricyanide ; if no blue precipitate 
occurs, the nitric-acid treatment may be omitted. 

Chart for all Metals hitherto Considered. 

The following table {vide p. 165) is perhaps the best, but not the 
only, adaptation of the ordinary reactions to systematic analysis. 
In it the analytical scheme for the third group is added to that of 
the first two groups. As before, analysis is commenced by the 
addition of ammonium chloride to prevent partial precipitation 
of magnesium, and by ammonium to neutralize any acid, for acid 
destroys the group-precipitant, ammonium sulphydrate, preventing 
its useful action, and causing a precipitation of any free sulphur it 
may contain. Any precipitate by the ammonia may be disregarded, 
for the sulphydrate attacks both solid and liquid. 

Note.— When a test gives no reaction, absence of the body sought 
may fairly be inferred. If a group-test (that is, a test which pre- 
cipitates a group of substances) gives no reaction, the analyst is 
saved the trouble of looking for any of the members of that group. 



QUESTIONS AND EXERCISES. 
Name the chief ores of iron. — How is the metal obtained from the 
ores ? — What is the chemical difference between cast iron, wrought iron, 
and steel? — Explain the process of " welding." — What is the nature of 
Chalybeate waters? — Illustrate by formulae the difference between ferrous 
and ferric salts. — Under what different circumstances may the atom of 
iron be considered to exert bivalent, trivalent, and sexivalent activity? 
Write a paragraph on the nomenclature of iron salts. — Give a diagram 
of the process for the preparation of ferrous sulphate. — In what respects 
do the official ferrous sulphate, granulated ferrous sulphate, and dried 
ferrous sulphate differ ? — How is ferrous sulphate obtained on the large 
scale? — Give the chemical names of white, green, and blue vitriol. — Why 
does ferrous sulphate become brown on exposure to air? — Show the for- 
mation of ferrous carbonate by a diagram. — Describe the action of atmo- 
spheric oxygen on ferrous carbonate ; can the effect be prevented ? — In 
what order would you mix the ingredients of Mistnra Ferri Composita, 
and why? — Write out an equation illustrative of the formation of the 
official phosphate of iron. — Why is sodium bicarbonate used in the 
preparation of ferrous phosphate ? — Name four compounds of iron which 

being precipitated by ammonia through the presence of organic matter 
derived from the filter-paper by action of the potash. In case of doubt, 
therefore, before adding ammonia boil the liquid with a little nitric 
acid, which destroys any organic matter. Avoid great excess of ammonia. 



ANALYTICAL CHART. 



1CJ5 







»? 




_ p 






fD ^j-« 






<> P-> 






^ a> 

% 2- 




v^ Si- 


p <i 

o 2. 






d ^ 'rJ i_j 


Ppt. 

Al 
(white 




21 ™ h-i ^ ^ 


~^ 


n- Qj -rr^ r+ ' 




^ £P [> ^l 

ffi N — PJ 




^> 


2L ^ i_i 


|. g P o 


o » 
Mag 


Fa ° 






h 


H-'^VD 












~ 


^^ 






Q 






2 p ^ 


6;? 




3 


pU /j 






op- p ^ 




t> 




^—sO- 




Filtrate 

Ca 

d (XH 4 ) 2 C 2 

white ppt.), 












^ o 


O 




>! BB 






s !zjeo 


?a* 




S*-CP3 <-t- 


K> 


0> 


a- 






3* 






2-efc? ^ 








0,2 

*. t- > r-t- 

- -no 




o a> p m. 


e» ?° 




f- s-'as? 






p* H_i p p a 


^1 




*"* , 0u (x> 


g» '' 




^ i'r 5 


?d" 




w^a 


^i 










O o 


















v.. 







th 






*■ EC 



. > 

W o 

w a 

H t» 
O 
DC 

o o 

O tH 

si d 

t— ■ i— i 

b o 

w 2 

H 

o 

{> 



8* 



166 THE METALLIC RADICALS. 

may be formed by the direct union of their elements. — Give the official 
method for the preparation of solution of ferric chloride. — Of what use 
is the spirit in tincture of ferric chloride ? — How may ferrous be con- 
verted into ferric sulphate ? — What is the formula of ferric acetate ? and 
how is it prepared for use in pharmacy? — Give the formula for FerriPer- 
oxidum Hydratum, B. P. — How does ferric hydrate act as an antidote to 
arsenic? — What are the properties of anhydrous ferrous oxide? — What 
are the general characters and mode of production of the medicinal scale 
preparations of iron ? — In what state is the iron in Vinum Ferri, B. P. ? — 
What other form of wine of iron is official in B. P. ? — Give a diagram 
showing the formation of ferric nitrate. — Work out a sum showing how 
much ferric oxide will yield, theoretically, one hundredweight of iron. 
Ans. 160 lbs. — Explain the action of the following reagents for iron, dis- 
tinguishing between ferrous and ferric reactions, and illustrating each 
by an equation or a diagram : a. Ammonium sulphydrate. b. Potassium 
ferrocyanide. c. Potassium ferricyanide. d. Caustic alkalies, e. Potas- 
sium sulphocyanate. — Describe the action of ammonia on salts of iron, 
aluminium, and zinc respectively. — What precautions must be used in 
testing for calcium a solution containing iron? — How is magnesium 
detected in the presence of zinc ? — How is aluminium detected in pres- 
ence of magnesium ? — Draw up a scheme for the analysis of an aqueous 
liquid containing salts of iron, barium, and potassium. — How may zinc, 
magnesium, and ammonium be consecutively removed from aqueous 
solution ? 



ARSENUM, AND STIBIUM OR ANTIMONY. 

Nomenclature. — The word arsenic is, throughout the British 
Empire and the United States, understood, and always has been 
understood, to mean common white arsenic, sometimes termed arse- 
nous acid. Any attempt to restrict the word " arsenic " to the 
element itself seems hopeless. Under these circumstances the 
author retains the word arsenum (the analogue of the name of the 
sister element stibium) for the element itself. 

These elements resemble metals in appearance and in the charac- 
ter of some of their compounds, but they are still more closely 
allied to the non-metals phosphorus and nitrogen. Their atoms are 
quinquivalent (As v , Sb v ), as seen in arsenic anhydride (As 2 5 ) and 
antimony pentachloride (SbCl 5 ), but usually exert trivalent activity 
only (As 111 , Sb m ), as seen in the hydrogen and other compounds 
(AsH 3 , AsCl 3 , AsBr 3 , Asl 3 ). The hydrogen compounds of the four 
members of this group have the formulae NH 3 , PH 3 , AsA 3 , SbH 3 . 
A few preparations of these two elements are used in medicine, but 
all are more or less powerful poisons, and hence have considerable 
toxicological interest. 

Arsenum is an exception to the rule that the atomic weights 
(taken in grains, grammes, or other weights) of elements, under 
similar circumstances of temperature and pressure, give equal vol- 
umes of vapor, the equivalent weight (75) of arsenum only occu- 
pying half such a volume. Hence while the molecular weights 
(that is, double the atomic weights) of oxygen (0 2 = 32), hydrogen 
(H 2 = 2), nitrogen (N 2 = 28), etc., give a similar bulk of vapor at 
any given temperature and pressure, the double atomic weight of 
arsenum (As 2 = 150), at the same temperature and pressure, only 



ARSENUM. 167 

affords half this bulk. It would appear, therefore, that the molecule 
of arsenum contains four atoms, and that its formula is As 4 . As in 
the case of sulphur, however, arsenum, in the state ordinarily 
known to us, may be abnormal, and conditions yet be found in which 
the molecular weight is double (instead of quadruple) the atomic 
weight. 

From observed analogy between the two metals the molecular 
constitution of stibium is probably similar to that of arsenum. 



ARSENUM. 

Symbol, As. Atomic weight, 75. 

Sources. — Arsenical ores are frequently met with in Nature, the 
commonest being the iron arsenio-sulphide (FeSAs). This "mis- 
pickel" is roasted in a current of air, the oxygen of which, combin- 
ing with the arsenum, forms common white arsenic, arsenous 
oxide, sometimes called anhydrous arsenous acid, or, better, arse- 
nous anhydride (As 2 3 , or, perhaps, As^OJ or arsenous acid (Acidum 
Arsenosum, U. S. P.), which is condensed in chambers or long flues. 
It commonly " occurs as a heavy white powder or in sublimed 
masses, which usually present a stratified appearance, caused by the 
existence of separate layers differing from each other in degrees of 
opacity." When very much diluted the vapor of arsenic has a 
garlic odor, but it is very poisonous. The vitreous or amorphous 
arsenic is far more soluble than the crystalline variety, and in other 
respects they differ in properties. Such differences between the 
crystalline and amorphous varieties of an element or compound are 
not frequent: they have not yet been satisfactorily explained. 
Realgar (red algar) is the red native arsenum sulphide (As 2 S 2 ), 
and orpiment (auripigmentum, the golden pigment), the yellow 
native sulphide (As 2 S 3 ). The arsenum iodide or tri-iodide (Asl 3 ), 
Arseni lodidum, U. S. P., may be made from its elements or by dis- 
solving white arsenic in aqueous hydriodic acid and evaporating. 
It occurs in small orange-colored crystals, readily and almost entirely 
soluble in water and in rectified spirit. Its aqueous solution has a 
neutral reaction, and gives a yellow precipitate with sulphuretted 
hydrogen. Heated in a test-tube, it almost entirely volatilizes, 
violet vapors of iodine being set free. An aqueous solution of about 
1 per cent, of this arsenous iodide and 1 per cent, of mercuric iodide 
forms the Liquor Arseni et Hydrargyri Iodidi, U. S. P., or Dono- 
van's Solution. 

Reactions having Synthetical Interest. 

Alkaline Solution of Arsenic. 

First Synthetical Reaction. — Boil a grain or two of powdered 
arsenic (As 2 3 ) in water containing a little potassium carbonate, 
and, if necessary, filter. The solution, colored with compound 



168 THE METALLIC RADICALS. 

tincture of lavender, and containing 1 per cent, of arsenic, 
forms the Liquor Potassii Arsenitis, Solution of Potassium 
Arsenite, U. S. P. (Fowler's Solution). 

Note. — This official solution does not generally contain potassium 
arsenite, for the arsenic does not decompose the potassium carbon- 
ate, or only after long boiling. From concentrated solutions car- 
bonic acid gas is more quickly eliminated. 

Arsenous Acid and other Arsenites. 

Arsenic, or arsenous anhydride (the so-called arsenous acid), when 
dissolved in water is said to yield true arsenous acid (H 3 As0 3 ), 
hydrogen arsenite. 

As 2 3 + 3H 2 = 2H,As0 8 

Arsenous anhydride. Water. Arsenous acid. 

When arsenic is dissolved in excess of solutions of potash or soda, 
arsenites are formed having the formulas KH 2 As0 3 and NaH 2 As0 3 . 
Boiled with excess of arsenic, one molecule of these salts combines 
with one of the arsenic. The usual character of such compounds is 
that of oily alkaline liquids. 

Arsenic fused with alkaline carbonates yields pyroarsenates 
(Na 4 As 2 7 or K 4 As 2 7 ) and metallic arsenum. Arsenites have the 
general formula R/ 3 As0 3 . 

Acid Solution of Arsenic. 

Second Synthetical Reaction. — Boil white arsenic with diluted 
hydrochloric acid. Such a solution, made with prescribed pro- 
portions of acid (2 per cent.) and water, and containing 1 per 
cent, of arsenic (As 2 3 ), forms the Solution of Arsenous Acid 
(Liquor Acidi Arsenosi, U. S. P.). De Valangins Solution con- 
tains 1^ grains per ounce. 

Note. — No decomposition occurs in this experiment. The liquid 
is simply a solution of arsenic in the acid. The two solutions may 
be preserved for analytical operations. 

Mem. — The practical student should boil arsenic in water only, 
and thus have an acid, alkaline, and aqueous solution for analytical 
comparison. 

Arsenum. 
Third Synthetical Reaction. — Place a grain or less of white 
arsenic at the bottom of a narrow test-tube, cover it with about 
half an inch or an inch of small fragments of dry charcoal, and 
hold the tube, nearly horizontally, in a flame, the mouth being 
loosely covered by the thumb. At first let the bottom of the 
tube project slightly beyond the flame, so that the charcoal 
may become nearly red-hot ; then heat the bottom of the tube. 
The arsenic will sublime, become deoxidized by the charcoal, 
carbonic oxide being formed, and the element arsenum, some- 
times termed arsenicum, and also, unfortunately, arsenic, be 



ARSENUM. 169 

deposited in the cooler part of the tube as a dark mirror-like 
metallic incrustation. 

There is a characteristic odor, resembling garlic, emitted during 
this operation, probably due to a partially oxidized trace of arsenura 
which escapes from the tube, for white arsenic does not give this 
odor; moreover, .arsenum being a freely oxidizable element, its 
vaporous particles could scarcely exist in the air in an entirely 
unoxidized state. 

Metallic arsenum may be obtained in large quantities by the 
above process if the operation be conducted in vessels of commen- 
surate size. But performed with great care, in narrow tubes, using 
not charcoal alone, but black flux (a mixture of charcoal and potas- 
sium carbonate obtained by heating acid potassium tartrate in a 
test-tube or other closed vessel till no more fumes are evolved), the 
reaction has considerable analytical interest, the garlic odor and the 
formation of the mirror-like ring being highly characteristic of 
arsenum. Compounds of mercury and antimony, however, give 
sublimates which may be mistaken for arsenum. 

Arsenic Acid and other Arsenates. 

Fourth Synthetical Reaction. — Boil a grain or two of arsenic 
with a few drops of nitric acid until red fumes cease to be 
evolved ; evaporate the solution in a small dish to dryness, to 
remove excess of nitric acid ; dissolve the residue in water : the 
product is arsen'ic acid (H 3 As0 4 ). 

Arsenic acid, when strongly heated, loses the elements of water, 
and arsenic anhydride remains (As 2 5 ). 

Arsenic anhydride readily absorbs water and becomes arsenic 
acid (H 3 As0 4 ). Arsenic acid is reduced to arsenous by the action 
of sulphurous acid (H 3 As0 4 + H 2 S0 3 = H 3 As0 3 + H 2 S0 4 ). 

Salts analogous to arsenic acid, the hydrogen arsenate, are 
termed arsenates, and have the general formula B/ 3 As0 4 . The 
ammonium arsenate, (NH 4 ) 2 HAs0 4 , may be made by neutralizing 
arsenic acid with ammonia. Its solution in water forms a useful 
reagent. Arsenic acid is used as an oxidizing agent in the manu- 
facture of the well-known dye, magenta. 

Sodium arsenite and arsenate are used in the cleansing operations 
of the calico-printer. 

Sodium Pyroarsenate and Arsenate. 

Fifth Synthetical Reaction. — Fuse two or three grains of 
common white arsenic (As 2 3 ) with sodium nitrate {NaN0 3 ) 
and dried sodium carbonate (Na 2 C0 3 ) in a porcelain crucible, 
and dissolve the mass in water ; solution of sodium arsenate 
(Na 2 HAs0 4 ) results. 
As 2 3 + 2NaN0 3 + Na 2 C0 3 = Na 4 As 2 7 + N a 8 + C0 2 

Arsenic. Sodium Sodium Sodium Nitrous Carbonic 

nitrate. carbonate. pyroarsenate. anhydride, acid gas. 



170 THE METALLIC RADICALS. 

The official proportions (B. P.) are 10 of arsenic to 8J of sodium 
nitrate and 5J of dried carbonate, each powdered, the whole well 
mixed, fused in a crucible at a red heat till effervescence ceases, and 
the liquid poured out on a slab. The product is sodium pyroar- 
senate (Na 4 As 2 7 ). Dissolved in water, crystallized, and dried, the 
salt has the formula Na 2 HAs0 4 ,7H 2 {Sodii Arsenas, U. S. P.), the 
old arseniate of soda. 

Na 4 As 2 7 + 15H 2 = 2(Na 2 HAs0 4 ,7H 2 0). 

Heated to 300° F., the crystals lose all water. A solution of 1 
per cent, of the anhydrous salt (Na 2 HAs0 4 ) in water forms the 
Liquor Sodii Arsenatis, Solution of Sodium Arsenate, U. S. P. It has 
about half the arsenical strength of Liquor Arsenicalis, B. P. The 
anhydrous salt is used because the crystallized is of somewhat 
uncertain composition. The fresh crystals are represented by the 
formula Na 2 HAs0 4 , 12H 2 (= 53.7 per cent, of water) ; these soon 
effloresce and yield a stable salt having the formula Na 2 HAs0 4 ,7H 2 
(=40.4 per cent, of water). To avoid the possible employment of 
a mixture of these bodies, the invariable anhydrous salt is officially 
used, constancy in the strength of a powerful preparation being 
thereby secured. 

The student will find useful practice in verifying, by calculation, 
the above numbers representing the centesimal proportion of water 
in the two sodium arsenates. This will be easy if what has already 
been stated respecting a symbol representing a number as well as a 
name, and the remarks concerning molecular weight, be remembered. 

The shape of each of the two varieties of sodium arsenate 
(Na 2 HAs0 4 ,12H 2 and Na 2 HAs0 4 ,7H 2 0) is identical with that of 
the corresponding sodium phosphate (Na 2 HP0 4 ,12H 2 and Na 2 - 
HP0 4 ,7H 2 0) 5 the structure of the molecule of the 12-arsenate is 
the same as that of the 12-phosphate, and the 7-arsenate as that of 
the 7-phosphate ; the two former are isomorphous, the two latter are 
isomorphous. This is only one instance of the strong analogy of 
arsenium and its compounds with phosphorus and its corresponding 
compounds. The preparation and characters of the next substance, 
ferrous iron arsenate, will remind the learner of ferrous iron phos- 
phate. 

Ferrous Arsenate, or Arsenate of Iron. 

Sixth Synthetical Reaction. — To a hot solution of sodium 
arsenate add a hot solution of ferrous sulphate and a little 
solution of sodium bicarbonate ; a precipitate of ferrous arse- 
nate occurs (Fe 3 2As0 4 ) (Ferri Arsenias, B. P.). On a larger 
scale, 15f parts of dried arsenate dissolved in 100 of hot 
water, and 20f of sulphate in 120 of hot water, with 4 J of 
bicarbonate, may be employed. The precipitate should be col- 
lected on a calico filter, washed, squeezed, and dried at a low 
temperature (100° F.) over a water-bath, to avoid excessive 
oxidation. 



ARSENUM. 171 

2Na 2 HAsO, + 2NaHC0 3 + 3FeS0 4 = 

Sodium arsenate. Sodium bicarbonate. Ferrous sulphate. 

Fe 3 2As0 4 + 3Na 2 S0 4 + 2H 2 + 2C0 2 . 

Ferrous arsenate. Sodium sulphate. Water. Carbonic acid gas. 

The use of the sodium bicarbonate is to ensure the absence of free 
sulphuric acid in the solution. This acid is a solvent of ferrous 
arsenate. It is impossible to prevent its separation if only the fer- 
rous sulphate (three molecular weights) and sodium arsenate (two 
molecular weights) be employed. 

At the instant of precipitation ferrous arsenate is white, but rap- 
idly becomes of a green or greenish-blue color, owing to absorption 
of oxygen and formation of a ferrosoferric arsenate. When dry, it 
is a tasteless, amorphous, much-oxidized powder, soluble in acids. 



The Arsenum Hydrides and Sulphides and the Copper and Silver 
Arsenites and Arsenates are mentioned in the following analytical 
paragraphs. 

Reactions having Analytical Interest (Tests). 
First Analytical Reaction. — Repeat the third synthetical 
reaction, operating on not very much more white arsenic than 
the bulk of a small pin's head, and using not charcoal alone, 
but the black flux already mentioned (p. 169) or a well-made 
and perfectly dry mixture of charcoal and potassium carbonate, 
the latter best obtained by heating potassium bicarbonate. The 
tube employed should be a narrow test-tube, or, better, a tube 
(easily made from glass tubing) having the form (Berzelius's) 
shown in Fig. 33. 

Fig. 33. 




The white arsenic and black flux are placed in the bulb of 
the tube, which is then heated in a flame ; the arsenum con- 
denses on the constricted portion of the tube. If now the 
bulb be carefully fused off in a flame, the arsenum may be 
chased up and down the narrower part of the tube until the 
air in the tube has reoxidized it to arsenous anhydride. 

If the operation has been performed in a less delicate manner 
in an ordinary test-tube, cut or break off portions of the tube 
containing the sublimate of arsenum, put them into a test- 
tube and heat the botom of the latter, holding it near horizon- 
tally, and partially covering the mouth with the finger or 



172 THE METALLIC RADICALS. 

thumb : the arsenum will absorb oxygen from the air in the 
tube, and the resulting arsenous anhydride (As 2 3 ) be depos- 
ited on the cool part of the tube in brilliant, generally im- 
perfect, octahedral crystals. 

Microscopic Test. — Prove that the crystals are identical in 
form with those of common white arsenic by heating a grain 
or less of the latter in another test-tube, examining the two 
sublimates by a good lens or compound microscope. 

The appearance of a sublimate of white nrsenic is peculiar 
and quite characteristic. The primary form of each crystal is 

Fig. 34. Fig, 34a. 





A Sublimate of White Arsenic (magnified). A Perfect Octahedron. 

an octahedron (dxrib, okto, eight ; edpa, hedra, side) (Fig. 34a), 
or, rarely, a tetrahedron, and in a sublimate a few perfect 
octahedra are generally present. Usually, however, the crystals 
are modifications of octahedra, such as are shown in Fig. 34, 
which is drawn from actual sublimates. 

Second Analytical Reaction. — Place a thin piece of copper, 
about a quarter inch wide and half inch long, in a solution of 
white arsenic, acidified by hydrochloric acid, and boil (nitric 
acid must not be present, or the piece of metal will be dis- 
solved) ; arsenum is deposited on the copper in a metallic con- 
dition. (Memorandum. — An equivalent proportion of copper 
goes into solution. The experiment forms an illustration of a 
class of chemical changes appropriately termed changes by 
substitution.) Pour off the supernatant liquid from the copper, 
wash the latter with water, dry the piece of metal by holding 
it in the clean fingers and passing through a flame, and finally 
place it at the bottom of a clean, dry, narrow test-tube or a 
Berzelius tube, and sublime as described in the last reaction, 
again noticing the form of the resulting crystals. 

This is commonly known as Reinsch's test for arsenum, it having 



ARSENUM. 



173 



been introduced by Reinsch in 1843. The tube may be reserved for 
subsequent comparison with an antimonial sublimate. 

Note. — Copper itself frequently contains arsenum — a fact that 
may not, perhaps, much trouble an operator so long as he is per- 
forming experiments in practical chemistry merely for educational 
purposes, but when he engages in the analysis of bodies of unknown 
composition, he must assure himself that neither his apparatus nor 
materials already contain the element for which he is searching. 

The detection of arsenum in metallic copper is best accomplished 
by distilling a mixture of a few grains of the sample with five or six 
times its weight of ferric hydrate or chloride (free from arsenum) 
and excess of hydrochloric acid. The arsenum is thus volatilized 
in the form of arsenum chloride, and may be condensed in water 
and detected by sulphuretted hydrogen (Sixth Analytical Reaction) 
or Reinsch's test. The ferric chloride solution is, if necessary, freed 
from any trace of arsenum by evaporating once or twice to dryness 
with excess of hydrochloric acid. 

Third Analytical Reaction — The Hydrogen Test or "Marstis" 
Test. — Generate hydrogen in the usual way from water by zinc 
and sulphuric acid, a bottle of about four or six ounces capacity 
being used, and a funnel-tube and short delivery-tube passing 
through the cork in the usual manner- (see following figure). 
Dry the escaping hydrogen (except in rough experiments, 
when it is unnecessary) by adapting to the deli very -tube, by a 
pierced cork, a short piece of wider tubing filled with fragments 
of calcium chloride (a). To the opposite end of the drying- 
tube fit a piece of narrow tubing ten or twelve inches long, 
made of hard German glass, and having its aperture narrowed 
by drawing out in the flame of the blowpipe. When the hydro- 



Fig 35. 




The Hydrogen Test for Arsenum. 



gen has been escaping for a sufiicient number of minutes, and 
at such a rate as to warrant the operator in concluding that all 



174 THE METALLIC RADICALS. 

the air originally existing in the bottle has been expelled, set light 
to the jet, and then pour eight or ten drops of the aqueous 
solution of arsenic, or three or four drops of the acid or alka- 
line solution of white arsenic, previously prepared, into the 
funnel-tube, washing the liquid into the generating-bottle with 
a little water. The white arsenic is at once reduced to the 
state of arsenum, and the latter combines with some of the 
hydrogen to form arsenum hydride or arseniuretted hydrogen 
gas (AsH 3 ). Immediately hold a piece of earthenware or por- 
celain (the lid of a porcelain crucible (b) if at hand) in the 
hydrogen jet at the extremity of the delivery-tube; a brown 
spot of arsenum is deposited on the porcelain. Collect several 
of these spots, and retain them for future comparison with 
antimonial spots similarly obtained (p. 185). 

The separation of arsenum in the flame is due to the decomposition 
of the arseniuretted hydrogen by the heat. The cool porcelain at 
once condenses the arsenum, and thus prevents its oxidation to 
white arsenic, which would otherwise take place at the outer edge 
of the flame. 

Hold a small beaker (c) or wide test-tube over the flame for 
a few minutes ; a white film of arsenic (As 2 3 ) will be slowly 
deposited, and may be further examined in contrast with a 
similar antimonial film (p. 185). 

During these experiments the effect produced by the arsenical 
vapors on the color of the hydrogen flame will have been noticed ; 
they give it a dull, livid, bluish tint. This is characteristic. 

Apply the flame of a gas-lamp to the middle of the hard 
glass delivery -tube (cZ) ; the arseniuretted hydrogen, as before, 
is decomposed by the heat, but the liberated arsenum imme- 
diately condenses in the cool part of the tube, beyond the 
flame, as a dark metallic mirror. The tube may be removed 
and kept for comparison with an antimonial deposit (p. 185). 

Note 1. — Zinc, like copper, frequently itself contains arsenum. 
When a specimen free from arsenum is met with, it should be re- 
served for analytical experiments, or a quantity of guaranteed 
purity should be purchased of the dealers in such articles. Sul- 
phuric acid is more easily obtained free from arsenic. 

Note 2. — In delicate and important applications of Marsh's test 
magnesium may be substituted for zinc with safety, as arsenum has 
not yet been, and is not likely to be, found in magnesium. Magne- 
sium in rods is convenient for this purpose, and may be obtained 
from most dealers in chemical substances. Both magnesium and 
zinc, if perfectly pure, react with acids extremely slowly ; the 
addition of a very little platinum perchloride, however, at once pro- 
motes an abundant evolution of hydrogen. But platinum has a 



ARSENUM. 175 

tendency to hold back arsenum. According to Dyer, rod zinc has 
a similar tendency, while granulated zinc at once gives arseniuretted 
hydrogen. 

Note 3. — Sulphuric acid, which is often used for drying gases, 
decomposes arseniuretted hydrogen. Calcium chloride is the 
appropriate desiccating agent for this gas. 

Note 4- — The original apparatus proposed by Mr. Marsh, a phar- 
macist of Woolwich, England, in 1836, was a U-shaped tube, one 
limb of which was short and closed by a stopcock, so that the whole 
of a small quantity of arseniuretted hydrogen could be collected 
and be examined at leisure. 

Fourth Analytical Reaction — Fleitmanns Test. — Generate 
hydrogen by heating in the test-tube, to near the boiling-point, 
a strong solution of caustic soda or potash and some pieces of 
zinc (Zn + 2NaHO = H 2 + Na 2 Zn0 2 , sodium zincate). Add 
a drop of arsenical solution. Now spread over the mouth of 
the tube a cap of filter-paper moistened with one drop of solu- 
tion of silver nitrate, Again heat the tube, taking care that 
the liquid itself shall not spurt up on to the cap. A plug of 
cotton wool may even be placed in the mouth of the test-tube 
to prevent this spurting. The arsenic is reduced to arsenum, 
the latter uniting with the hydrogen, as in Marsh's test; and 
the arseniuretted hydrogen, passing up through the cap, reacts 
on the silver nitrate, and gives rise to an excellent test by caus- 
ing the production of a purplish-black spot (of silver). 

AsH 3 + 3H 2 + 6AgN0 3 = H 3 As0 3 + 6HN0 3 + 3Ag 2 . 

Note 1. — This reaction is particularly valuable, enabling the ana- 
lyst to quickly distinguish arsenum in the presence of its sister ele- 
ment antimony, which, although it combines with the hydrogen 
evolved from dilute acid and zinc, does not combine with the hydro- 
gen evolved from solution of alkali and zinc, and therefore does not 
give the effect just described. 

Note 2. — Aluminium answers as well as zinc for Fleitmann's test 
(Gatehouse), or magnesium may be used, or, instead of zinc and 
alkali, weak sodium amalgam may be employed (Davy). 

Fifth Analytical Reaction — Bettendorjff s Test. — To a solution 
of stannous chloride in strong hydrochloric acid add a very 
small quantity of any arsenical solution. Arsenum then sep- 
arates, especially on the application of heat, giving the mixture 
a yellowish and then brownish hue or grayish-brown turbidity, 
or even a sediment of ' gray-brown flocks, according to the 
amount present. Much water prevents the reaction ; its pres- 
ence, therefore, must be avoided as far as possible ; indeed, a 
liquid saturated by hydrochloric acid gas gives best results. 
Arsenic in sulphuric or hydrochloric acid or in tartar emetic, 



176 THE METALLIC RADICALS. 

etc. may be detected by this method. Nitrates, such as bis- 
muth subnitrate, must first be heated with sulphuric acid to 
remove the nitric radical before applying this reduction-test for 
arsenum. The stannous is converted into stannic salt during 
the reaction. 

Distinction between Arsenous and Arsen'ic Combinations. — The 
above tests are those for arsenum, whether existing in the arsenous 
or arsenic condition, though the element is not so easily attacked 
when it is in the latter as when it is in the former state. Of the fol- 
lowing reactions, that with silver nitrate at once distinguishes arsen- 
ous acid and other arsenites from arsenic acid and other arsenates. 

Mem. — The exact nature of all these analytical reactions will be 
more fully evident if the student will perseveringly trace them out 
by diagram or equations. 



Sixth Analytical Reaction. — Through an acidified solution of 
arsenic pass sulphuretted hydrogen ; a yellow precipitate (arse- 
num sulphide or arsenous sulphide, As 2 S 3 ) quickly falls. Add 
an alkaline hydrate or sulphydrate to a portion of the precip- 
itate ; it readily dissolves. The precipitate consequently would 
not be obtained on passing sulphuretted hydrogen through an 
alkaline solution of arsenic. To another portion of the pre- 
cipitate, well drained, add strong hydrochloric acid ; it is insol- 
uble, unlike antimony sulphide. (Neither sulphide is soluble 
in the weak acid.) 

Note 1. — Cadmium also affords a yellow sulphide in an acid solu- 
tion by action of sulphuretted hydrogen, but this sulphide is insol- 
uble in alkaline liquids. Under certain circumstances tin, too, yields 
a yellow sulphide, but tin is otherwise easily distinguished. ( Vide 
"Tin" in Index.) 

Note 2. — A trace of arsenum sulphide is sometimes met with in 
sulphur (distilled from arsenical pyrites). It may be detected by 
digesting the sulphur in solution of ammonia, filtering, and evap- 
orating to dryness ; a yellow residue of arsenum sulphide is 
obtained if that substance be present. 

Seventh Analytical Reaction. — Through an acidified solution 
of arsenic acid, or any other arsenate, pass a rapid current of 
sulphuretted hydrogen ; a yellow precipitate (arsenic sulphide, 
As 2 S 5 ) slowly falls. Brauner and Tornicek state that by a slow 
current the arsenic acid is gradually reduced to the arsenous, 
and a yellow precipitate of arsenous sulphide and sulphur 
(As 2 S 3 + S 2 ) slowly falls. The precipitate is soluble in alkaline 
hydrates and sulphydrates. This reaction is more rapid if the 
solution be warmed. 



AESENTJM. 177 

Chemical Analogy of Sulphur and Oxygen. — The potassium 
arsenite and sulph-arsenite, arsenate and sulph-arsenate, have the 
composition represented by the following formulae : 

K 3 As0 3 K 3 As0 4 

K 3 AsS 3 K 3 AsS* ; 

and the corresponding ammonium and sodium salts have a similar 
composition : 

6NH 4 HS + As 2 S 3 = 2(NH i ) 3 AsS 3 + 3H 2 S. 
6NH.HS + As 2 S 5 = 2(NHJ 3 AsS 4 + 3H 2 S. 

Eighth Analytical Reaction. — To an aqueous solution of 
arsenic add two or three drops of solution of copper sulphate, 
and then cautiously add diluted solution of ammonia, drop by 
drop, until a green precipitate is obtained. The production of 
this precipitate is characteristic of arsenum. To a portion of 
the mixture add an acid ; the precipitate dissolves. To another 
portion add alkali ; the precipitate dissolves. These two exper- 
iments show the advantage of testing a suspected arsenical 
solution by litmus-paper before applying this reaction — if acid, 
cautiously adding alkali ; if alkaline, adding acid till neutrality 
is obtained. Or a special copper reagent may be used. (See a 
note to the Eleventh Analytical Reaction.) 

The precipitate is copper arsenite (Cu // HAs0 3 ) or ScheeWs Green. 
More or less pure or mixed with copper acetate or, occasionally, car- 
bonate, it is used as a pigment under many names, such as Bruns- 
wick Green and Schweinfurth Green, by painters and others. 

Ninth Analytical Reaction. — Apply the test just described 
to a solution of arsenic acid or other arsenate ; a somewhat 
similar colored precipitate (copper arsenate) is obtained. 

Tenth Analytical Reaction. — Repeat the eighth reaction, sub- 
stituting silver nitrate for copper sulphate : in this case a yel- 
low precipitate (silver arsenite, Ag 3 As0 3 ) falls, also soluble in 
acids and alkalies. 

Eleventh Analytical Reaction. — Apply the silver test to a 
solution of arsenic acid or other arsenate ; a chocolate-colored 
precipitate (silver arsenate, Ag 3 AsO*) falls. 

This reaction may be utilized for the detection of arsenic when 
occurring in ores and other substances, as ordered by the U. S. Phar- 
macopoeia in the case of Antimonii Sulphidum Purification : 

" If 2 grms. of the sulphide be mixed and cautiously ignited, in a 
porcelain crucible, with 8 grms. of pure sodium nitrate, and, after 
cooling, the fused mass be boiled with 25 cc. of water, there will 
remain a residue which should be white or nearly so, and not yel- 
lowish nor brownish (absence of other metallic sulphides). On boil- 
ing the filtrate separated from the last-mentioned residue with a 



178 THE METALLIC RADICALS. 

slight excess of nitric acid until no more nitrous vapors are evolved, 
then dissolving it in 0.1 grm. of silver nitrate, filtering again if 
necessary, and cautiously pouring a few drops of ammonia-water on 
top, not more than a white cloud, but no red or reddish precipitate, 
should appear at the line of contact of the two liquids (absence of 
more than about 0.1 per cent, of arsenic)." 

Copper and Silver Reagents for Arsenum. — The last four reac- 
tions may be performed with increased delicacy and certainty of 
result if the copper and silver reagents be previously prepared in 
the following manner : To solution of pure copper sulphate (about 
1 part in 20 of water) add ammonia until the blue precipitate at 
first formed is nearly, but not quite, redissolved ; filter and preserve 
the liquid as an arsenum reagent, labelling it Solution of Ammonio- 
Sulphate of Copper (B. P.). Treat solution of silver nitrate (about 
1 part in 40) in the same way, and label it Solution of Ammonio- 
Nitrate of Silver (B. P.). The composition of these two salts will be 
referred to subsequently. 

Arsenous and Arsenic Compounds. — While many reagents 
may be used for the detection of arsenum, only silver nitrate, 
as already stated, will readily indicate in which state the arse- 
num exists ; for the two sulphides and the two copper precip- 
itates, though differing in composition, resemble each other in 
appearance, whereas the two silver precipitates differ in color 
as well as in composition. 

Soluble arsenates give insoluble arsenates with solutions of 
salts of barium, calcium, zinc, and other metals. 

In a group-testing, arsenum, if existing as arsenic acid or other 
arsenate, is not readily affected by such tests as sulphuretted 
hydrogen or even by nascent hydrogen. Hence, if its presence 
in that state is suspected, the liquid under analysis should be 
warmed with a little sulphurous acid (vide p. 169), and then 
tested with sulphuretted hydrogen. 

Antidote. — In cases of poisoning by arsenic or arsenical prep- 
arations the most effective antidote is recently precipitated 
moist ferric hydrate {Ferri Oxidum Hydratum, U. S. P.), 
administered as soon as possible. It is perhaps best admin- 
istered in the form of a mixture of, or solution of, ferric sul- 
phate (Liquor Ferri Ter sulphas, U. S. P.), or ferric chloride 
(Liquor or Tincturd) with sodium carbonate — 2 to 3 ounces of 
the former to about 1 ounce of the crystals of the latter. 
Instead of the sodium carbonate, about \ ounce of calcined 
magnesium may be used. (See Ferri Oxidum Hydratum cum 
Magnesia, U. S. P., page 152.) These quantities will render 
at least 10 grains of arsenic insoluble. Emetics should also be 
given, and the stomach-pump, or a common india-rubber tube 
worked as a siphon (p. 116), be applied as quickly as possible. 



ANTIMONY. 179 

The above statements regarding the antidote for arsenic may be 
verified by mixing the various substances together, filtering, and 
proving the absence of arsenum in the filtrate by applying some of 
the foregoing tests. 

Mode of Action of the Antidote. — The action of the sodium carbon- 
ate or the magnesia is to precipitate ferric hydrate (Fe 2 6HO) — 
sodium chloride (NaCl) or magnesium chloride (MgCl 2 ) being 
formed, which are harmless, if not beneficial, under the circum- 
stances. The reaction between the ferric hydrate and the arsenic 
results in the formation of insoluble ferrous arsenate. (See also p. 
152.) 



2(Fe 2 6HO) -f As 2 3 = 


= Fe 3 2As0 4 + 5H 2 + Fe2HO 


Ferric Arsenic. 


Ferrous Water. Ferrous 


hydrate. 


arsenate. hydrate. 



The so-called solution of dialyzed iron (see Index) is also, as 
might be expected from its composition, an antidote to arsenic. It 
should be administered with a little sodium or potassium bicarbon- 
ate, or with magnesia, or with any other salt which serves to neu- 
tralize any acid that may be present. 



QUESTIONS AND EXERCISES. 

What is the formula of a molecule of arsenum ? — In what form does 
arsenum occur in nature? — Describe the characters of white arsenic. 
Name the official preparations of arsenum. — What compound of arsenum 
is contained in Liquor Potassii Arsenitis, U. S. P., and in Liquor Acidi Arse- 
nosi, U. S. P.? — By what method may arsenic be reduced to arsenum ? — Give 
the formulae of arsenous and arsenic acids and anhydrides. — Explain, by 
diagrams, the reactions which occur in converting arsenic into sodium 
arsenate by the official process. — Why is anhydrous instead of crystal- 
lized sodium arsenate employed in the preparation of Liquor Sodii Arse- 
natis, U. S. P.? — In the preparation of ferrous arsenate from ferrous sul- 
phate and sodium arsenate why is sodium bicarbonate included? 
Describe the manipulations necessary to obtain arsenic in its characteristic 
crystalline form. — How is Eeinsch's test for arsenum applied? and under 
what circumstances may its indications be fallacious?— Give the details 
of Marsh's test for arsenum, and the precautions to be observed. — Explain 
the reactions by diagrams. — What peculiar value has Fleitmann's test 
for arsenum ? — Describe the conditions under which sulphuretted hydro- 
gen becomes a trustworthy test for arsenum. — How may a trace of 
arsenum sulphide be detected in sulphur ? — How are salts of copper and 
silver applied as reagents for the detection of arsenum ? — How are 
avsenites distinguished from arsenates? — Mention the best antidote in 
case of poisoning by arsenic ; explain the process by which it may be 
most quickly prepared, and describe its action. — Do you know of any 
other antidote to arsenic ? If so, describe the mode of administration. 



ANTIMONY. 

Symbol, Sb (Stibium). Atomic weight, 120. 

Source and Uses. — Antimony occurs in nature chiefly as sulphide, 
Sb 2 S 3 . The crude or black antimony of pharmacy is this native sul- 



180 THE METALLIC RADICALS. 

phide freed from impurities by fusion : it has a striated, crystalline, 
lustrous fracture ; subsequently powdered, and if it contains any 
soluble arsenum salt, the latter removed by digestion in solution of 
ammonia, it forms the grayish-black crystalline Antimonii Sul- 
phidum, Sulphide of Antimony, or Antimony Sulphide, U. S. P. 
The metal is obtained from the sulphide by roasting, the resulting 
oxide being reduced with charcoal and sodium carbonate. The 
resulting scoria is known as crocus of antimony or glass of antimony. 
Metallic antimony is an important constituent of tyjje-metal, Britan- 
nia metal (tea- and coifee-pots, spoons, etc.), and the best varieties 
of pewter. The old pocula emetica, or everlasting emetic cups, were 
made of antimony ; wine kept in them for a day or two was said to 
have acquired emetic quality. The metal is not used in making 
official antimonial preparations, the sulphide alone being, directly 
or indirectly, employed for this purpose. 

Antimony has very close chemical analogies with arsenum. Its 
atom, in the common salts, exerts trivalent activity (e. g. SbCl 3 ),but 
sometimes it is quinquivalent (e. g. SbCl 5 ). 

Antimony, like arsenum, unites with iodine to form a tri-iodide 
(Sbl 3 ). A bromide (SbBr 3 ) also is known. 

Reactions having Synthetical Interest. 
Antimonious Chloride, or Chloride of Antimony. 

First Synthetical Reaction. — Boil £ an ounce or less of antimony 
sulphide with four or five times its weight of hydrochloric acid in a 
dish placed in a fume-chamber or in the open air ; sulphuretted 
hydrogen is evolved and solution of antimony chloride, SbCl 3 , is 
obtained. 

Sb 2 S 3 -f 6HC1 = 2SbCl 3 + 3H 2 S 

Antimony Hydrochloric Antimony Sulphuretted 

sulphide. acid. chloride. hydrogen. 

This solution, cleared by subsidence, is what is commonly known 
as Butter of Antimony {Liquor Antimonii Chloridi, B. P.). If pure 
sulphide has been used in its preparation, the liquid is nearly color- 
less ; but much of that met with in veterinary pharmacy is simply a 
by-product in the generation of sulphuretted hydrogen from native 
ferruginous antimony sulphide and hydrochloric acid, and is more 
or less brown from the presence of iron chloride. It not infre- 
quently darkens in color on keeping : this is due to absorption of 
oxygen from the air and conversion of light-colored ferrous into 
dark-brown ferric chloride or oxychloride. 

True Butter of Antimony (SbCl 3 ) is obtained on evaporating the 
above solution to a low bulk and distilling the residue. The butter 
condenses as a white crystalline semi-transparent mass in the neck 
of the retort ; at the close of the operation it may be easily melted 
and run down into a bottle, which should be subsequently well 
stoppered. 

Antimony Pentachloride (SbCl 5 ), or Antimonic Chloride, is a fum- 
ing liquid, obtained on passing chlorine over the lower chloride. 



ANTIMONY. 181 

Antimonious Oxychloride, or Oxychloride of Antimony. 

Second Synthetical Reaction. — Boil the solution of antimony 
chloride produced in the last reaction, and pour it into several 
ounces of water ; a white precipitate of antimony oxychloride 
(2SbCl 3 ,5Sb 2 3 ) falls, some antimony chloride remaining in the 
supernatant acid liquid. 

This precipitate is the old pulvis Algarothi, pulvis angelicus, or 
mercurius vitce. It varies somewhat in composition, according to 
the amount of water with which the chloride may be mixed, but on 
standing under water gradually becomes crystalline, and has the 
composition above given. 

12SbCl 3 + 15H 2 = 2SbCl ? ,5Sb 2 3 + 30HC1 

Antimony Water. Antimony Hydrochloric 

chloride. oxychloride. acid. 

Antimonious Oxide, or Oxide of Antimony. 

Well wash the precipitate with water by decantation (vide 
p. 110), and add solution of sodium carbonate ; the chloride 
remaining with the oxide is thus decomposed, and antimony 
oxide (Sb 2 3 ) alone remains. This is Antimonii Oxidum, U. S. 
P. It is of a light buff or grayish-white color, or quite white 
if absolutely free from iron, insoluble in water, soluble in hydro- 
chloric acid, fusible at a low red heat. The moist antimony 
oxide may be well washed and employed for the next reaction. 
Or it may be dried over a water-bath, for at temperatures 
above 100° C. oxygen is absorbed and other antimony oxides 
formed. The presence of the latter is detected on boiling the 
powder in solution of acid potassium tartrate, in which antimony 
oxide (Sb 2 3 ; Sb 4 6 ?) is soluble, but antimonic anhydride 
(Sb 2 5 ) and the double oxide, or so-called antimonious anhydride 
(Sb 4 8 ), is insoluble. 

2SbCl ? ,5Sb a O, + 3Na 2 C0 3 = 6Sb 2 3 + 6NaCl + 3C0 2 

Antimony Sodium Antimony Sodium Carbonic 

oxychloride. carbonate. oxide. chloride. acid gas. 

The Higher Antimony Oxide (Sb 2 5 ), termed antimonic oxide 
or anhydride, corresponding with arsenic anhydride, is obtained 
on decomposing the pentachloride by water or on boiling 
metallic antimony with nitric acid. The variety obtained from 
the chloride differs in saturating power from that obtained from 
the metal, and is termed metantimonic acid Qxerd, meta, be- 
yond). 

Tartar Emetic. 

Third Synthetical Reaction. — Mix the moist antimony oxide 
obtained in the previous reaction with about an equal quantity 



182 THE METALLIC RADICALS. 

of cream of tartar (6 of the latter to 5 of the dry oxide) and 
sufficient water to form a paste ; set aside for a day to facilitate 
complete combination ; boil the product with water and filter ; 
the resulting liquid contains antimony and potassium tartrate 
(KSbOC 4 H 4 6 ), antimony potassio-tartrate, or tartarated anti- 
mony, or tartar emetic (emetic, from s/j.£id, emeo, I vomit; 
tartar, from Tdprapo?, tartaros ; see Index). 

2KHC 4 H 4 6 + SbA = 2KSbOC 4 H 4 6 + H 2 

Acid potassium Autiraony Tartar emetic. Water, 

tartrate. oxide. 

On evaporation, the salt is obtained in colorless, transparent tri- 
angular-faced crystals containing one molecular proportion of water 
to every two of anhydrous salt, forming the Tartrate of Antimony 
and Potassium, Antimonii et Potassii Tartras. U. S. P., or Antimony 
and Potassium Tartrate (KSbOC 4 H 4 6 ) 2 ,II 2 0. 

The formula for tartar emetic is apparently inconsistent with the 
general formula for tartrates (R / R / C 4 H 4 6 ) ; this will be subse- 
quently fully explained in connection with Tartaric Acid. The salt 
appears to be an oxytartrate, K / Sb /// // (C^O,.)". 

Tartar emetic is soluble in water, and slightly so in proof spirit. 
Dissolved in sherry wine, it forms the official Vinum Antimonii, 
U. S. P. It may be externally applied as an ointment, JJnguentum 
Antimonii Tartarati, B. P. 

"Sulphurated Antimony" and other Antimony 
Oxysulphides. 

Fourth Synthetical Reaction. — Boil a gramme or two of anti- 
mony sulphide with solution of soda in a test-tube, and filter 
(or larger quantities in larger vessels, 1 part of sulphide to 12 
of soda and 30 of water, for two hours, frequently stirring, 
and occasionally replacing water lost by evaporation). Into 
the filtrate, before cool, stir diluted sulphuric acid until the 
liquid is slightly acid to test-paper ; a reddish-brown precipi- 
tate, sulphurated antimony, is formed, Antimonium Sulphur atum, 
U. S. P. ; filter, wash, and dry over a water-bath. It is a mix- 
ture of antimony sulphide (Sb 2 S 3 ) with a little oxide (Sb 2 3 ). 
The oxide results from the double decomposition of antimony 
sulphide and caustic soda. 

This is one of the many varieties of mineral Jcermes, so called 
from their similarity in color to the insect kermes. Kermes is the 
name, now obsolete, of the Coccus Ilicis, a sort of cochineal insect, 
full of reddish juice, and used for dyeing from the earliest times. 
The term mineral kermes was apparently applied originally to the 
amorphous or precipitated orange antimony sulphide (Sb 2 S 3 ). It 
afterward included any oxysulphide and pentasulphide. The color 
of the brownish-red variety is affected by the temperature as well as 



ANTIMONY. 



183 



state of dilution of the alkaline liquid when the acid is added. 
When this alkaline liquid is boiled, especially if long exposed to air, 
oxygen is absorbed by some of the antimony, whose sulphur, uniting 
with the trisulphide, forms a portion of the lighter yellow penta- 
sulphide. The process of the British Pharmacopoeia includes the 
use of as much sulphur as black antimony sulphide ; the product is 
of an orange-red color and contains much antimony pentasulphide. 
Explanation of Processes. — Antimony sulphides and oxides, like 
those of arsenium, react with the sulphides, hydrates, and oxides of 
certain metals to form salts of greater or less degree of solubility. 
Thus, sodium antimonite (Na 3 Sb0 3 ) is formed and remains in solu- 
tion, and sodium sulphantimonite (Na 3 SbS 3 ) is formed, and is depos- 
ited in brilliant yellow tetrahedral crystals when a hot alkaline 
solution of antimony sulphide is set aside to cool. Sulphur being 
present, the slightly soluble sodium antimoniate (Na 3 SbOJ and 
sodium sulphantimoniate (Na 3 SbS 4 ) are produced. 



+ 



2Sb 2 S 3 

Antimony 
sulphide. 



Sb 2 3 -f 

Antimonious oxide. 



6NaHO = 2Na 3 SbS 3 + Sb 2 3 -f 

Soda. Sodium Antimonious 

sulphantimonite. oxide. 

6NaHO = 2Na 3 Sb0 3 + 3 

Sodium antimonite. 



3H 2 

Water. 



2Sb 2 S 3 + 2S 2 + 6NaHO = 2Na 3 SbS 4 + Sb 2 5 + H 2 + 2H 2 S 

Antimony Sodium Antimonic 

sulphide. sulphantimoniate. oxide. 



Sb 2 5 + 

Antimonic oxide. 



sulphantimoniate. 

6NaHO =" 2Na 3 Sb0 4 + 

Sodium antimoniate. 



3H 2 



In the hot solutions of these sulphur salts and oxygen salts, anti- 
mony sulphides and oxides are soluble, and are reprecipitated in an 
indefinite state of combination, partially on cooling or wholly on the 
addition of acid. The acid also decomposes the oxysalts with pre- 
cipitation of oxides, and the sulphur salts with precipitation of 
sulphides of antimony. The acid should be added to the liquids 
before much oxysulphide has deposited (that is, before the solution 
is cool) if uniformity of product is desired. 



2Na 3 SbS 3 + 

Sodium 
sulphantimonite. 

2Xa 3 Sb0 3 + 

Sodium antimonite. 



3H 2 S0 4 = 3Na ? S0 4 

Sulphuric Sodium 

acid. sulphate. 

3H 2 S0 4 = 3Na ? S0 4 

Sulphuric Sodium 

acid. 



2Na 3 SbS 4 

Sodium 
sulphantimoniate 

2Na 3 Sb0 4 

Sodium 
antimoniate. 



+ 



+ 



3H 2 S0 4 = 

Sulphuric 
acid. 

3H 2 SCV = 

Sulphuric 
acid. 



sulphate. 

3Na 2 S0 4 

Sodium 
sulphate. 

3Na 2 S0 4 

Sodium 
sulphate. 



+ Sb 2 S 3 

Antimonious 
sulphide. 

+ Sb 2 3 

Antimonious 
oxide. 

+ Sb 2 S 5 

Antimonic 
sulphide. 



+ 



+ 



Sulphuretted 
hydrogen. 

3H 2 

Water. 



+ 



Antimonic 
oxide. 



+ 



+ 



3H 2 S 

Sulphuretted 
hydrogen. 

3H 2 

Water. 



The oxides and sulphides indicated in these equations, together 
with excess of antimony sulphide originally dissolved by the alka- 
line liquid, are all precipitated when the acid is added, and form 



184 THE METALLIC RADICALS. 

the varieties of kermes. Kermes may be formed by fusion as well as 
by aqueous solution of the components. The student is strongly 
recommended carefully to study the foregoing paragraphs ; for, 
although neither the official nor any other variety of kermes is itself 
of much importance in modern practical pharmacy, a thoughtful 
consideration of their chemistry will, by revealing chemical actions 
and analogies that are general, aid in sowing the germs of chemical 
principles in the mind, 



The previous four synthetical reactions illustrate the official process 
for the respective substances. In pharmacy the solution of antimony 
chloride is only used in the preparation of oxide ; the oxide, besides 
its use in the preparation of tartar emetic, is mixed with twice its 
weight of calcium phosphate (purified bone-earth) to form Pulvis 
Antimonialis, U. S. P., or "James's Powder." 

Antimony Sulphides and Hydrides are incidentally mentioned in 
the following analytical paragraphs. 



Reactions having Analytical Interest (Tests). 

First Analytical Reaction. — Through an acidified antimonial 
solution pass sulphuretted hydrogen ; an orange precipitate 
(amorphous antimony sulphide) falls. It has the same compo- 
sition as the crystalline black sulphide (Sb 2 S 3 ), into which, 
indeed, when dried, it is quickly converted by heat. Like 
arsenum sulphide, it is soluble in alkaline solutions. Collect a 
portion on a filter, and, when well drained, add strong hydro- 
chloric acid ; it dissolves — unlike arsenum sulphide. 

A higher antimony sulphide (Sb 2 S 3 ), corresponding to the 
higher arsenum sulphate, exists. It is formed on passing 
sulphuretted hydrogen through an acidified solution of the 
higher chloride (SbCl 5 ), or less pure, on boiling black antimony 
sulphide and sulphur with an alkali and decomposing the re- 
sulting filtered liquid by an acid. 

Note. — The arsenous and antimonious compounds are those 
chiefly employed in medicine ; sodium and iron arsenates are, how- 
ever, sometimes employed. The arsenates, and rarely, an anti- 
moniate, are useful in analysis, and the antimonic chloride in 
chemical research. The higher compounds of both elements are 
noticed here' chiefly to draw attention to the close analogy existing 
between arsenum and stibium — an analogy carried out in the 
numerous other compounds of these elements. 

Second Analytical Reaction. — Dilute two or three drops of 
the solution of antimony chloride with water ; a white precipi- 
tate (oxychloride) occurs, the formation of which has been 



ANTIMONY. 185 

explained under the similar synthetical reaction. The occur- 
rence of a precipitate under the circumstances distinguishes 
antimony from arsenum, but is a reaction that cannot be fully 
relied upon in analysis, because requiring the presence of too 
much material and the observance of too many conditions. Add 
a sufficient quantity of hydrochloric acid to dissolve the pre- 
cipitate, and boil a piece of copper in the solution, as directed 
in the corresponding test for arsenum (vide p. 172) ; antimony 
is deposited on the copper. Wash, dry, and heat the copper in 
a test-tube, as before ; the antimony, like the arsenum, is vola- 
tilized off the copper, and condenses on the side of the tube as 
white oxide ; but the sublimate, from its low degree of vola- 
tility, condenses close to the copper ; moreover, it is destitute 
of crystalline character. 

Shake out the copper and boil water in the tube for several 
minutes. Do the same with the arsenical sublimate similarly 
obtained. The deposit of arsenic slowly dissolves, and may 
be recognized in the solution by silver ammonio-nitrate ; the 
antimonial sublimate is insoluble. 

Third Analytical Reaction. — Perform the experiments de- 
scribed under Marsh's test for arsenum (p. 173), carefully 
observing all the details there mentioned, but using a few 
drops of solution of antimony chloride or tartar emetic instead 
of the arsenical solution. Antimoniuretted hydrogen, or anti- 
mony hydride (SbH 3 ), is formed and decomposed in the same 
way as arseniuretted hydrogen. 

To one of the arsenum spots on the porcelain lid (p. 173) 
add a drop of solution of " chloride of lime " (bleaching-pow- 
der) ; it quickly dissolves. Do the same with an antimony 
spot ; it is unaffected. Heat more quickly causes the volatili- 
zation of an arsenum than an antimony spot; ammonium 
sulphydrate more readily dissolves the antimony than the 
arsenum. 

Boil water for several minutes in the beaker or wide test- 
tube containing the arsenous sublimate (p. 173) ; it slowly 
dissolves, and may be recognized in the solution by the yellow 
precipitate given on the addition of solution of silver ammonio- 
nitrate. The antimonial sublimate, similarly treated, does not 
dissolve. 

Pass a slow current of sulphuretted hydrogen through the 
delivery-tube removed from the hydrogen apparatus (p. 173), 
and when the air may be considered to have been expelled 
from the tube, gently heat that portion containing the deposit 
of arsenum : the latter will be converted into a yellow subli- 
mate of arsenum sulphide. Remove the tube from the sul- 



186 THE METALLIC RADICALS. 

phuretted-hydrogen apparatus, and repeat the experiment with 
a similar antimony deposit : it is converted into oranye anti- 
mony sulphide, which, moreover, owing to inferior volatility, 
condenses nearer to the flame than arsenum sulphide. 

Pass dry hydrochloric acid gas through the two delivery- 
tubes. This is accomplished by adapting first one tube and 
then the other by a cork to a test-tube containing a few lumps 
of common salt on which a little sulphuric acid is poured 
during the momentary removal of the cork. The antimony 
sulphide dissolves and disappears ; the arsenum sulphide is 
unaffected. 

Thorough perception of the chemistry of arsenum and antimony 
will be obtained on constructing equations or diagrams descriptive of 
each of the foregoing reactions. 

Antidote. — The introduction of poisonous doses of antimo- 
nials into the stomach is fortunately quickly followed by 
vomiting. If vomiting has not occurred or apparently to an 
insufficient extent, any form of tannic acid may be adminis- 
tered (infusion of tea, nutgalls, cinchona, oak-bark, or other 
astringent solutions or tinctures), an insoluble antimony tan- 
nate being formed, and absorption of the poison consequently 
somewhat retarded. The stomach-pump or stomach -siphon 
must be applied as quickly as possible. 

Recently precipitated moist ferric hydrate is also, according 
to T. and H. Smith, a perfect absorbent of antimony from its 
solutions, the chemical action being probably, they say, similar 
to that which takes place between ferric hydrate and arsenous 
anhydride. It may be given in the form of a mixture of 
ferric chloride with either sodium carbonate or other soluble 
carbonate or bicarbonate, or with magnesia. 

These statements may be verified by mixing together the 
various substances, filtering, and testing the filtrate for anti- 
mony in the usual manner. 



DIRECTIONS FOR APPLYING THE FOREGOING REACTIONS TO THE 
ANALYSIS OF AN AQUEOUS SOLUTION OF A SALT OF ONE 
OF THE ELEMENTS ARSENUM AND ANTIMONY. 

Acidify the liquid with hydrochloric acid, and pass through 
it sulphuretted hydrogen : 

A yellow precipitate indicates arsenum ; 

An orange precipitate indicates antimony. 

The result may be confirmed by the application of other 
tests. 



ANTIMONY. 187 

DIRECTIONS FOR APPLYING THE FOREGOING REACTIONS TO THE 
ANALYSIS OF AN AQUEOUS SOLUTION OF SALTS OF BOTH 
ARSENUM AND ANTIMONY. 

Acidify a small portion of the liquid with hydrochloric acid, 
and pass through it sulphuretted hydrogen. 

Note 1. — If the precipitate by sulphuretted hydrogen is unmis- 
takably orange, antimony may be put down as present, and arsenum 
only further sought by the application of Fleitmann's test to the 
solution of the sulphides in aqua regia* freed from sulphur by 
boiling, or, better, to the original solution. 

Note 2. — Antimony sulphide is far less readily soluble than arse- 
num sulphide in solution of ammonium carbonate. But this fact 
possesses limited analytical value ; for the color of the sulphides is 
already sufficient to distinguish the one from the other when they 
are unmixed ; and when mixed, much antimony sulphide will pre- 
vent a little arsenum sulphide from being dissolved by the alkaline 
carbonate, while much arsenum sulphide will carry a little anti- 
mony sulphide into the solution. When the proportions are, appa- 
rently, from the color of the precipitate, less wide, solution of 
ammonium carbonate will be found useful in roughly separating 
the one sulphide from the other. On filtering and neutralizing the 
alkaline solution by an acid the yellow arsenum sulphide is repre- 
cipitated. The orange antimony sulphide will remain on the filter. 

Note 3. — Solution of potassium bisulphite is said by Wbhler to 
he a good reagent for separating the sulphides of arsenum and 
antimony, the former being soluble, the latter insoluble, in the 
liquid. 

Note 4- — Another reagent for separating the sulphides of arse- 
num and antimony is strong hydrochloric acid. As little water as 
possible must be present. On boiling, antimony sulphide dissolves, 
while arsenum sulphide remains insoluble. The liquid, slightly 
diluted, filtered, more water added, and sulphuretted hydrogen again 
transmitted, gives orange antimony sulphide. The process should 
previously be tried on the precipitated mixed sulphides. The pres- 
ence of arsenum may be confirmed by the application of Fleitmann's 
test to the original solution. 

Note 5. — If the precipitate by sulphuretted hydrogen is unmis- 
takably yellow, arsenum may be put down as present, and any 
antimony be detected by the previous or one of the following two 
processes. These two processes are rather long, and require much 
care in their performance, but are useful, because a small quantity 
of antimony in much arsenum, or vice versa, may be detected by 
their means. 

First Process. — Generate hydrogen, and pass it through a 

* Aqua Eegia is a mixture of 4 parts hydrochloric and 3 parts nitric 
acid. It was so called from its property of dissolving gold, the "king" 
of metals. Diluted with rather more than four times its bulk of water, 
it forms the Aciclum Nitro-hydrochloricum Dilutum, B. P. 



188 THE METALLIC RADICALS. 

small wash-bottle containing solution of lead acetate, to free 
the gas from any trace of sulphuretted hydrogen it may pos- 
sess, and then through a dilute solution of silver nitrate con- 
tained in a test-tube. When the apparatus is in good working 
order, pour into the generating-bottle the solution to be exam- 
ined, adding it gradually to prevent violent action. After the 
gas has been passing for five or ten minutes examine the con- 
tents of the silver nitrate tube ; arsenum, if present, will be 
found in the solution in the state of arsenous acid — 

AsH 3 + 3H 2 + 6AgN0 3 = H 3 As0 3 + 6HN0 3 -f 3Ag 2 ; 

while antimony, if present, will be found in the black precipi- 
tate that has fallen, according to the following equation ; 

SbH 3 + 3AgN0 3 = SbAg 3 + 3HN0 3 . 

The arsenous radical may be detected in the clear, filtered 
supernatant liquid, which still contains much silver nitrate, by 
cautiously neutralizing with a very dilute solution of ammo- 
nia, or by adding a few drops of solution of silver ammonio- 
nitrate, yellow silver arsenite being produced. The anti- 
mony may be detected by washing the black precipitate, 
boiling it in an open dish with solution of tartaric acid, acidulat- 
ing with hydrochloric acid, filtering and passing sulphuretted 
hydrogen through the solution, the orange sulphide being 
precipitated (Hofmann). 

Second Process. — Obtain the metallic deposit in the middle 
of the delivery-tube, as already described under Marsh's test. 
Act on the deposit by sulphuretted hydrogen gas, and then by 
hydrochloric acid gas, as detailed in the third analytical reac- 
tion of antimony (p. 186). If both arsenum and antimony 
are present, the deposit, after the action of sulphuretted hydro- 
gen, will be found to be of two colors, the yellow arsenum sul- 
phide being usually farther removed from the heated portion 
of the tube than the orange antimony sulphide. Moreover, 
subsequent action of hydrochloric acid gas causes disappear- 
ance of the antimonial deposit, which is converted into anti- 
mony chloride and carried off in the stream of gas. 

The chief objection to this process is the liability of the operator 
mistaking sulphur, deposited from the sulphuretted hydrogen gas 
by heat, for arsenum sulphide. But the presence or absence of 
arsenum is easily confirmed by applying Fleitmann's test to the 
original solution, while the process is most useful for the detection 
of a small quantity of a salt of antimony when mixed with much 
arsenical matter. On the whole, Hofmann's method is to be recom- 
mended. 



COPPER. 189 

The laboratory student may now proceed to the analysis of 
aqueous solutions of salts of any of the metallic elements hitherto 
considered. The method followed may be that for the separation of 
the previous three groups, sulphuretted hydrogen being first passed 
through the solution to throw out arsenum and antimony. The 
whole scheme of analysis is given in the accompanying table, p. 190. 
Three or four solutions should be examined before proceeding to the 
next and last group of metals. 

Learners who have no opportunity of working at practical analy- 
sis will gain much knowledge by endeavoring, not to remember, 
but to understand, these methods of separating elements from each 
other in a solution containing several compounds. 



QUESTIONS AND EXEECISES. 

What is the composition and source of "black antimony"? — In what 
alloys is metallic antimony a characteristic ingredient ? — What is the 
quantivalence of antimony as far as indicated by the formulae of the offi- 
cial preparations ? — By a diagram show how "butter of antimony" is 
prepared. — Write out equations or diagrams expressive of the reactions 
which occur in converting antimony chloride into oxide. — What is the 
formula of tartar emetic? — Explain the preparation of antimony oxysul- 
phide {Antimonium Sulphuratum, U. S. P.) by aid of diagrams. — Give a 
comparative statement of the tests for arsenum and antimony.— How is 
antimony detected in the presence of arsenum?— How may arsenum 
and iron be distinguished analytically? — Describe a method by which 
antimony, magnesium, and iron may be separated from each other.— 
Draw out a chart for the analysis of an aqueous liquid containing salts 
of arsenum, zinc, calcium, and ammonium. 



COPPER, MERCURY, LEAD, SILVER. 

These metals, like arsenum and antimony, are precipitated from 
acidified solutions by sulphuretted hydrogen in the form of sul- 
phides, but the sulphides, unlike those of arsenum and antimony, are 
soluble in alkalies. The atom of copper is usually bivalent, Cu"; 
mercury bivalent in the mercuric salts, Hg // , and univalent in the 
mercurous salts, Hg'; lead sometimes quadrivalent, Pb //// , but gen- 
erally exerting only bivalent activity, Pb"; and silver univalent, Ag'. 

COPPER. 

Symbol, Cu. Atomic weight, 63.3. 

Source — The commonest ore of this metal is copper pyrites, a 
double copper and iron sulphide raised in Cornwall ; Australia and 
Russia supply malachite; a mixed carbonate and hydrate ; much ore 
is also imported from Spain and from South America. It is smelted 
in enormous quantities at Swansea, South Wales, a locality pecu- 
liarly fitted for the operation on account of its proximity to the coal- 
fields and its position as a seaport, these united advantages ensur- 
ing cheap fuel and freightage to the different metallurgical estab- 
9* 



190 



THE METALLIC RADICALS. 






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COPPER. 191 

lishments. By Hollway's economical method of smelting copper 
pyrites and other sulphides, after the sulphide is once melted air is 
driven, not over, as usual, but through the mass ; the combustion of 
the sulphur then becomes self-supporting, and is greatly accelerated. 

Alchemy. — The alchemists termed this metal Venus, perhaps on 
account of the beauty of its lustre, and gave it her symbol 9 , a com- 
pound hieroglyphic also indicating a mixture of gold, 0, and a cer- 
tain hypothetical substance called acrimony, »•£•, the corrosive nature 
of which was symbolized by the points of a Maltese cross. To this 
day the blue show-bottle in the shop-window of the pharmacist is 
occasionally ornamented by such a symbol, indicating, possibly, 
that the blue liquid in the vessel is a preparation of copper. 

Coinage. — The material of the British "copper" coinage is now a 
bronze mixture, composed, in 100 parts by weight, of 95 copper, 4 
tin, and 1 zinc, the same as in the copper coinage of France. The 
penny is coined at the rate of 48 pence in 1 pound avoirdupois of 
7000 grains, or 453.6 grammes ; the halfpenny at 80 in the pound 
avoirdupois, and the farthing at 160. These British bronze coins or 
tokens are a legal tender in payments to the amount of Is. 

Metallic Copper, U. S. P. {Cuprum, B. P.) is in the form of fine 
wire, about No. 25 of the Birmingham wire gauge, or 0.02 of an 
inch in diameter, and is used in preparing Spiritus JEtheris Nitrosi, 
B. P., or in the form of "pure metallic copper, thin and bright" 
{Copper-foil, B. P.). 

Quantivalence. — Copper forms two classes of salts ; in one the 
atom is bivalent (Cu // ), in the other it exerts univalent activity 
(Cu'). The former are of primary importance to the student, the 
latter being for the most part unstable and wanting in technical 
interest. Their compounds are distinguished as cupric and cuprous. 
Cuprous iodide (Cu 2 I 2 ) will be subsequently referred to as a con- 
venient form in which to remove iodine from solution, while the for- 
mation of cuprous oxide (Cu 2 0) under given circumstances will 
come under notice as an indicator of the presence of sugar in a 
liquid. 

Reactions having Synthetical Interest. 
The processes for the following salts include the only syn- 
thetical reactions having any medical or pharmaceutical inter- 
est : (1) cupric oxide, black copper oxide, prepared by heating 
fragments of copper to low redness on a piece of earthenware 
in an open fire ; (2) cupric sulphate, the common copper sul- 
phate, prepared by boiling black oxide and about an equal 
weight of sulphuric acid in water, filtering and setting aside 
the solution, so that crystals may form on cooling ; and (3) cop- 
per ammonio-sulphates, for the preparation of which see pp. 
177-193. 

Cu 2 + 2 = 2CuO 

Copper. Oxygen. Cupric oxide. 

CuO + H 2 S0 4 = CuS0 4 + H 2 

Cupric oxide. Sulphuric acid. Cupric sulphate. Water. 



192 THE METALLIC RADICALS. 

Copper Sulphate. 

Synonyms. — Sulphate of Copper ; Cupric Sulphate : Blue Vitriol ; 
Blue Stone. 

Copper Sulphate (Cupri Sulphas , U. S. P., CuS0 4) 5H 2 0) is the 
only copper salt much used in pharmacy. It is a by-product in sil- 
ver-refining (2Ag 2 S0 4 + Cu 2 = 2CuS0 4 + 2Ag 2 ). A little is formed 
in roasting copper pyrites. In the latter case some ferrous sul- 
phide and copper sulphide are oxidized to sulphates ; but the low 
red heat finally employed decomposes ferrous sulphate, while copper 
sulphate is unaffected 5 it is purified by crystallization from a hot 
aqueous solution, though frequently much ferrous sulphate remains 
in the crystals. Copper sulphate results on dissolving in diluted 
sulphuric acid the black oxide (CuO) obtained in annealing copper 
plates (see the foregoing equation) ; it may also be prepared by boil- 
ing copper with three times its weight of sulphuric acid (2H 2 S0 4 -f- 
Cu = GuS0 4 + S0 2 -f- 2H 2 0), diluting, filtering, evaporating and 
crystallizing. In this process a little black copper sulphide is 
formed. 

Anhydrous Sulphate of Copper, B. P. (CuS0 4 ), is a yellowish- 
white powder prepared by depriving the ordinary blue crystals of 
copper sulphate of their water of crystallization by exposing to 
a temperature of about 200° C. It is used in testing alcohol and 
similar spirituous liquids for water, becoming blue if the latter be 
present. 

Nitrate of Copper (Cupri Nitras, B. P.), copper nitrate or cupric 
nitrate. Digest copper in diluted nitric acid. "When action has 
ceased, evaporate and crystallize. If the crystals form at a tem- 
perature of 73° to 80° F., they are prismatic and trihydrous, 
Cu(N0 3 ) 2 3H 2 ; at lower temperatures, tabular and hexahydrous, 
Cu(N0 3 ) 2 ,6H 2 0. 

3Cu 2 + 16HNO, + 10H 2 O = 6Cu(N0 3 ) 2 ,(H 2 0) 3 + 4NO. 

Copper. Nitric acid. Water. Copper nitrate. Nitric oxide. 

Verdigris (from verdi-gris, Sp., green-gray) is a subacetate or 
oxyacetate of copper (B. P.) (Cu 2 02C 2 H 3 2 ), obtained by exposing 
alternate layers of copper and fermenting refuse grape-husks to the 
action of air. Digested with twice its weight of acetic acid and a 
little water, the mixture being evaporated to dryness and the residue 
dissolved in water, it forms the official (B. P.) solution of acetate of 
copper (Cu2C 2 H,0 2 ). 

The modes of forming Cupric Sulphide, Hydrate, Oxide, Ferro- 
cyanide and Arsenite, as well as Metallic Copper, are incidentally 
alluded to in the following analytical paragraphs. 

Eeactions having Analytical Interest (Tests). 

First Analytical Reaction— Pass sulphuretted hydrogen 
through an acidified solution of a copper salt (sulphate, for 
example) ; a black precipitate (cupric sulphide, CuS) falls. 

Second Analytical Reaction. — To an aqueous copper solution 



COPPER. 1 93 

add ammonium sulphydrate ; by this reagent also cupric sul- 
phide is precipitated, insoluble in excess. 

Note. — Cupric sulphide is not altogether insoluble in ammonium 
sulphydrate if free ammonia or much ammoniacal salt be present ; 
it is quite insoluble in the fixed alkaline sulphydrates. 

Third Analytical Reaction. — Immerse a piece of iron or 
steel, such as the point of a penknife or a piece of wire, in a 
few drops of copper solution ; the copper is deposited of cha- 
racteristic color, an equivalent quantity of iron passing into 
solution. By this reaction copper may be recovered on the 
large scale from waste solutions, old hoop or other scrap iron 
being thrown into the liquors. 

Note. — This reaction furnishes another illustration of direct chem- 
ical substitution. As a matter of fact, 56 parts of the iron displace 
63.3 of copper. As a matter of theory, in the whole mass of copper 
sulphate each of the (theoretical) ultimate particles or atoms of cop- 
per, weighing 63.3, is displaced by, or substituted by, one of the 
(theoretical) ultimate particles or atoms of iron, weighing 56, in the 
mass of iron. Why should the fact be as stated ? We do not know, 
but the best — nay, the only — suggested explanation is thaf by Dal- 
ton, the one just applied — namely, " the atomic theory," the theory 
that matter is not infinitely divisible, but composed of finite particles 
conveniently termed atoms. Just as the bricks in a house might be 
displaced, one by one, by similarly shaped pieces of stone, without 
the structure, qu£l structure or architecture, being altered, so the 
copper atoms in the chemical structure termed copper sulphate may 
be displaced, one by one, by iron atoms, the essential structure (at 
first CuS0 4 , afterward FeS0 4 ) not being altered. (In this particular 
case some other buildings or wings — namely, 2H 2 — are added to 
the structure at the same time, but this need not complicate the lead- 
ing idea just offered.) 

Fourth Analytical Reaction. — Add ammonia to a cupric solu- 
tion ; cupric hydrate (Cu2HO) of a light blue color is precip- 
itated. Add excess of ammonia ; the precipitate is redissolved, 
forming a blue solution of copper ammonio-salt, so deep in color 
as to render ammonia an exceedingly delicate reagent for this 
metal. 

A copper ammonio-sulphate may be obtained in large crystals by 
adding strongest solution of ammonia to powdered copper sulphate 
until the salt is dissolved, placing the liquid in a test-glass or cylin- 
der, cautiously pouring in twice its volume of strong alcohol or 
methylated spirit, taking care that the liquids do not become mixed, 
tying over the vessel with bladder, and setting aside for some weeks 
in a cool place (Wittstein). The constitution of copper ammonio- 
sulphate and other ammonio-salts and corresponding salts of silver 
will be alluded to in connection with " white precipitate," the official 
" ammoniated mercury." 



194 THE METALLIC RADICALS. 

Fifth Analytical Reaction. — Add solution of potash or soda 
to a cupric solution ; cupric hydrate (Cu2HO) is precipitated, 
insoluble in excess. Boil the mixture in the test-tube ; the 
hydrate is decomposed, losing the elements of water and becom- 
ing the black anhydrous oxide (CuO). 

Sixth Analytical Reaction. — Add solution of potassium ferro- 
cyanide (K 4 Fcy) to an aqueous cupric solution ; a reddish- 
brown precipitate (cupric ferrocyanide, Cu 2 Fcy) falls. This is 
an extremely delicate test for copper. 

Note. — Of course this reaction, like most chemical reactions, offers 
a case of chemical substitution (four univalent atoms of potassium, 
K 4 , by two bivalent atoms of copper, Cu 2 ) ; it only is not quite so 
direct as that of the third reaction. 

Seventh Analytical Reaction. — To a cupric solution add solu- 
tion of arsenic and cautiously neutralize with alkali ; green 
cupric arsenite (CuHAs0 3 ) falls. 

Note. — This precipitate has been mentioned already under Arse- 
num. An arsenum salt is thus a test for copper, as a copper salt 
is for arsenum — a remark that may obviously be extended to most 
analytical reactions, for the body acted upon characteristically by a 
reagent is as good a test for the reagent as the reagent is for it ; 
indeed, it becomes a reagent when the other body is the object of 
search. 

Most copper salts color flame green, the chloride blue. 

Antidotes. — In cases of poisoning by compounds of copper, 
iron filings should be administered, the action of which has 
just been explained. (See Third Analytical Reaction.) Potas- 
sium ferro-cyanide may also be given. (See Sixth Analytical 
Reaction.) Albumen forms with copper a compound insoluble 
in water ; hence raw eggs should be swallowed, vomiting being 
induced or the stomach-pump or stomach-siphon applied as 
speedily as possible. 



QUESTIONS AND EXEECISES. 

What are the analytical relations of copper, mercury, lead, and silver 
to each other and to arsenum and antimony? — Name the sources of 
copper. — What proportion of copper is contained in English and French 
''copper" coins? — Give diagrams showing how copper sulphate is pre- 
pared on the small and large scales. — Work out a sum showing how 
much crystallized copper sulphate may be obtained from 100 parts of 
sulphide. Ans. 261?. — How may copper oxide be prepared? — Mention 
the formula of verdigris. — Name a good chemical test for copper — What 
is the analytical position of copper ? — Mention the chief tests for copper. 
— How may copper be separated from arsenum? — Why is finely-divided 
iron an antidote in poisoning by copper ? 



MERCURY. 195 

MERCURY. 

Symbol, Hg. Atomic weight, 200. 

Molecular weight, 200 (not double the atomic weight). 

Source. — Mercury occurs in nature as sulphide (HgS), forming 
the ore cinnabar (an Indian name expressive of something red), 
and is obtained from Spain, California, Eastern Hungary, China, 
Japan, and Peru. 

Preparation. — The metal is separated by roasting off the sulphur 
and then distilling, or, better, distilling with lime, which combines 
with and retains the sulphur. 

Properties. — Mercury {Hydrargyrum, U. S. P.) is a silver-white, 
lustrous metal, liquid at common temperatures. It boils at 662° F., 
and at —40° F. solidifies to a malleable mass of octahedral crystals. 
When quite free from other metals it does not tarnish, and its glob- 
ules roll freely over a sheet of white paper without leaving any 
streak or losing their spherical form. 

Formula. — The formula of the mercury molecule is Hg, and not 
Hg 2 , because (at all events at the high temperature at which alone 
the weight of its vapor can be determined) two volumes, which, if 
hydrogen would weigh 2 parts (H 2 ) or oxygen 32 parts (0 2 ), in the 
case of mercury vapor weigh only 200 parts (Hg) ; that is, only 
once the atomic weight, not twice. That 200, and not 100, is the 
atomic weight of mercury, is shown by the fact that 200 is the 
minimum proportion, relative to 1 of hydrogen, in which mercury 
combines, and by its relation to heat. Still, it is difficult to imagine 
an atom existing in a free state in nature ; and the suggestion has 
been made that (as is proved to be the case with sulphur) mercury, 
as we know it, is in an abnormal condition, and that if the weight 
of its vapor could be taken at a lower temperature or under some 
other conditions, its molecular weight might be found to be 400. 
Similar remarks may be made respecting zinc and cadmium, the 
molecular weights of which, so far as we know, are identical with 
their atomic weights. At a very high temperature the weight of 
the vapor of iodine indicates a uniatomic molecule (I), at less ele- 
vated temperature two atoms in the molecule (I 2 ) — a fact strongly 
supporting the inference that the real molecular weight of mercury 
is 400. 

Medicinal Compounds. — The compounds of mercury used in 
medicine are all obtained from the metal. The metal itself, rubbed 
with chalk or with confection of roses and powdered liquorice-root, 
or with lard and suet, until globules are not visible to the unaided 
eye, is often used in medicine. The preparations are : the Hydrar- 
gyrum cum Creta, U. S. P., or "gray powder;" Massa Hydrargyria 
U. S. P., or "blue pill;" and Unguentum Hydrargyria U. S. P., or 
" blue ointment." There is also a compound ointment, a plaster of 
mercury, a plaster of ammoniacum and mercury, a liniment, and a 
suppository. Their therapeutic effects are probably due, not to the 
large quantity of metallic mercury in them, but to the small quan- 
tities of black and red oxide which occur in them through the 
action of the oxygen of the air on the finely-divided metal. The 



196 THE METALLIC RADICALS. 

proportion of oxide or oxides varies according to the age of the 
specimen. All these medicinal preparations of metallic mercury 
are indefinite and unsatisfactory, and that through no fault of the 
pharmacist. They much need investigation by pharmacologists 
and therapeutists. Here, as in many similar cases, if Medicine 
would first ascertain her own requirements, and then make them 
known, her handmaid Pharmacy would be found to be quite capable 
of supplying them. 

Mercurous and Mercuric Compounds. — Mercury combines with 
other elements and radicals in two proportions : those compounds 
in which the acidulous radicals are in the lesser amount are termed 
mercurous, the higher being mercuric. Thus calomel (HgCl) * is 
mercurous chloride, while corrosive sublimate (HgCl 2 ) is mercuric 
chloride. In every pair of mercury compounds the mercuric con- 
tains twice as much complementary radical, in proportion to the 
mercury, as the mercurous. 

Notes on Nomenclature. — The remarks made concerning the two 
classes of iron salts, ferrous and ferric (p. 143), apply in the main 
to the two series of mercury salts. The latter are systematically 
distinguished in most modern works by the terms mercurous and 
mercuric. But the alteration of the names of well-known sub- 
stances in medicine and pharmacy, especially if they are poisonous 
substances, is liable to be attended by serious consequences to 
patients ; therefore in the British and United States Pharmaco- 
poeias, which include only a few in comparison with the whole 
number of mercury salts, older and more strongly contrasted names 
are employed, thus : 

Systematic Names. Official Names. 

Mercurous iodide . . Yellow mercurous iodide. 

Mercuric iodide . . . Red mercuric iodide. 

Mercurous nitrate . . Not mentioned. 

Mercuric nitrate . . Mercuric nitrate. 

Mercurous sulphate . Not mentioned. 

Mercuric sulphate . Basic mercuric sulphate. 

Mercurous chloride . Mild mercurous chloride. 

Mercuric chloride . . Corrosive mercuric chloride. 

Mercurous oxide . . Not mentioned. 

fur • •, f Red mercuric oxide, or red precipitate. 

Mercuric oxide . . 1 -tr n • -j n • *i. ± 

{ Yellow mercuric oxide, or yellow precipitate. 

Specific Gravity . — Mercury is 13.6 times as heavy as water. 

Amalgams. — The compound formed on fusing metals together is 
usually termed an alloy (ad and ligo, I bind), but if mercury is a 
constituent, an amalgam (fidla-y/ua, malagma, from fialdcao, malasso, 
I soften, the presence of mercury lowering the melting-point of 
such a mixture). Most metals, even hydrogen, according to Loew, 
form amalgams. " Electric amalgam " consists of 1 part each of 
tin and zinc and 3 parts mercury. 

* The specific gravity of the vapor of calomel, and the fact that the 
salt is not decomposed at the temperature at which its specific gravity is 
taken, indicate that the formula of calomel is HgCl, and not Hg2Cl2. 



MERCURY. 197 

Reactions having Synthetical Interest. 

The Two Iodides. 

First Synthetical Reaction. — Rub together a small quantity 
of mercury and iodine, controlling the rapidity of combination 
by adding previously, and afterward occasionally, a few drops 
of spirit of wine, which by evaporation absorbs heat and thus 
keeps down the temperature. The product is either mercuric 
iodide, mercurous iodide, or a mixture of the two, as well as 
mercury or iodine if excess of either has been employed. If 
the two elements have been previously weighed in single atomic 
proportions, 200 of mercury to 127 of iodine (about 8 to 5, or 
1 ounce of mercury to 278 grains of iodine), the mercurous or 
greenish (grayish-green) iodide results (Hgl) ; if in the pro- 
portion of one atom of mercury to two atoms of iodine (200 
to twice 127, or about 4 to 5), the mercuric or red iodide, 
Hgl 2 , results — an iodide that is official, but made in another 
way (see p. 198). The mercurous iodide should be made and 
dried (without heat) with as little exposure to light as possible. 
Red iodide may be removed from it by well washing with alco- 
hol, and, if pure, the mercurous iodide is yellow. 

Mercurous iodide is decomposed slowly by light, and quickly by 
heat, into mercuric iodide and mercury. Mercuric iodide occurring 
as an impurity in mercurous iodide may be detected by digesting in 
ether (in which mercurous iodide is insoluble), filtering, and evap- 
orating to dryness ; mercuric iodide remains. Mercuric iodide is 
stable, and may be sublimed in scarlet crystals without decomposi- 
tion. (For the mechanical details of the method by which a speci- 
men of the crystals may be obtained, and the precautions to be 
observed, vide "Corrosive Sublimate," p. 202.) 

Relation of Mercuric Iodide to Light. — In condensing, mercuric 
iodide is at first yellow, afterward acquiring its characteristic scarlet 
color. This may be shown by smearing or rubbing a sheet of white 
paper with the red iodide, and then holding the sheet before a fire 
or over a flame for a few seconds. As soon as the paper becomes 
hot the red instantly changes to yellow, and the salt does not quickly 
regain its red color, even when cold, if the paper is carefully handled. 
But if a mark be made across the sheet by anything at hand, or the 
salt be pressed or rubbed in any way, the portions touched imme- 
diately return to the scarlet condition. According to Warington, 
this change is consequent upon rhomboidal crystals being converted 
into octahedra with a square base, and will serve as an excellent 
illustration of the influence of physical structure in causing 
color. The yellow modification so acts on the rays of white light 
shining on its particles as to absorb the violet and reflect the com- 
plementary hue, the yellow, which, entering the eye of the observer, 
strikes his retina, and thus conveys to the brain the impression of 
yellowness 5 and the red modification, though actually the same 



198 THE METALLIC RADICALS. 

chemical substance, is sufficiently different in the structure of its 
crystals to absorb the green constituent of white light and reflect 
the complementary ray, the red. 

Illustration of the Chemical Law of Multiple Proportions (p. 49). — 
Applying the atomic theory to the above iodides, it will at once be. 
apparent why mercury and iodine should combine in the proportion 
of 200 of mercury with either 127 or 254 of iodine, and not with 
any intermediate quantity. For it is part of that theory that 
masses are composed of atoms, and that atoms are indivisible, and 
that the weight of the atom of mercury is to that of iodine as 200 is 
to 127. Mercury and iodine can only combine, therefore, in atomic 
proportions, atom to atom (which is the same as 200 to 127), or one 
atom to two atoms (which is the same as 200 to 254). To attempt to 
combine them in any intermediate proportion would be useless ; a 
mere mixture of the two iodides would result. A higher proportion 
of mercury than 200 to 127 of iodine gives but a mixture of mer- 
curous iodide and mercury ; a higher proportion of iodine than 
254 to 200 of mercury gives but a mixture of mercuric iodide and 
iodine. Or, for example, 200 grains of mercury mixed with, say, 
200 of iodine would yield 139 grains of mercurous iodide and 261 
of mercuric iodide ; for the 200 grains of mercury uniting with 127 
of the iodine give, for the moment, 327 grains of mercurous iodide 
and 73 of iodine still free. The 73 grains of iodine will immedi- 
ately unite with 188 of the mercurous iodide (for if 127 of I require 
327 of Hgl to form Hgl 2 , 73 will require 188) and form 261 grains 
of mercuric iodide, diminishing the 327 grains of mercurous iodide 
to 139. 

Note on Atomic Weight. — But the student will ask, Does 127 repre- 
sent the atomic position of iodine, relative, of course, to 1 of hydro- 
gen, 16 of oxygen, and so on ? Yes ; because all synthetical and 
analytical operations with iodine show that 127 parts by weight is 
the quantity in which iodine migrates from compound to compound, 
or either displaces or is displaced by chlorine or bromine ; secondly, 
because equal gaseous volumes of such elements contain equal 
numbers of atoms, and such equal volumes weighing 1, 16, 127, etc., 
each of the atoms of the respective elements must weigh 1, 16, 127, 
etc. ; and thirdly, because similar numerical relationships are met 
with when the specific heats of the elements are determined or 
when their electrical, optical, isomorphic, and other relationships are 
studied. {Vide Index under the words " Atomic," " Constitution," 
"Molecular," " Structure," etc.). 

Preparation of Red Mercury Iodide by Precipitation. — To a 
few drops of a solution of a mercuric salt (corrosive sublimate, 
for example) add solution of potassium iodide, drop by drop ; 
a precipitate of mercuric iodide forms, and at first redissolves, 
but is permanent when sufficient iodide has been added. Con- 
tinue the addition of potassium iodide ; the precipitate is 
redissolved. 

HgCl, + 2KI == Hgl, + 2KC1 

Mercuric chloride. Potassium iodide. Mercuric iodide. Potassium chloride. 



MERCURY. 199 

Notes. — When first precipitated mercuric iodide is yellowish-red, 
but soon changes to scarlet. Its solubility either in solution of the 
mercuric salt or in solution of potassium iodide renders the detection 
of a small quantity of a mercuric salt by potassium iodide, or a 
small quantity of an iodide by a mercuric solution, difficult, and 
hence lessens the value of the reaction as a test. But the reaction 
has synthetical interest, the method of precipitation being that 
adopted in the British and United States Pharmacopoeias (Hydrar- 
gyri Iodidi Riibrum, U. S. P., or Red Mercuric Iodide). Mercuric 
iodide thus made has the same composition as that prepared by 
direct combination of its elements. Equivalent proportions of the 
two salts must be used in making the preparation (HgCl 2 = 271 ; 
2KI = 332). About 4 parts of corrosive sublimate are dissolved in 
50 or 60 of water (warmth quickens solution) and 5 of potassium 
iodide in 15 or 20 of water, the solutions mixed and the precipitate 
collected on a filter, strained, washed twice with distilled water, and 
dried on a plate over a water-bath. Mercuric nitrate, which is more 
soluble, and therefore somewhat more convenient for use on the 
large scale, may be used instead of the mercuric chloride. The 
mercury in mercuric or mercurous iodide is set free, and sublimes in 
globules on heating either powder with dried sodium carbonate in a 
test-tube ; the iodine may be detected by digesting with solution of 
soda, filtering, and to the solution of sodium iodide thus formed 
adding starch-paste and acidulating with nitrous acid, when blue 
iodide of starch results. Mercuric iodide is insoluble in water, 
slightly soluble in alcohol, tolerably soluble in ether. Precipitated 
red mercury iodide mixed with white wax, lard, and oil forms the 
Utiguentum Hydrargyri Iodidi Rubri, B. P. 

" Mercuric Potassium Iodide Test-solution," U. S. P., is made by 
dissolving in a little water 13.5 grms. of mercuric iodide, and mixing 
with a solution of 49.8 grms. of potassium iodide, and, after well 
shaking, making up to 1000 cc. 

The Two Nitrates. 

Second Synthetical Reaction. — Place a globule of mercury 
about half the size of a pea in a test-tube ; add 20 or 30 drops 
of nitric acid ; boil slowly until red fumes no longer form ; set 
aside. On cooling, if a globule of mercury still remains in the 
tube, crystals of mercurous nitrate separate. These may be 
dissolved in water slightly acidulated by nitric acid. The 
solution may be retained for subsequent analytical operations. 
3Hg + 4HN0 3 = 3HgN0 3 + 2H 2 + NO. 

Third Synthetical Reaction. — Place mercury in excess of strong 
nitric acid and warm the mixture ; mercuric nitrate is formed, 
and will be deposited in crystals as the solution cools ; or to 
crystals of mercurous nitrate add nitric acid, and boil until red 
fumes cease to form. Retain the product for a subsequent 
experiment. 



200 THE METALLIC RADICALS. 

When mercury and nitric acid are boiled together, mercurous 
nitrate is formed if the mercury he in excess, while mercuric 
nitrate is produced if the acid preponderate. 

The mercuric nitrates vary somewhat in composition, according to 
the proportion, strength, and temperature of the acid used in their 
formation. A mercuric nitrate may be obtained having the formula 
Hg2x\0 3 . 

3Hg + 8HN0 3 = 3(Hg2N0 3 ) + 2NO + 4H 2 

Mercury. Nitric acid. Mercuric nitrate. Nitric oxide. Water. 

Mercuric Oxynitrates. — From the normal mercuric nitrate several 
oxy nitrates may be obtained. Thus on merely evaporating a solu- 
tion of mercuric nitrate and cooling, crystals having the formula 
Hg 6 3 GN0 3 are deposited. The latter, by washing with cold water, 
yield a yellow pulverulent oxynitrate, Hg 6 4 4N0 3 : mixed with lard, 
this has sometimes been used as an ointment. Boiled in water, the 
yellow gives a brick-red oxynitrate, Hg 6 5 2N0 3 . 

The pharmacopoeial preparations of mercuric nitrate are Solution 
of Mercuric Nitrate, Liquor Hydrargyri Nitratis, U. S. P., contain- 
ing about 60 per cent, of mercuric nitrate and 11 of free acid, sp. gr. 
2.100, and Unguentum Hydrargyri Nitratis, U. S. P. The former is 
made by placing 40 parts of red mercuric oxide in 45 parts of nitric 
acid diluted with 15 parts of water. 

HgO + 2HN0 3 = Hg2N0 3 + H 2 0. 

The unguentum or " citrine ointment" is made by oxidizing lard 
oil with nitric acid, and then adding a solution of mercury in nitric 
acid. It is sometimes diluted with soft paraffin ( Unguentum Hydrar- 
gyri Nitratis Dilutum, B. P.). 

The Two Sulphates. 

Fourth Synthetical Reaction. — Boil 2 or 3 grains of mercury 
with a few drops of strong sulphuric acid in a test-tube, or, 
better, small dish, in a fume-chamber; sulphurous acid gas 
(S0 2 ) is evolved, and mercuric sulphate or mercury 'persulphate 
(Hydrargyri Persulphas, B. P., HgS0 4 ) results — a white, heavy, 
crystalline powder. 

Hg + 2HSO, = HgS0 4 + S0 2 + 2H 2 

Mercury. Sulphuric Mercuric Sulphurous Water, 

acid. sulphate. acid gas. 

Between 2 and 3 ounces of mercuric sulphate may be pre- 
pared from a fluidrachm of mercury and a fluidounce of sul- 
phuric acid, boiled together in a small dish. These equal the 
official proportions. The operation is completed and any excess 
of acid removed by evaporating the mixture of metal and 
liquid to dryness, either in the open air or in a fume-chamber, 
sulphuric acid vapors being excessively irritating to the mucous 
membrane of the nose and throat ; dry crystalline mercuric 



MERCURY. 201 

sulphate remains. If residual particles of mercury are ob- 
served, the mass should be damped with sulphuric acid and 
again heated. 

By-products. — In chemical manufactories secondary products, 
such as the sulphurous gas of the above reaction, are termed by- 
products, and if of value are utilized. In the present case the gas 
is of no immediate use, and is therefore allowed to escape. When 
very pure sulphurous acid gas is required for experiments on the 
small scale, this would be the best method of making it, a delivery- 
tube being adapted by a cork to the mouth of a flask containing 
the acid and metal. The mercury sulphate would then become 
the by-product. 

Mercuric Oxysulphate. — Water decomposes mercuric sulphate into 
a soluble acid salt and an insoluble yellow oxysulphate (Hg 3 2 S0 4 ). 
The latter is called turpeth mineral, from its resemblance in color to 
vegetable turpeth, the powdered root of Ipomcea turpethum, an Indian 
substitute for jalap.. The yellow mercury sulphate was formerly 
official in the British Pharmacopoeia, but now only in the United 
States Pharmacopoeia — Hydrargyri Subsulphas Flavus, or Yellow 
Mercuric Subsulphate. It should be entirely soluble in 10 parts of 
hydrochloric acid. 

Fifth Synthetical Reaction. — Rub a portion of the dry mer- 
curic sulphate of the previous reaction with as much mercury 
as it already contains ; the product, when the two have 
thoroughly blended, is mercurous sulphate (Hg 2 S0 4 ) : it may 
be retained for a subsequent experiment. 

Molecular Weight. — The exact proportion of mercury to sulphate 
is merely a matter of calculation ; for the combining proportion of a 
compound (if it possess any combining power), or its proportion for 
interchange or transposition (metathesis), is the sum of the combin- 
ing proportions, or interchanging or transposing proportions, of its 
constituents. In other words, the molecular weight of a compound is 
the sum of the atomic weights of its elements. In accordance with 
this rule (deduced from the first law of chemical combination, p. 47), 
296 of mercuric sulphate and 200 of mercury (about 3 to 2) are the 
proportions necessary to the formation of mercurous sulphate, Hg 
(200).+ HgS0 4 (296) = Hg 2 S0 4 (496). 

The Two Chlorides. 

Sixth Synthetical Reaction. — Mix thoroughly a few grains 
of dry mercuric sulphate with about four-fifths its weight of 
sodium chloride, and heat the mixture, slowly, in a test-tube in 
a fume-chamber ; mercuric chloride (HgCl 2 ), or corrosive sub- 
limate, mercury bichloride or perchloride (Hydrargyri Per- 
chloridum, B. P.), Hydrargyri Chloridum Corrosivum, U. S. P. 
(Corrosive Mercuric Chloride or Corrosive Chloride of Mercury), 



202 



THE METALLIC RADICALS. 



sublimes and condenses in the upper part of the tube in heavy 
colorless crystals or as a crystalline mass. 

Somewhat larger quantities (in proportion of 20 of sulphate 
to 16 of salt, and, vide infra, 1 of black manganese oxide) may 
be sublimed in a pair of 2-ounce or 3-ounce round-bottomed 
gallipots, the one inverted over the other, and the joint luted 

by moist fireclay (the powdered 
Fig. 36. clay kneaded with water to the 

consistence of dough). The luting 
having been allowed to dry (some- 
what slowly to avoid cracks), the 
pots are placed upright on a sand- 
tray (plate-shape answers very 
well), sand piled round the lower 
and a portion of the upper pot, and 
the whole heated over a good-sized 
gas flame for an hour or more in a 
fume-chamber (see Fig. 36 — pots 
raised to show joint). Red mercury 
iodide and calomel may be sub- 
limed in the same way. The 
Sublimation. former requires 

heat than corrosive sublimate. 




, the latter more, 



HgS0 4 

Mercuric 
sulphate. 



2NaCl == HgCl 2 + Na 2 S0 4 

Sodium Mercuric Sodium 

chloride. chloride. sulphate. 

Note. — If the mercuric sulphate contain any mercurous sulphate, 
some calomel may be formed. This result will be avoided if 2 or 3 
per cent, of black manganese oxide be previously mixed with the 
ingredients, the action of which is to eliminate chlorine from the 
excess of sodium chloride used in the process, the chlorine convert- 
ing any calomel into corrosive sublimate. Sodium manganate and 
a lower manganese oxide are simultaneously produced. 

Precaution. — The operation is directed to be conducted with care 
in a fume-chamber, because the vapor of corrosive sublimate, which 
might possibly escape, is very acrid and highly poisonous. Mer- 
curic chloride volatilizes, though extremely slowly and slightly, at 
warm temperatures. 

10 grains of mercury perchloride and the same quantity of 
ammonium chloride in 1 pint of water form the Liquor Hydrargyri 
Perchloridi, B. P. A dilute aqueous solution of mercury per- 
chloride is liable to decomposition, calomel being precipitated, water 
decomposed, hydrochloric acid formed, and oxygen gas evolved. 
The presence of excess of ammonium chloride, with a portion of 
which the mercuric chloride forms a stable double salt, prevents the 
decomposition. 

Seventh Synthetical Reaction. — Mix a few grains of the mer- 



MERCURY. 203 

curous sulphate of the fifth reaction with about a third of its 
weight of sodium chloride, and sublime in a test-tube ; crystal- 
line mercurous chloride (HgCl) or calomel {Hydrargyri Sub- 
chloridum, B. P., Hydrargyri Chloridum Mite, U. S. P., the 
Mild Chloride of Mercury or Mild Mercurous Chloride) results. 
Larger quantities may be prepared in the manner directed for 
corrosive sublimate, a somewhat higher temperature being 
employed : similar precautions must also be observed. The 
official proportions are 10 of mercuric sulphate to 7 of mercury 
and 5 of dry sodium chloride. " Moisten the mercury sulphate 
with some of the water, and rub it and the mercury together 
until globules are no longer visible ; add the sodium chloride, 
and thoroughly mix the whole by continued trituration. When 
dry, sublime by a suitable apparatus into a chamber of such 
size that the calomel, instead of adhering to its sides as a crys- 
talline crust, shall fall as a fine (dull- white) powder on the floor. 
Wash this powder with boiling distilled water until the wash- 
ings cease to be darkened by a drop of ammonium sulphydrate. 
Finally, dry at a temperature not exceeding 212° F." 



Hg,SO, 


+ 


2NaCl = 


= 2HgCl + 


Na 2 S0 4 


Mercurous 




Sodium 


Mercurous 


Sodium 


sulphate. 




chloride. 


chloride. 


sulphate. 



TJie term calomel (nalbg, kalos, good, and juela^, melas, black) prob- 
ably was simply indicative of the esteem in which black mercury 
sulphide was held, the compound to which the name calomel was 
first applied. 

Test for Corrosive Sublimate in Calomel. — If the mercurous sul- 
phate contain mercuric sulphate, some mercuric chloride will also 
be formed. Corrosive sublimate is soluble in water, calomel 
insoluble ; the presence of the former may therefore be proved by 
boiling a few grains of the calomel in distilled water, filtering and 
testing by sulphuretted hydrogen or ammonium sulphydrate, • as 
described hereafter. If corrosive sublimate be present, the whole 
bulk of the calomel must be washed with hot distilled water till the 
filtrate ceases to give any indications of mercury. Corrosive sub- 
limate is more soluble in alcohol, and still more in ether, calomel 
insoluble. Ether in which calomel has been digested should there- 
fore, after filtration, yield no residue on evaporation. Calomel is 
converted by hydrocyanic acid into mercuric salt and a black powder 
readily yielding metallic mercury. Powell and Bayne have shown 
that a certain proportion of hydrochloric acid arrests this action. 

Note. — 'The above process is that of the British Pharmacopoeia, 
but calomel may also be made by other methods. Calomel mixed 
with lard forms the Unguentum Hydrargyri Subchloridi, B. P., and 
with sulphurated antimony, guaiacum resin, and mucilage of 
tragacanth the Pilidos Antimonii Composites, U. S. P., or " Plum- 
mer's Pills," and with colocynth, jalap, and gamboge the Pilulce 
Catharticce Compositce, U. S. P. 



204 THE METALLIC EADICALS. 

The Two Oxides. 

Eighth Synthetical Reaction. — Evaporate the mercuric nitrate 
of the third reaction to dryness in a small dish, in a fume- 
chamber or in the open air, if more than a few grains have been 
prepared, and heat the residue till no more fumes are evolved ; 
red mercuric oxide (HgO), " red precipitate," the red mercury 
oxide (JEydrargyri Oxidum Rubrum, U. 8. P., or Red Mercuric 
Oxide) remains. 

2(Hg2N0 3 ) = 2HgO + 4N0 2 + 2 

Mercuric nitrate. Mercuric oxide. Nitric peroxide. Oxygen. 

The nitric constituents of the salt may be partially economized by 
previously thoroughly mixing with the dry mercuric nitrate as much 
mercury as is used in its preparation, or as much as it already con- 
tains (ascertained by calculation from the atomic weights and the 
weight of nitrate under operation, as in making mercurous sul- 
phate), and well heating the mixture. In this case the free mercury 
is also converted into mercuric oxide. This is the official process, 
the pharmacopceial quantities being 4 ounces of mercury dissolved in 
4 J fluidounces of nitric acid diluted with 2 ounces of water, the solu- 
tion evaporated to dryness, the residue thoroughly mixed with 4 
more ounces of mercury, and the whole heated until acid vapors 
cease to be evolved. (Mercuric oxide is tested for nitrate by heat- 
ing a little of the sample in a test-tube, when orange nitrous vapors 
are produced, and are visible in the upper part of the tube if nitrate 
be present.) 

Hg2N0 3 -f Hg = 2HgO + 2N0 2 

Mercuric Mercury. Mercuric Nitric 

nitrate. oxide. peroxide. 

Mercuric oxide is an orange-red powder, more or less crystalline 
according to the extent to which it may have been stirred during 
preparation from the nitrate, much rubbing giving it a pulverulent 
character. Mixed with hard and soft paraffin, it yields the Unguen- 
tum Hydrargijri Oxidi Rubri, B. P. (1 part in 8). Mercuric oxide 
in contact with oxidizable organic matter is liable to reduction to 
black or mercurous oxide. 

Ninth Synthetical Reaction. — To a solution of potash or soda 
or lime-water, in a test-tube or larger vessel, add solution of 
corrosive sublimate or of mercuric nitrate ; yellow mercury 
oxide, or yellow mercuric oxide (HgO), is precipitated {Hydrar- 
gyri Oxidum Flavum, U. S. P.). 

HgCl 2 + Ca2HO = HgO + CaCl 2 + H 2 

Mercuric Calcium Mercuric Calcium Water, 

chloride. hydrate. oxide. chloride. 

18 grains of corrosive sublimate to 10 ounces of lime-water form 
the Lotto Hydrargyri Flava, T>. P. The precipitate only differs 
physically from the red mercuric oxide ; the yellow is more 



MERCURY. 205 

minutely divided than the red. Mercuric oxide is very slightly 
soluble in water, but sufficiently so to communicate a metallic taste. 

Tenth Synthetical Reaction. — To calomel add solution of 
potash or soda or lime-water; black mercury oxide, or mer- 
curous oxide (Hg 2 0), is produced, and may be filtered off, 
washed, and dried. (This reaction and the formation of a 
white curdy precipitate on the addition of solution of silver 
nitrate to the filtrate from the mercurous oxide, acidified by 
nitric acid, form sufficient evidence of a powder being or con- 
taining calomel. The curdy precipitate is silver chloride.) 

30 grains of calomel to 10 ounces of lime-water form the Lotio 
Hydrargyri Nigra, B. P. 

2HgCl + Ca2HO = Hg 2 + CaCl 2 + H 2 

Mercurous Calcium Mercurous Calcium Water, 

chloride. hydrate. oxide. chloride. 

Reactions having Analytical Interest (Tests). 
(The mercury occurring as mercuric or mercurous salt.) 

First Analytical Reaction. — The Copper Test. — Deposition of 
mercury upon and sublimation from copper : Place a small 
piece of bright copper, about half an inch long and a quarter 
of an inch broad, in a solution of any salt of mercury, mer- 
curous or mercuric, and heat in a test-tube ; the copper 
becomes coated with mercury in a fine state of division. 
(The absence of any notable quantity of nitric acid must be 
ensured, or the copper itself will be dissolved. See below.) 
Pour away the supernatant liquid from the copper, wash the 
latter once or twice by pouring water into, and then out of, 
the tube, remove the metal, take off excess of water by gentle 
pressure in a piece of filter-paper, dry the copper by passing it 
quickly through a flame, holding it by the fingers ; finally, place 
the copper in a dry, narrow test-tube, and heat to redness in a 
flame, the tube being held almost horizontally ; the mercury 
sublimes and condenses as a whitish sublimate of minute glob- 
ules on the cool part of the tube outside the flame. The 
globules aggregate on gently pressing with a glass rod, and 
are especially visible where flattened between the rod and the 
side of the test-tube. 

Notes on the Test. — This is a valuable test for several reasons : 
It is very delicate when performed with care ; it brings before the 
observer the element itself — one which from its metallic lustre and 
fluidity cannot be mistaken for any other ; it is a test for mercurous 
and mercuric salts ; it eliminates mercury in the presence of most 
other substances, organic or inorganic. 
10 



206 THE METALLIC RADICALS. 

In performing the test the presence of any quantity of nitric 
acid may be avoided by adding an alkali until a slight permanent 
precipitate appears, and then very slightly reacidifying with a drop 
or two of acetic acid, or by concentrating in an evaporating-dish 
after adding a little sulphuric acid, and then rediluting. 

Tests continued (Mercuric Salts). 

Second Analytical Reaction. — To a few drops of a solution 
of a mercuric salt (corrosive sublimate, for example) add solu- 
tion of potassium iodide, drop by drop ; a yellowish -red precipitate 
(mercuric iodide, Hgl 2 ) forms, and at first redissolves, but is 
permanent when sufficient potassium iodide has been added. 
Continue the addition of potassium iodide ; the precipitate is 
redissolved. (See Notes on p. 198.) 

Third Analytical Reaction. — Add a solution of mercuric salt 
to solution of ammonia, taking care that the mixture, after 
well stirring, still smells of ammonia ; a white precipitate falls. 

Ammoniated Mercury. 

Performed in a test-tube, this reaction is a very delicate test of 
the presence of a mercuric salt ; performed in larger vessels, the 
mercuric salt being corrosive sublimate (3 ounces dissolved in 3 
pints of distilled water, the solution poured into 4 fluidounces of 
ammonia solution, and the precipitate washed and dried over a 
water-bath), it is the usual and the pharmacopoeial process for the 
preparation of "white precipitate," the old " ammonio-chloride " or 
" amido-chloride of mercury " (so called because then considered to 
be a compound of mercury with chlorine and with amidogen, NH 2 , 
or HgCl 2 Hg2NH 2 , chloride and amide of mercury), now known as 
ammoniated mercury {Hydrargyrum Ammoniatu?n, U. S. P.). 

Constitution of Ammoniated Mercury. — This precipitate is now, 
however, considered to be mercuric-ammonium chloride (NH 2 Hg / Cl) ; 
that is, ammonium chloride (NH 4 C1) in one molecule of which two 
univalent atoms of hydrogen are substituted by one bivalent atom 
of mercury. 

HgCl 2 + 2NH 4 HO = NH 2 Hg"Cl + NH 4 C1 + 2H 2 

Mercuric Ammonia. " White Ammonium Water, 

chloride. precipitate." chloride. 

Varieties of Ammoniated Mercury. — If the order of mixing be 
reversed, and ammonia be added to solution of mercuric chloride, 
a double mercuric-ammonium and mercury chloride results 
(NH 2 HgCl,HgCl 2 ) : it contains 76.55 per cent, of mercury. Pre- 
viously to the year 1826 "white precipitate" was officially made 
by adding a fixed alkali to a solution of equal parts of corrosive 
sublimate and sal-ammoniac ; this gave a double mercuric-ammo- 
nium and ammonium chloride (NH 2 HgCl,NH 4 Cl), containing 65.57 
per cent, of mercury. This compound is now known as "fusible 
white precipitate," because at a temperature somewhat below red- 



MERCURY. 



207 



ness it fuses and then volatilizes. The " white precipitate,' ' which 
has been official since 1826, contains, theoretically, 79.52 per cent, 
of mercury. The true compound may be distinguished as " infusible 
white precipitate," from the fact that when heated it volatilizes 
without fusing. An ointment of this body is official (Unguentum 
Hydrargyri Ammoniati, U. S. P.). Prolonged washing with water 
converts " white precipitate " into a yellowish compound (NH 2 HgCl,- 
HgO) ; hence the official preparation is not thoroughly freed from 
the ammonium chloride which is formed during its manufacture, 
but which, if present in larger proportion than 7 or 8 per cent., 
gives to it the character of partial or complete fusibility. The 
officially recognized " ammoniated mercury " should volatilize at a 
temperature below redness without fusing, and should yield 77.5 
per cent, of metallic mercury. With iodine, chlorine, or bromine 
white precipitate may yield the highly and dangerously explosive 
nitrogen iodide, chloride, or bromide. 

Note. — Mercuric-ammonium chloride is only one member of a 
large class of compounds derivable from the various salts of ammo- 
nium by substitution of atoms of hydrogen in the molecules by 
atoms of other radicals. The composition of mercurous-ammonium 
chloride (see page 208) and of silver ammonio-nitrate (B. P.) is con- 
sistent with this view. In these formulas ammonium is symbolized 
by NH 4 or Am indifferently. The use of the latter promotes clear- 
ness in the formulas, but it must only be employed when the ammo- 
nium acts like an elementary radical. 



N 




01 




ammonium 
chloride. 



(h< 



Mercuric 

ammonium 

chloride. 



N 



NO, 



Am 
H 
lH ) 

Argent-ammon- 
ammonium nitrate. 



The composition of the copper ammonio-sulphates (pp. 177 and 
193) is consistent with the second and third of the following formulas, 
the first being that of ammonium sulphate : 



N, 



S0 4 





The iodide of dimercuric-ammonium (NHg'^I) is formed in testing 
for ammonia by the " Nessler " reagent. ( Vide Index.) Troost has 



Fourth Analytical Reaction. — Pass sulphuretted hydrogen 
through a mercuric solution ; a black precipitate (mercuric 
sulphide, HgS) falls. 

Note 1.— Sulphuretted hydrogen also precipitates mercurous sul- 
phide (Hg 2 S) from mercurous solutions, and in appearance the pre- 
cipitates are alike ; hence this reagent does not distinguish between 



208 THE METALLIC RADICALS. 

mercurous and mercuric salts. But in the course of systematic 
analysis mercuric salts are thrown down from solution as sulphide 
after mercurous salts have been otherwise removed. Both sulphides 
are insoluble in ammonium sulphydrate. 

Note 2. — An insufficiency of gas gives a white or colored precipitate 
of oxy sulphide. Prolonged contact with sulphuretted hydrogen or 
a sulphydrate, especially if warm, converts the black into a red 
sulphide. 

Ethiops mineral, the old Hydrargyri Sulphuretum cum Sulphure, 
is a mixture of mercury sulphide and sulphur, obtained on trit- 
urating the elements in a mortar till globules are no longer visible. 
Its name is probably in allusion to its similarity in color to the skin 
of the iEthiop. It was formerly official. 

Vermilion is mercuric sulphide prepared by sublimation. For a 
description of the Chinese method of manufacturing it, see the 
Pharmaceutical Journal for December 17, 1881. 

Tests continued (Mercurous Salts). 

Fifth Analytical Reaction. — To a solution of a mercurous 
salt (the mercurous nitrate obtained in the second synthetical 
reaction, for example) add hydrochloric acid or any soluble 
chloride ; a white precipitate (calomel, HgCl) occurs. This 
reaction was formerly official in the Dublin Pharmacopoeia as a 
process for the preparation of calomel. 

Sixth Analytical Reaction. — To solution of a mercurous salt 
add potassium iodide ; a green precipitate results (mercurous 
iodide, Hgl). 

Seventh Analytical Reaction. — To a mercurous salt, dissolved 
or undissolved (e.g. calomel), add ammonia; a black salt (e.g. 
mercurous-ammonium chloride (NH 2 Hg 2 Cl) is formed. (See 
page 206 for explanation of composition.) 

Other Tests for Mercury. 

The elimination of mercury in the actual state of metal by 
the copper test, coupled with the production or non-production 
of a white precipitate on the addition of hydrochloric acid to 
the original solution, is usually sufficient evidence of the pres- 
ence of mercury and its existence as a mercurous or mercuric 
salt. But other tests may sometimes be applied with advantage. 
Thus metallic mercury is deposited on placing a drop of the 
solution on a plate of gold (sovereign or half-sovereign) and 
touching the drop and the edge of the plate simultaneously 
with a key : an electric current passes under these circum- 
stances from the gold to the key, and thence through the liquid 
to the gold, decomposing the salt, the mercury of which forms 
a white metallic spot on the gold, while the other elements go 



MEECURY. 209 

to the iron. This is called the galvanic test, and is useful for 
clinical purposes. Solution of stannous chloride (SnCl 2 ) (see 
Index) from the readiness with which it forms stannic salts 
(SnCl 4 , Sn0 2 , etc.) gives a white precipitate of mercurous chlo- 
ride in mercuric solutions, and quickly still further reduces this 
mercurous chloride (and other mercury salts) to a grayish mass 
of finely-divided mercury ; this is the old magpie test, probably 
so called from the white and gray appearance of the precipitate. 
The reaction may even be obtained from such insoluble mercury 

compounds as " white precipitate." Confirmatory tests for 

mercuric and mercurous salts will be found in the action of 
solution of potash, solution of soda, lime-water, solution of 
ammonia, and solution of potassium iodide. ( Vide pages 205, 
206, and 208.) Normal alkaline carbonates produce yellow- 
ish mercurous carbonate and brownish-red mercuric carbonate, 

both of them unstable. Alkaline bicarbonates give yellowish 

mercurous carbonate with mercurous solutions, and with mer- 
curic salts white (becoming red) mercuric oxysalt. Yellow 

potasssium chromate (K 2 O0 4 ) gives with mercurous salts a 

red precipitate (mercurous chromate, Hg 2 Cr0 4 ). Mercury 

and all its compounds are volatile, many of them being decom- 
posed at the same time, and yielding globules of condensed 
metal; the experiment is most conveniently performed in a 

test-tube. All dry compounds of mercury are decomposed 

when heated in a dry test-tube with dried sodium carbonate, 
mercury subliming and condensing in visible globules, or as a 
whitish deposit yielding globules when rubbed with a glass rod. 
Antidote. — Albumen gives a white precipitate with solution 
of mercuric salts ; hence the importance of administering 
white of egg, while waiting for a stomach-pump or stomach- 
siphon, in case of poisoning by corrosive sublimate. 



QUESTIONS AND EXERCISES. 

Name the chief ore of mercury, and describe a process for the extrac- 
tion of the metal. — Give the properties of mercury. — In what state does 
mercury exist in "gray powder" ? — What other preparations of metallic 
mercury itself are employed in medicine? — State the relation of the 
mercurous to the mercuric compounds. — Distinguish between an alloy 
and an amalgam. — State the formulae of the two mercury iodides. — Under 
what circumstances has mercuric iodide different colors? — Illustrate the 
chemical law of multiple proportions as explained by the atomic theory, 
employing for that purpose the stated composition of the two mercury 
iodides. — Write down the formulae of mercurous and mercuric nitrates 
and sulphates. — How is mercuric sulphate prepared ? — What is the formula 
of " turpeth mineral " ? — Describe the processes necessary for the conver- 
sion of mercury into calomel and corrosive sublimate, using diagrams. — 
Why is black manganese oxide sometimes mixed with the other ingre- 



210 THE METALLIC RADICALS. 

dients in the preparation of corrosive sublimate ? — Give the chemical and 
physical points of difference between calomel and corrosive sublimate. — 
How may calomel in corrosive sublimate be detected ? — Work out a sum 
showing how much mercury will be required in the manufacture of 1 
ton of calomel. Ans. 17 cwt. nearly. — Mention the official preparations 
of the mercury chlorides. — Give the formulae and mode of formation of 
the red, yellow, and black mercury oxides, employing diagrams. — Explain" 
•the action of the chief general test for mercury. — How are mercurous 
and mercuric salts analytically distinguished? — Give a probable view of 
the constitution of Hydrargyrum Ammoniatum, and an equation showing 
how it is made. — State the best temporary antidote to poisoning by 
mercury. 



LEAD. 

Symbol, Pb. Atomic weight, 206.4. 

Source. — The ores of lead are numerous, but the one from which 
the metal is chiefly obtained is lead sulphide (PbS), or galena (from 
yalrjvrj, galene, tranquillity, perhaps from its supposed effect in 
allaying pain). 

Preparation. — The ore is- first roasted in a current of air ; much 
sulphur is thus burnt off as sulphurous acid gas, while some of the 
metal is converted into oxide and a portion of the sulphide oxidized 
to sulphate. Oxidation being stopped when the mass presents certain 
appearances, the temperature is raised, and the oxide and sulphate, 
reacting on undecomposed sulphide, yield the metal and much sul- 
phurous acid gas: 2PbO+ PbS = Pb 3 + S0 2 and PbS0 4 -f PbS = 
Pb 2 + 2S0 2 . 

Uses. — The uses of lead are well known. Alloyed with some 
arsenum, it forms common shot; with antimony gives type-metal; 
with tin, solder ; and in smaller quantities enters into the compo- 
sition of Britannia metal, pewter, and other alloys. Lead is so 
slightly attacked by acids that chemical vessels and instruments are 
sometimes made of it. Hot hydrochloric acid slowly converts it 
into lead chloride, with evolution of hydrogen. Sulphuric acid by 
aid of air only very slightly attacks it, with formation of lead sul- 
phate and water. Even nitric acid very slowly converts it into 
nitrate, with evolution of nitric oxide and nitrous oxide gases and 
water. 

The salts of lead used in pharmacy and all other preparations of 
lead are obtained, directly or indirectly, from the metal itself. 
Heated in a current of air, lead combines with oxygen and forms 
lead oxide (PbO), a yellow powder (massicot), or, if fused and solid- 
ified, a brighter, reddish-yellow, heavy mass of bright scales (Plumbi 
Oxidum, or Lead Oxide, U. S. P.), termed litharge (from Mdog, lithos, 
a stone, and apyvpoq, arguros, silver). It is from this oxide that the 
chief lead compounds are obtained. Lead oxide, by further roasting 
in a current of air, yields red lead (or minium), Pb 3 4 or Pb0 2 2PbO. 
Both oxides are much used by painters, paper-stainers, and glass- 
manufacturers. White lead is a mixture of lead carbonate (PbC0 3 ) 
and hydrate (Pb2HO) (commonly 2 molecules of the former to 1 of 
the latter), usually ground up with about 7 per cent, of linseed oil ; 



LEAD. 211 

it is made by exposing lead, cast in spirals or little gratings, to the 
action of air, acetic fumes, and carbonic acid gas, the latter gen- 
erated from decaying vegetable matter, such as spent tan : lead 
oxyacetate slowly but continuously forms, and is as continuously 
decomposed by the carbonic acid gas, with production of hydrate 
and carbonate, or dry ivhite lead. The grating-like masses, when 
ground, form the heavy white pulverulent official Plumbi Carbonas, 
U. S. P. The latter is the active constituent of Unguentum Plumbi 
Carbonatis, U. S P., the old Unguentum Cerussce. It is also made 
by bringing carbonic acid gas and litharge together in a solution of 
lead acetate. 

Lead compounds are poisonous, producing saturnine colic, and 
even paralysis. These effects are termed saturnine from an old 
name of lead, satum. The alchemists called lead saturn, first, 
because they thought it the oldest of the seven then known metals, 
and it might therefore be compared to Saturn, who was supposed to 
be the father of the gods : and, secondly, because its power of dissolv- 
ing other metals recalled a peculiarity of Saturn, who was said to 
be in the habit of devouring his own children. 

Quantivalence. — The atom of lead is sometimes quadrivalent 
(Pb /7// ), but in most of the compounds used in medicine it exerts 
bivalent activity only (Pb 7/ ). 

Reactions having Synthetical Interest. 

Lead Acetate, or Acetate of Lead. 

First Synthetical Reaction. — Place a few grains of lead oxide 
in a test-tube, add about an equal weight of water and two 
and a half times its weight of acetic acid, and boil ; the oxide 
dissolves (or, rather, disappears — dissolves with simultaneous 
decomposition) and forms a solution of lead acetate (Pb2C 2 - 
H 3 2 ). When cold or on evaporation, if much water has been 
used (the solution being kept faintly acid), crystals of lead 
acetates (Pb2C 2 H 3 2 ,3H 2 0), Plumbi Acetas, U. S. P., are 
deposited. Larger quantities are obtained by the same method. 

PbO + 2HC 2 H 3 2 = Pb2C 2 H 3 2 + H 2 

Lead oxide. Acetic acid. Lead acetate. Water. 

The salt is termed Sugar of Lead, from its sweet taste. Besides 
its direct use in pharmacy, it forms three-fourths of the Pilula 
Plumbi cum Opio, B. P., is the chief constituent of Unguentum 
Plumbi Acetatis, B. P., and an ingredient in Suppositoria Plumbi 
Composita, B. P. 

Lead Subacetate or Oxyacetate. 

Second Synthetical Reaction. — Boil lead acetate with four 
times its weight of water and rather more than two-thirds its 
weight of lead oxide ; the filtered liquor is solution of lead 



212 



THE METALLIC RADICALS. 



oxyacetate, Liquor Plumbi Subacetatis, U. S. P., solution of 
subacetate of lead. 

The official liquor is made by boiling 170 parts of acetate and 100 
of oxide in 800 of distilled water for half an hour (constantly stir- 
ring), filtering, and making up for any loss during evaporation by 
diluting the nitrate with boiled and cooled distilled water until it 
weighs 1000 parts. Sp. gr. about 1.195. 

A similar solution was used by M. Goulard, who called it Extrac- 
tum Satumi, and drew attention to it in 1770. It is now frequently 
termed Goulard's Extract. A more dilute solution, 3 of liquor and 
97 of boiled and cooled distilled water, is also official in the Phar- 
macopoeia under the name of Diluted Solution of Lead Subacetate 
{Liquor Plumbi Subacetatis Dilutus). The latter is commonly 
known as Goulard Water or " lead-water." The stronger solution 
is the chief ingredient in Ceratum Plumbi Subacetatis, U. S. P., 
cerate of lead subacetate, a slight modification of the old Goulard's 
cerate. A strong solution of oxyacetate of lead in glycerin con- 
stitutes the Glycerinum Plumbi Subacetatis, B. P., and this with a 
mixture of soft and hard paraffin gives the Unguentum Glycerini 
Plumbi Subacetatis, B. P., a modification of the old Goulard's cerate. 

Lead Oxyacetates. — The official "subacetate of lead" is not a 
definite chemical salt. It is probably a mixture of two lead sub- 
acetates, which are well-known crystalline compounds, and which 
the author is disposed to regard as having a constitution similar to 
that he has already indicated for some other salts. (See Iron and 
Antimony, also Bismuth.) Exposed to air, it absorbs carbonic acid 
gas, and lead hydrato-carbonate is deposited. 

Lead acetate (3 molecules) . . . Pb 3 6C 2 H 3 2 

n « p f Lead pyro-oxyacetate Pb 3 04C 2 H 3 2 

' { Goulard's oxyacetate Pb 3 2 2C 2 H 3 2 



Lead oxide (3 molecules) . . 



PbO + 

Lead oxide. 



Pb2C 2 H 3 2 

Lead acetate. 



Pb 2 02C 2 H 3 2 , 

Official " subacetate. 



or 3PbO + 3(Pb2C 2 H 3 2 

Lead oxide. Lead acetate. 



Pb 3 04C 2 H 3 2 



+ 



Pb 3 2 2C 2 H 3 2 



Pyro-oxvacetate. Goulard's oxyacetate. 
'The official " subacetate." 



Lead Nitrate, Red Lead, Lead Peroxide. 

Third Synthetical Reaction, — Digest a few grains of red lead 
in nitric acid and water ; lead nitrate (Pb2N0 3 ) is formed, and 
remains in solution, while a puce-colored lead peroxide (Pb0 2 ) 
is precipitated. Lead Nitrate (Plumbi Nitr as, U. S. P.) is more 
directly made by dissolving litharge (PbO) in nitric acid. 

PbO + 2HN0 3 = Pb2N0 3 + H 2 0. 

The former reaction serves to bring before the student two other 
lead oxides — namely, red lead (Pb 3 4 ) and lead peroxide (Pb0 2 ). In 
the latter oxide the quadrivalent character of lead is obvious. 



LEAD. 213 

Lead nitrate is used officially in preparing lead iodide. For the 
latter purpose the above mixture may be filtered, the precipitate of 
lead peroxide purified from adhering nitrate by passing hot water 
through the filter, the filtrate and washings evaporated to dryness to 
remove excess of nitric acid, the residual lead nitrate redissolved by 
ebullition with a small quantity of hot water, and the solution set 
aside to crystallize or a portion at once used for the following exper- 
iment. Lead nitrate forms white crystals derived from octahedra. 

Lead peroxide dissolved in cold strong hydrochloric acid appar- 
ently yields an unstable perchloride (PbClJ. 

Lead Iodide, or Iodide of Lead. 

Fourth Synthetical Reaction. — To a neutral solution of lead 
nitrate add solution of potassium iodide ; a precipitate of lead 
iodide (Pbl 2 ) falls (Plumbi Iodidum, U. S. P.). Equal weights 
of the salts may be used in making large quantities. 

Pb2N0 3 + 2KI = Pbl 2 + 2KN0 3 

Lead nitrate. Potassium iodide. Lead iodide. Potassium nitrate. 

Lead iodide is the chief ingredient in Emplastrum Plumbi Iodidi, 
B. P., and Unguentum Plumbi Iodidi, B. P. Lead iodide is soluble 
in solution of ammonium chloride. 

Crystals of Lead Iodide. — Heat lead iodide with the super- 
natant liquid, and, if necessary, filter ; the salt is dissolved, 
and again separates in golden crystalline scales as the solution 
cools. 

Lead Oleate (Lead Plaster). 

Fifth Synthetical Reaction. — Boil together in a small dish 
a few grains of very finely powdered lead oxide, with twice its 
weight of olive oil and two or three times as much water, well 
stirring the mixture, and from time to time replacing water 
that has evaporated ; the product is a white mass of lead oleate 
(Pb2C 18 H 3 30 2 ) (Emplastrum Plumbi, B. P.), glycerin remain- 
ing in solution. Larger quantities are prepared in the same 
manner. 

3PbO + 3H 2 + 2(C 3 H 5 3C 18 H 33 2 ) 

Lead oxide. Water. Glyceryl oleate (olive oil or oleine). 

= 3(Pb2C 18 H 33 2 ) + 2C 3 H 5 3HO) 

Lead oleate (lead plaster). Glyceryl hydrate (glycerin). 

The action between the lead oxide and olive oil is slow, requiring 
several hours for its completion. Lead plaster is a constituent of 
seven of the thirteen plasters [Emplastrum) mentioned in the United 
States Pharmacopoeia. 

The glycerin may be obtained by treating the aqueous product 
of the above reaction with sulphuretted hydrogen to remove a trace 
of lead, then digesting with animal charcoal, filtering, and evaporat- 
ing. But on the large scale glycerin is produced as a by-product 
10* 



214 THE METALLIC RADICALS. 

in the manufacture of candles, for its elements are found in nearly- 
all vegetable and animal fats. (Vide Index.) If in making lead 
plaster the mixture be evaporated to dryness [Emplastrum Plumbi, 
U. S. P.), some of the glycerin will escape with the steam and some 
remain with the plaster. 

Modes of formation of Lead Chloride, Sulphide, Chromate, Sul- 
phate, Hydrate, and other salts are incidentally described in the 
following analytical paragraphs. 

Reactions having Analytical Interest (Tests). 

First Analytical Reaction. — To solution of a lead salt (ace- 
tate, for example) add hydrochloric acid ; a white precipitate 
(lead chloride, PbCl 2 ) is obtained. Boil the precipitate with 
much water ; it dissolves, but on the solution cooling is rede- 
posited in small acicular crystals, Filter the cold solution, 
and pass sulphuretted hydrogen through it ; a black precipitate 
(lead sulphide, PbS) shows that the lead chloride is soluble to 
a slight extent in cold water. 

Note. — A white precipitate on the addition of hydrochloric acid, 
soluble in hot water and blackened by sulphuretted hydrogen, suffi- 
ciently distinguishes lead salts from those of other metals 5 but the 
non-production of such a precipitate does not prove the absence of a 
small quantity of lead, lead chloride being slightly soluble in cold 
water. 

Second Analytical Reaction. — Through a dilute solution of 
a lead salt acidulated with hydrochloric acid pass sulphuretted 
hydrogen ; a black precipitate (lead sulphide, PbS) occurs. 

Lead in Water. — The foregoing is a very delicate test. Should a 
trace of lead be present in water used for drinking purposes, sul- 
phuretted hydrogen will detect it. On passing the gas through a 
pint of such (acidulated) water a brownish color is produced. If 
the tint is scarcely perceptible, set the liquid aside for a day ; the 
gas will become decomposed, and a thin layer of sulphur be found 
at the bottom of the vessel — white if no lead be present, but more or 
less brown if it contain lead sulphide. Hygienists regard one- 
twentieth grain of lead per gallon as dangerous, while a lesser 
quantity may do harm. Water commonly used for drinking pur- 
poses should not contain a trace. 

Third Analytical Reaction. — To solution of a lead salt add 
ammonium sulphydrate ; a black precipitate (lead sulphide) 
falls, insoluble in excess. 

Fourth Analytical Reaction.— To solution of a lead salt add 
solution of potassium chromate (K 2 Cr0 4 ) ; a yellow precipitate 
(lead chromate, PbCr0 4 ) is formed, insoluble in weak acids or 
in solution of ammonium chloride. 



LEAD. 215 

Chromes. — This reaction has technical as well as analytical inter- 
est. The precipitate is the common pigment termed chrome yellow 
or lemon chrome. Boiled with lime and water, a portion of the 
chromic radical is removed as a soluble calcium chromate, and a 
lead oxychromate, of a bright red or orange color {orange chrome), 
is produced. 

Fifth Analytical Reaction. — To solution of a lead salt add 
dilute sulphuric acid or solution of a sulphate ; a white precipi- 
tate (lead sulphate, PbSO*) falls. 

Lead sulphate is slightly soluble in strong acids and in solutions 
of alkaline salts ; it is insoluble in acetic acid. It is readily dis- 
solved, and, indeed, decomposed, by solution of ammonium acetate, 
the liquid yielding the ordinary reactions with soluble chromates 
and iodides. 

In dilute solutions the above sulphuric reaction does not take 
place immediately ; the precipitate, however, falls after a time : its 
appearance may be hastened by evaporating the mixture nearly to 
dryness and then rediluting. 

The white precipitate generally noticed in the vessels in which 
diluted sulphuric acid is kept is lead sulphate, derived from the 
leaden chambers in which the acid is made : solubility in strong acid 
and insolubility in weak explains its appearance. 

Antidotes. — From the insolubility of lead sulphate in water, the 
best antidote in a case of poisoning by the acetate or other soluble 
lead salt is a soluble sulphate, such as Epsom salt, sodium sulphate 
or alum, vomiting being also induced or the stomach-pump or 
stomach-siphon applied as quickly as possible. 

Other tests for lead will be found in the reaction with potas- 
sium iodide (vide p. 213) ; with alkaline carbonates, a white pre- 
cipitate (2PbC0 3 + Pb2HO) insoluble in excess ; with alkalies, 
a white precipitate (Pb2HO) more or less soluble in excess ; 
with alkaline phosphates, arsenates, ferrocyanides, and cyanides, 
precipitates mostly insoluble, but of no special analytical interest. 
Insoluble salts of lead may be decomposed by solution of 
potash (KHO) or soda (NaHO). 

The metal is precipitated in a beautifully crystalline state by 
metallic zinc and some other metals ; the lead tree is thus 
formed. The blowpipe flame decomposes solid lead com- 
pounds placed in a small cavity in a piece of charcoal, a soft 
malleable bead of metal being produced and a yellowish ring 
of oxide deposited on the charcoal. 



QUESTIONS AND EXEECISES. 

Write down questions descriptive of the smelting of galena. — Mention 
some of the alloys of lead. — How is litharge produced ?— Give the formulae 
of white lead and red lead.— Describe the manufacture of white lead.— 



216 THE METALLIC RADICALS. 

What is the quantivalence of lead ? — Draw a diagram showing the forma- 
tion of lead acetate. — Describe the preparation and composition of 
Liquor Plumbi Subacetatis. — What is the action of nitric acid on red lead, 
litharge, and lead ?— How is the official lead iodide prepared ? — Describe 
the reaction between lead oxide, water, and olive oil at the temperature 
of boiling water, and give chemical formulae explanatory of the constitu- 
tion of the products. — Mention the chief tests for lead. — How would you 
search for lead in potable water ? — What is the composition of chrome 
yellow? — State a method whereby lead, barium, and silver, in solution, 
may be separated from each other. — Name the best antidote in cases of 
poisoning by lead salts. 



SILVER. 

Symbol, Ag. Atomic weight, 108. 

Source. — This element occurs in nature in the metallic state and 
as ore, the common variety of the latter being silver sulphide 
(Ag. 2 S) in combination with much lead sulphide, forming argentif- 
erous galena. 

Preparation. — The lead from such galena (p. 210) is melted and 
slowly cooled ; crystals of lead separate and are raked out from the 
still fluid mass, and thus an alloy very rich in silver is finally 
obtained ; this is roasted in a current of air, whereby the lead is 
oxidized and removed as litharge, pure silver remaining. Other 
ores undergo various preparatory treatments according to their 
nature, and are then shaken with mercury, which amalgamates 
with and dissolves the particles of metallic silver, the mercury being 
subsequently removed from the amalgam by distillation. Soils and 
minerals containing metallic silver are also treated in this way. An 
important improvement in the amalgamation process, by which the 
mercury more readily unites with the silver, consists in the addition 
of a small proportion of sodium to the mercury. — Silver chloride 
may be dissolved from ores by solution of sodium hyposulphite. 

Silver is not readily affected by the weak acid or other fluids of 
food, though it is rapidly tarnished by sulphur or sulphur com- 
pounds. It does not perceptibly attack hydrochloric acid ; reduces 
strong nitric acid to nitrous anhydride (N 2 3 ), and a weaker acid 
to nitric oxide (NO) ; it reduces hot sulphuric acid to sulphurous 
anhydride (S0 2 ), silver sulphate (Ag 2 S0 4 ) being formed. The latter 
salt is crystalline and slightly soluble in water. 

Reactions having Synthetical Interest. 
Impure Silver Nitrate, or Nitrate of Silver. 

First Synthetical Reaction. — Dissolve a silver coin in nitric 
acid ; nitric oxide gas (NO) and nitrous anhydride (N 2 3 ) are 
evolved, and a solution of silver and copper nitrates is obtained. 

Silver Coinage. — Pure silver is too soft for use as coin ; it is there- 
fore hardened by alloying with copper. The silver money of Eng- 
land contains 7.5, of Prussia 25, and of France 10 and 16.5 per 



SILVER. 217 

cent, of copper, for the fineness of the French standard silver is 
0.900 in the five-franc piece, while an inferior alloy of 0.835 is used 
for the lower denominations. The single-franc piece, composed of 
the latter alloy, is still made to weigh 5 grammes, the weight 
originally chosen for the franc as the unit of the monetary scale 
when the fineness of the coin was 0.900. It has now become a 
token, like the British shilling, of which the nominal value exceeds 
the metallic value. 1 pound troy of British standard silver is coined 
into 66 shillings, of which the metal is worth from 50s. to 60s., or 
less or more, according to the market price of silver. The standard 
fineness of this silver is 0.925 — i. e. 3 of copper in 40 of the alloy. 
British silver coins are a legal tender in payments to the amount of 
40s only. 

Silver Chloride, or Chloride of Silver. 

Second Synthetical Reaction. — To the product of the fore- 
going reaction add water and hydrochloric acid or a soluble 
chloride ; white silver chloride (AgCl) is precipitated, copper 
still remaining in solution. Collect the precipitate on a filter 
and wash with water ; it is pure silver chloride. 

Note. — Copper may also be separated by evaporating the solution 
of the metals in nitric acid to dryness and gently heating the resi- 
due, when the copper nitrate is decomposed, but the silver nitrate is 
unaffected. The latter may be dissolved from the residual copper 
oxide by water. 

Silver chloride may be obtained in crystals by evaporation of its 
solution in ammonia. 

Pure Silver. 

Third Synthetical Reaction. — Place the silver chloride of 
the previous reaction in a dish, wet it with dilute sulphuric 
acid, and float a piece of sheet zinc on the mixture ; metallic 
silver is precipitated, and after about one day wholly removed 
from combination. Collect the precipitate on a filter and wash 
with water ; it is pure metallic silver, and is readily fusible 
into a single button, especially if mixed with a little borax 
and nitre. 

Note. — Any considerable quantity of silver chloride may be 
reduced to a lump of the metal by fusion in a crucible, with about 
half its weight of sodium carbonate. The chloride is also reduced 
by boiling with caustic alkali and grape-sugar until a trial sample 
is entirely dissolved by nitric acid. 

Pure Silver Nitrate, or Nitrate of Silver. 

Fourth Synthetical Reaction. — Dissolve the pure silver of 
the previous reaction in nitric acid (3 of silver require about 
2 or 2 h of strong acid diluted with 5 of water), and remove 



218 THE METALLIC RADICALS. 

excess of acid by evaporating the solution to dryness, slightly 
heating the residue ; the product is pure silver nitrate. Dis- 
solve by heating with a small quantity of water ; on the solu- 
tion cooling or on evaporation colorless tabular crystals of 
silver nitrate are obtained. 

3Ag 2 + 8HN0 3 = 2NO + 6AgN0 3 + 4H 2 

Silver. Nitric acid. Nitric oxide. Silver nitrate. Water. 

Notes. — The solution of pure or refined silver (Argentum Purifi- 
cation, B. P.) in nitric acid, evaporation, and crystallization consti- 
tutes the usual process for the preparation of the Silver Nitrate, or 
Nitrate of Silver, Argenti Nitras, U. S. P. The salt fused with 4 per 
cent, of hydrochloric acid (yielding about 5 per cent, of interlacing 
silver chloride), and poured into proper moulds, yields the white 
cylindrical sticks or rods, Moulded Silver Nitrate, or Fused Nitrate 
of Silver, Argenti Nitras Fusus, II. S. P., commonly termed caustic 
(from Kaiu, Tcaio, I burn) or lunar caustic. (The alchemists called 
silver Diana or Luna, from its supposed mysterious connection with 
the moon.) " Caustic points" commonly contain potassium nitrate, 
which imparts toughness, the Diluted Silver Nitrate, or Diluted 
Nitrate of Silver, Argenti Nitras Dilutus, U. S. P., or Mitigated 
Caustic, or Toughened Caustic, containing 1 part of silver nitrate to 
2 parts of potassium nitrate. 

The specimen of silver nitrate obtained in the foregoing reaction, 
dissolved in water, will be found useful as an analytical reagent. 
Silver nitrate is soluble in rectified spirit, but after a time reaction 
and decomposition occur. 

Silver salts are decomposed when in contact with organic matter, 
especially in the presence of light or heat, the metal itself being 
liberated or a black insoluble compound formed. Hence the value 
of the nitrate in the manufacture of indelible ink for marking 
linen ; hence, too, the reason of the practice of rendering silver 
solution clear by subsidence and decantation, rather than by filtra- 
tion through paper ; and hence the cause of those cases of actual 
combustion which have been known to occur in preparing pills con- 
taining silver oxide and essential oil or other organic matter. 
Linen marked with such ink should not be cleansed by aid of 
bleaching liquor, as the marked parts are then apt rapidly to be 
oxidized into perfectly rotten matter, holes resulting. Paul says 
the reaction is as follows : 

Ag 2 + CaCl 2 2 = 2AgCl -f CaO + 2 . 

Silver Oxide, or Oxide of Silver. 

Fifth Synthetical Reaction. — To solution of silver nitrate 
add solution of potash or soda or lime-water ; an olive-brown 
precipitate of silver oxide (Ag 2 0) occurs. The washed and 
dry oxide, like most silver compounds, is decomposed by heat 
with production of metal. It is also reduced by contact with 
(See the previous paragraph.) 



Ca2H0 = 


= Ag 2 


+ 


Ca2N0 3 


+ H 2 0. 


Calcium 


Silver 




Calcium 


Water. 


hydrate. 


oxide. 




nitrate. 





SILVER. 219 

Argenti Oxidum, U. S. P., may be thus made, lime-water being 
the precipitant employed, soda or potash not being so readily 
removed by washing. 3 £ pints of good lime-water will decompose 
£ an ounce of silver nitrate. 

2AgN0 3 + 

Silver 
nitrate. 

Silver oxide is also precipitated on adding ammonia to solution 
of silver nitrate, but it is rapidly taken up by the ammonium nitrate 
formed at the same time, argentammonium nitrate, NH 3 AgN0 3 , 
being, doubtless, produced. More ammonia then yields argentam- 
mon-ammonium nitrate (see p. 207). The direct solution of silver 
oxide in ammonia may give the highly explosive substance known 
as Berthollet's fulminating silver (? NH 2 Ag). Ordinary fulminating 
silver, C 2 N 2 2 Ag 2 , results from the interaction of silver nitrate, 
nitric acid, and alcohol. The mercury compound, C 2 N 2 2 Hg, is 
used in percussion caps. 



Methods of forming several other salts of silver are incidentally 
mentioned in the following analytical paragraphs. 

Reactions having Analytical Interest (Tests). 

First Analytical Reaction. — To a solution of a silver salt add 
hydrochloric acid or other soluble chloride ; a white curdy pre- 
cipitate (silver chloride) falls. Add nitric acid and boil ; the 
precipitate does not dissolve. Pour off the acid and add solu- 
tion of ammonia ; the precipitate dissolves. Neutralize the 
ammoniacal solution by an acid ; the white curdy precipitate 
(silver chloride, AgCl) is reproduced. 

This is the most characteristic test for silver. The precipitated 
chloride is also soluble in solutions of sodium hyposulphite or 
potassium cyanide — facts of considerable importance in photo- 
graphic operations. 

Other analytical reagents than the above are occasionally 

useful. Sulphuretted hydrogen, or ammonium sulphydrate, 

gives a black precipitate (silver sulphide, Ag 2 S), insoluble in 
alkalies. Solutions of potash or soda give a brown precip- 
itate (silver oxide, Ag 2 0), converted into a fulminating com- 
pound by prolonged contact with ammonia. Sodium phos- 
phate gives a pale yellow precipitate (silver phosphate, Ag 3 P0 4 ), 

soluble in nitric acid and in ammonia. Ammonium arsenate 

gives a chocolate-colored precipitate (silver arsenate, Ag 3 As 4 0), 
already noticed in connection with arsenic acid. Potassium 



220 THE METALLIC RADICALS. 

iodide or bromide gives a yellowish-white precipitate, silver 
iodide (Argent i Iodidum, U. S. P., or silver iodide) or bromide 
(Agl or AgBr), insoluble in acids and only slightly soluble in 
ammonia. Potassium cyanide gives a white precipitate (sil- 
ver cyanide, AgCy), soluble in excess, somewhat soluble in 
ammonia, insoluble in dilute nitric acid, soluble in boiling con- 
centrated nitric acid. Argenti Cymiidum, U. S. P., or silver 
cyanide, may be made by distilling a mixture of potassium 
ferrocyanide and dilute sulphuric acid, and passing the result- 
ing hydrocyanic acid into a solution of silver nitrate : HCy + 
AgN0 3 = AgCy + HN0 3 , the precipitate being well washed 

and dried. Yellow potassium chromate (K 2 Cr0 4 ) gives a 

red precipitate (silver chromate, Ag 2 O0 4 ). Red potassium 

chromate also gives a red precipitate (acid silver chromate, 

Ag 2 O0 4 ,O0 3 ). Many organic acids afford insoluble salts 

of silver. Several metals displace silver from solution, mer- 
cury forming in this way a crystalline compound known as the 

silver tree, or arbor Dianse. In the blowpipe flame silver 

salts, placed on charcoal with a little sodium carbonate, yield 
bright globules of metal, accompanied by no incrustation, as 
in the corresponding reaction with lead salts ; the experiment 
may be performed with the nitrate, which first melts, and then, 
like all nitrates, deflagrates, yielding a white metallic coating 
of silver which slowly aggregates to a button. 

Antidotes. — Solution of common salt, sal-ammoniac, or any other 
inert chloride should obviously be administered where large doses of 
silver nitrate have been swallowed. A quantity of sea-water or 
brine would convert the silver into insoluble chloride, and at the 
same time produce vomiting. 



DIRECTIONS FOR APPLYING SOME OF THE FOREGOING REACTIONS 
TO THE ANALYSIS OF AN AQUEOUS SOLUTION OF A SALT OF 
ONE OF THE METALS COPPER, MERCURY (MERCUROUS OR 
MERCURIC), LEAD, SILVER. 

Add hydrochloric acid : 

Silver is indicated by a white curdy precipitate, soluble in 
ammonia. 

Mercurous salts also by a white precipitate, turned black 
by ammonia. 

Lead by a white precipitate, insoluble in ammonia. Con- 
firm by boiling a small portion of the hydrochloric 
precipitate in water ; it dissolves. 



SILVER. 



221 



If hydrochloric acid gives no precipitate, silver and mercu- 
rous salts are absent. Lead can only be present in very small 
quantity. Mercuric salts may be present. Copper may be 
present. Divide the liquid into three portions, and apply a 
direct test for each metal as follows : 

Lead is best detected by the sulphuric test, the tube being 
set aside for a time if the precipitate does not appear 
at once. 
Mercury is best detected by the copper test. If present 

here, it occurs as mercuric salt. 
Copper betrays itself by the blue color of the liquid under 
examination. Confirm by the ammonia test. 
If the above reactions are not thoroughly conclusive, con- 
firmatory evidence should be obtained by the application of 
other reagents for copper, mercury, lead, or silver. 



TABLE OF SHORT DIRECTIONS FOR APPLYING SOME OF THE 
FOREGOING REACTIONS TO THE ANALYSIS OF AN AQUEOUS 
SOLUTION OF SALTS OF ANY OR ALL OF THE METALS 
COPPER, MERCURY (EITHER MERCUROUS OR MERCURIC 
SALT, OR BOTH), LEAD, SILVER. 

Add hydrochloric acid, filter, and wash the precipitate with 
a small quantity of cold water. 



Ppt. 

Pb Hg (ous) Ag. 

Wash with boiling water. 



Ppt. 

Hg (ous) Ag. 

Add NH 4 HO. 



Precipitate 

Hg 

[mercurous), 

black. 



Filtrate 

Ag. 

Add an acid, 

white ppt. 



Filtrate 

Pb. 

Add H,S0 4 , 

white ppt.* 



Filtrate. 

Cu Hg (ic) Pb. 

Divide into three portions. 

Test for 
Cu by NH 4 HO ; blue sol. 
Hg (mercuric) by Cu 5 

globules. 
Pb by H 2 S0 4 ; white ppt * 



* Liquids containing only a small quantity of lead do not readily 
yield lead sulphate on the addition of sulphuric acid. Before lead can 
be said to be absent, therefore, the liquid should be evaporated to dry- 
ness with one drop of sulphuric acid, and the residue digested in water ; 
any lead sulphate then remains as a heavy, white, insoluble powder. 



222 



THE METALLIC RADICALS. 



OUTLINE OF THE FOLLOWING TABLES FOR ANY OR ALL OF 
THE COMMON METALS. 



HC1. 



Hg 

(as mercurous 

salt) 

Pb 

(partially) 

Ag 



H 2 S. 




NHJIS. 


(NH 4 ) 2 C0 3 . 


(NH 4 ) 2 HAs0 4 . 




Cu " 


a 


Zn 


Ba 


Mg 


K 


Hg 

(as mer- 
curic salt) 
Pb* 


f 


Al 
Fe 


Ca 




Na 


(entirely) , 








As 
Sb 


CO 











The practical student should examine solutions containing these 
common metals until he is able to analyze with facility and accu- 
racy. In this way he will best perceive the peculiarities of each 
element and their general relations to each other. As the rarer 
metals are not included here, the tables are not complete analytical 
schemes ; only general memoranda respecting them will, therefore, 
now be given. For complete memoranda, see notes to subsequent 
complete tables. 

MEMORANDA RELATING TO THE GENERAL ANALYTICAL TABLES 
FOR ANY OR ALL OF THE COMMON METALS (p. 224). 

The group-reagents adopted in the table are, obviously, hydrochloric 
acid, sulphuretted hydrogen, ammonium sulphydrate, ammonium car- 
bonate, and ammonium arsenate. If a group-reagent produces no 
precipitate, it is self-evident that there can be no member of the 
group present. At first, therefore, add only a small quantity of a 
group-reagent, and if it produces no effect add no more ; for it is 
not advisable to overload a solution with useless reagents : substances 
expected to come down as precipitates are not infrequently held in 
the liquid by excess of acid, alkali, or strong aqueous solution of 
some group-reagent thoughtlessly added. Indeed, experienced 
manipulators make preliminary trials with group-reagents on a few 
drops only of the liquid under examination :, if a precipitate is pro- 
duced, it is added to the bulk of the original liquid, and the addition 
of the group-reagent continued ; if a precipitate is not produced, the 
few drops are thrown away, and the unnecessary addition of a group- 
reagent thus avoided altogether — an advantage fully making up for 
the extra trouble of making a preliminary trial. While shunning 



See note on p. 221. 



ANALYTICAL CHAKTS. 



223 



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224 



THE METALLIC EADICALS. 



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ANALYTICAL MEMORANDA. 225 

excess, however, care must be taken to avoid deficiency : a substance 
only partially removed from solution through the addition of an in- 
sufficient amount of a reagent will appear where not expected, be 
constantly mistaken for something else, and cause much trouble ; 
this will not occur if the appearance, odor, or reaction of the liquid 
on test-paper be duly observed. It is also a good plan, when a 
group-reagent has produced a precipitate and the latter has been 
filtered out, to add a little more of the reagent to the clear filtrate ; 
if more precipitate is produced, an insufficient amount of the group- 
reagent was introduced in the first instance, but the error is cor- 
rected by simply refiltering ; if no precipitate occurs, the mind is 
satisfied and the way cleared for further operations. 

Group-precipitates, or any precipitates still requiring examination, 
should, as a rule, be well washed before further testing : this is to 
remove the aqueous solution of other substances adhering to the 
precipitate (the mother-liquor, as it is termed), so that subsequent 
reactions may take place fairly between the reagent used and the 
precipitate only. A precipitate is sometimes in so fine a state of 
division as to retard filtration by clogging the pores of the paper, or 
even to pass through the filter altogether 5 in these cases the mixture 
may be warmed or boiled (or a fresh quantity of the original solu- 
tion may be warmed before the group-reagent is added), which 
usually causes aggregation of the particles of a precipitate, and 
hence facilitates the passage of liquids. 

Division of Work. — It is immaterial whether a solution be first 
divided into group-precipitates or each precipitate be examined as 
soon as produced : if the former method be adopted, confusion will 
be avoided by labelling or marking the funnels or papers holding 
the precipitate "the HClppt.," "the H 2 Sppt.," and so on. 

The colors and general appearance of the various sulphides and 
hydrates precipitated should be borne in mind, as the absence of 
other bodies, as well as the presence of those thrown down, is often 
at once thus indicated. 

Application of confirmatory tests must be frequent. 

Results of analyses should be recorded neatly in a memorandum- 
book— a, for correction and* endorsement by the teacher ; b, for 
future reference by the student, or, c, by those who may need evi- 
dence respecting his labors ; and, d, promote mental orderliness. 

The various reactions which occur in an analysis have already 
come before the reader in going through the tests for the individual 
metals or in other analytical operations ; it is unnecessary, there- 
fore, again to draw out equations or diagrams. But the reactions 
should be thought over, and, if not perfectly clear to the mind, be 
written out again and again till thoroughly understood. 



QUESTIONS AND EXERCISES. 

By what process is silver obtained from argentiferous galena ? — What 
weight of English silver coin will yield one pound of pure silver nitrate? 
— How may the metal be recovered from impure silver salts? — Give a 
diagram showing the formation of silver nitrate. — Describe the reaction 



226 THE METALLIC EADICALS. 

of lime-water and silver nitrate. — Mention the chief test for silver, and 
state how silver salts may he distinguished from those of lead and mer- 
cury. — Name the antidote for silver. — Give processes for the qualitative 
analysis of liquids containing the following substances: a. Antimony 
and Mercurous salt. b. Lead and Calcium, c. Silver and Mercurous 
salt. d. Lead and Mercuric salt. e. Copper and Arsenum. /. Arsenum 
and Antimony, g. Aluminium and Zinc. h. Iron and Copper, i. Mag- 
nesium, Calcium, and Potassium, j. Silver, Antimony, Zinc, Barium, 
and Ammonium. — Enumerate the so-called group-tests for the metals. — 
Give a general sketch of the method of analyzing a solution suspected to 
contain two or more salts of common metals. Classify the common 
metals according to their analytical relations. 



METALS OF MINOR PHARMACEUTICAL 
IMPORTANCE. 

Thus far lias been considered, somewhat in detail, the chemistry 
of the common metals, salts of which are frequently used in medi- 
cine or in testing medicinal substances. These are, exclusive of 
hydrogen, 

Potassium, Barium, Zinc, Arsenum, Mercury, 

Sodium, Calcium, Aluminium, Antimony, Lead, 

Ammonium (?), Magnesium, Iron, Copper, Silver. 

Of the remaining metals, eight, exclusive of molybdenum, are 
mentioned in the British and United States Pharmacopoeias — 
namely : 

Lithium, Manganese, Tin, Platinum, 

Cerium, Chromium, Gold, Bismuth. 

Compounds of four more are sufficiently common to occasionally 
come under notice : 

Strontium, Cobalt, Nickel, Cadmium. 

These twelve metals of minor pharmaceutical interest may now 
be shortly studied, a few only of the reactions of each (just those 
mentioned in the following pages) being performed. When all have 
been thus treated their respective positions in the analytical groups 
will be indicated, and a tabular scheme be given by which an 
analysis of a solution containing any metal may be effected. Thus, 
step by step, we may learn how to analyze almost any substance 
that may occur, and know to what extent the presence of a rarer 
will interfere with the ordinary tests for a common element ; addi- 
tional illustrations of the working of chemical laws will be acquired 
and the store of chemical and pharmaceutical facts be increased. 
The opportunity thus afforded for improvement in habits of neatness 
of manipulation, in precision, and in power of classification furnishes 
another and no mean reason why such experiments should be pros- 
ecuted, the direct value of which may not be considerable to medical 
and pharmaceutical learners. 



LITHIUM. 227 

LITHIUM. 

Symbol, Li. Atomic weight, 7. 

Lithium is widely distributed in nature, but usually in minute 
proportions compared with other elements. A trace of it may be 
found in most soils and waters, a Cornish spring containing even 
considerable quantities as chloride. 

One salt used in medicine is the Citrate (Li 3 C 6 H 5 7 ) {Lithii 
Citras, U. S. P., lithium citrate), occurring in white deliquescent 
crystals or powder, prepared by dissolving 50 grains of the carbon- 
ate (Li 2 C0 3 ) and 90 of citric acid (50 to 95 if both are quite pure) 
in 1 ounce of water, evaporating to a low bulk, and setting aside in 
a dry place to crystallize, or at once evaporating to dryness and 
powdering the residue. The crystals have the formula Li 3 C 6 H 5 7 ,- 
4H 2 0; dried at 212° F., Li 3 C 6 H 5 7 ,H 2 (Umney). It is very sol- 
uble in water, but almost insoluble in alcohol and ether. 

3Li 2 C0 3 + 2H 3 C 6 H"50 7 = 2Li 3 C 6 H 5 7 -f 3H 2 + 3C0 2 

Lithium Citric acid. Lithium citrate. Water. Carbonic 

carbonate. acid gas. 

The effervescent lithium citrate is also official {Lithii Citras 
Effervescens, U. S. P.). It is prepared similarly to other effervescing 
preparations. 

The benzoate {Lithii Benzoas, LiC 7 H 5 2 , U. S. P.), bromide 
{Lithii Bromidum, LiBr, U. S. P.), and salicylate {Lithii Salicylas, 
LiC 7 H 5 3 , U. S. P.) may be similarly prepared from the respective 
acids. 

The above-named lithium salts are officially tested as follows, the 
bromide being acted upon directly without ignition : 

" On dissolving the residue left on ignition (of either salt) in 
diluted hydrochloric acid, and evaporating the filtered solution to 
dryness, 1 part of the residue should be completely soluble in 5 
parts of absolute alcohol, and the addition of an equal volume of 
ether to the alcoholic solution should produce no precipitate (salts 
of alkalies). On dissolving another portion of the residue in a small 
quantity of water, the solution should produce no precipitate with 
test-solution of ammonium oxalate (salts of alkaline earths). The 
aqueous solution should remain unaffected by hydrosulphuric acid 
or ammonium sulphide (abs. of metals)." — U. S. P. 

The carbonate {Lithii Carbonas, U. S. P.) is a white granular 
powder obtained from the minerals which contain lithium — namely, 
lepidolite (from Aerrfc, lepis,- a scale, and lidog, lithos, a stone ; it has 
a scaly appearance), triphane (from rpetg, treis, three, and <f>aiva), 
phaino, 1 shine) or spodumene (from crrroJow, spodoo, I reduce to 
ashes, in allusion to its exfoliation in the blowpipe-flame), and 
petalite (from -Kkrakov^ petalon, a leaf; its character is leafy and 
laminated). Each contains aluminium silicate, with potassium 
fluoride and lithium in the case of Austrian lepidolite, which is the 
most abundant source, and sodium and lithium silicate in the others. 
The lepidolite is decomposed by sulphuric acid, alumina, etc. pre- 
cipitated by ammonia ; the nitrate evaporated and the residue* 



228 THE METALLIC RADICALS. 

ignited ; the resulting sulphates dissolved in water, and the lithium 
precipitated by a carbonate. The preparation of common alum is 
sometimes made a part of the factory processes, and other obvious 
modifications may be introduced. " If 0.5 gm. of lithium carbonate 
be dissolved in 2 cc. of hydrochloric acid, and the clear solution be 
evaporated to dryness, the dry residue should completely dissolve in 
3 cc. of absolute alcohol, and an addition of 3 cc. of ether should 
not render the solution turbid (limit of other alkalies). 0.5 gm. of 
the dry carbonate, mixed with 20 cc. of water, should require for 
complete neutralization not less than 13.4 cc. of normal sulphuric 
acid (corresponding to at least 98.98 per cent, of the pure salt), 
methyl-orange being used as indicator." — U. S. P. Liquor Lithice 
Effervescens, B. P., is a solution of 10 grains of lithium carbonate 
in 1 pint of water charged with five times its volume of carbonic 
acid gas and kept in ordinary aerated-water bottles. " Half a pint, 
evaporated to dryness, yields 5 grains of a white solid residue, 

answering to the tests for lithium carbonate 10 grains of 

the latter salt, neutralized with sulphuric acid and afterward heated 
to redness, leaves 14.86 grains of dry lithium sulphate, which, when 
redissolved in distilled water, yields no precipitate with ammonium 
oxalate or solution of lime," indicating absence of calcium and 
aluminium salts. Lithium citrate should yield by incineration 52.8 
per cent, of white lithium carbonate. According to C. N. Draper, 
lithium carbonate is soluble in 68 parts of water at 15° C. and 131 
at 100° C. 

Lithium urate * is more soluble than sodium urate ; hence lithium 
preparations are administered to gouty patients in the hope that 
sodium urate, with which such systems are loaded, may become 
lithium urate and be removed. 

In chemical position lithium stands between the alkaline and the 
alkaline-earth metals, its hydrate, carbonate, and phosphate being 
slightly soluble in water. The double platinum and lithium chlo- 
ride also is soluble in water. The atom of lithium is univalent, I/. 

Analytical Reaction. — Moisten the end of a platinum wire 
with solution of a minute particle of solid lithium salt, and 
introduce it into the flame of a Bunsen burner or other almost 
colorless flame (spirit-lamp or blowpipe flame) ; a magnificent 
crimson tinge is imparted. 

The light thus emitted by ignited lithium vapor is of a purer scar- 
let than that given by strontium, the next element. When the 
flames are examined by spectral analysis (physically analyzed by a 
prism), the red rays are, in the case of strontium, found to be asso- 
ciated with blue and yellow, neither of which is present in the 
lithium light, blue lithium rays only appearing at temperatures 
much higher than those of the air-gas flame, or, indeed, any other 
ordinary flame. 

* Urates will be considered subsequently in connection with uric acid. 



STKONTIUM. 229 

STRONTIUM. 

Symbol, Sr. Atomic weight, 87.4. 

Source. — Strontium is not widely distributed in nature 5 but the 
carbonate (SrC0 3 ), known as strontianite, and the sulphate (SrS0 4 ), 
known as celestine (from caelum, the sky, in allusion to its occasional 
bluish color), are by no means rare minerals. 

Strontium Bromide, SrBr 2 ,6H 2 (Strontii Bromidum, U. S. P.), 
occurs as colorless deliquescent hexagonal crystals, soluble in water 
and alcohol, insoluble in ether. It may be prepared by dissolving 
the carbonate [strontianite) in hydrobromic acid or roasting the 
sulphate with coal (celestine), and treating the resulting sulphide 
with hydrobromic acid. 

SrS + 2HBr = SrBr + H 2 S. 

Strontium Iodide, SrI 2 6H 2 (Strontii Iodidum, U. S. P.), occurs in 
crystals similar to the bromide ; soluble in water and alcohol, but 
only slightly in ether. It may be prepared similarly to bromide, 
using hydriodic instead of hydrobromic acid. 

Strontium Lactate. (See Index.) 

Strontium salts are used by firework-manufacturers in preparing 
red fire. The color they impart to flame is a beautiful crimson — 
ignited strontium vapor emitting red rays, as already explained. 
Strontium nitrate (Sr2N0 3 ) is best for pyrotechnic compositions, its 
oxygen enabling it to burn freely when mixed with charcoal, sul- 
phur, etc. It or any salts may be obtained, as described above, by 
dissolving the carbonate or sulphide in an acid. 

The position of strontium, among the chemical elements is between 
barium and calcium ; its sulphate is extremely sparingly soluble in 
water. Its atom, like those of barium and calcium, is bivalent (Sr // ). 

Analytical Reactions (Tests). 

First Analytical Reaction. —To a solution of a strontium salt 
(Sr2N0 3 or SrCl 2 ) add ammonium carbonate ; a white precip- 
itate (strontium carbonate, SrC0 3 ) falls. 

Second Analytical Reaction. — To a solution of a strontium 
salt add sulphuric acid previously so diluted that it will not 
precipitate calcium salts, or add an equally dilute solution of 
any sulphate — e. g. that of calcium itself; a white precipitate 
(strontium sulphate, SrS0 4 ) falls. The formation of this pre- 
cipitate is promoted by stirring and by setting the liquid aside 
for some time. (Barium is precipitated immediately under 
similar circumstances.) 

Third Analytical Reaction. — To a dilute solution of a stron- 
tium salt add yellow chromate (K 2 Cr0 4 or KNH 4 O0 4 ) ; no 
precipitate falls. 

Barium may be separated from strontium by potassium chromate, 
that reagent at once precipitating barium from aqueous or acetic 
11 



230 THE METALLIC RADICALS. 

solutions. The value of the reaction is enhanced if acetic acid or 
ammonium acetate be present, strontium chromate being far more 
soluble in such fluids than in water (Ransom). It is also more solu- 
ble in cold than in hot fluids. 

Fourth Analytical Reaction.— Insert a fragment of a stron- 
tium salt in the blowpipe flame or other equally colorless flame, 
or hold the end of a platinum wire dipped into a strontium 
solution in the flame ; a crimson color is imparted. 

Other Analytical Reactions. — Alkali-metal phosphates, arsen- 
ates, and oxalates give white insoluble precipitates with stron- 
tium, as with barium and calcium. 



Cerium, Ce ; At. wt., 141. — This element occurs in the mineral 
cefite (a silicate of iron, calcium, and the three rare metals cerium, 
lanthanium, and didymium) ; also occasionally as impure fluoride, 
carbonate, and phosphate. Cerium oxalate, a white granular 
powder, is the only official salt ; it may be obtained from cerite by 
boiling the powdered mineral in strong hydrochloric acid for several 
hours, evaporating, diluting, and filtering to separate silica ; adding 
ammonia to precipitate hydrates of all the metals except calcium ; 
filtering off, washing, redissolving in hydrochloric acid, and adding 
oxalic acid to precipitate cerium oxalate. The preparation will still 
contain lanthanium and didymium oxalates ; it is therefore strongly 
calcined, the resulting lanthanium and didymium oxides dissolved 
out to some extent by boiling with a concentrated solution of ammo- 
nium chloride, the residual cerium oxide dissolved in boiling hydro- 
chloric acid, and ammonium oxalate added to precipitate cerium oxalate 
(Ce /// 2 3C 2 4 ,9H 2 0). According to Hartley, the precipitated hydrates 
should be treated with chlorine, by which eerie hydrate is left 
insoluble and the other hydrates converted into soluble hypochlorites. 

Cerium oxalate (Cerii Oxalas, Oxalate of Cerium, or Cerium 
Oxalate, U. S. P.) is decomposed at a dull-red heat, 48 per cent, of a 
yellow, or, more generally, salmon-colored, mixture of oxides remain- 
ing. Usually the didymium present gives the ignited residue a red- 
dish or reddish-brown color. The oxides are soluble in boiling 
hydrochloric acid (without effervescence, indicating, indirectly, 
absence of earthy and other carbonates or oxalates), and the solu- 
tion gives, with excess of a saturated solution of potassium sulphate,' 
a crystalline precipitate of cerium and potassium sulphate. Alumina 
mixed with cerium oxalate may be detected by boiling with solu- 
tion of potash, filtering, and adding excess of solution of ammonium 
chloride, when a white flocculent precipitate (aluminium hydrate) 
will be obtained. The oxalic radical is recognized by neutralizing 
the potash solution by acetic acid and adding calcium chloride ; a 
white precipitate (calcium oxalate) falls : this precipitate, though 
insoluble in acetic, should be wholly dissolved by hydrochloric acid. 
Acid or neutral cerium solutions give with sodium acetate and 
hydrogen peroxide a brownish-red color (Hartley). 



MANGANESE. 231 

According to H. Gr. Greenish, most samples of the oxalate contain 
as impurities traces of lead, iron, and magnesium. 

MANGANESE. 

Symbol, Mn, Atomic weight, 55. 

Source. — Manganese is a constituent of many minerals, and, as 
black oxide (Mn0 2 ) {Mangani Dioxidum, U. S. P., "containing at 
least 66 per cent, of the pure dioxide, Mn0 2 ; Mangani Oxidurn 
Nigrum, 1880), or pyrolusite (from 7rvp,pur, fire, and Ivaiq; lusis, a 
loosing or resolving, in allusion to the readiness with which it is 
split up by heat into a lower oxide and oxygen), is met with in 
abundance in the south-west of England, Aberdeenshire, and most 
countries of Europe. It occurs as a steel-gray mass of prismatic 
crystals or in black shapeless lumps. 

The chemical position of manganese is close to iron and three other 
metals still to be considered — cobalt, nickel, and chromium. Its 
atom apparently has sexivalent affinities, as seen in potassium 
manganese (K 2 MnOJ, but commonly it is quadrivalent (Mn //// ) or 
bivalent (Mn"). 

Uses. — Metallic manganese, which may be isolated by aid of 
sodium, is used in alloy with iron in the manufacture of some 
varieties of steel. The black oxide is an important agent in the 
production of chlorine and in the preparation of green and purple 
disinfecting manganates, purple glass, and black glaze for earthen- 



Reactions having both Synthetical and Analytical 
Interest. 

First Reaction. — Boil a little black manganese oxide with 
hydrochloric acid in a fume-chamber until chlorine ceases to 
be evolved ; filter ; the filtrate is a solution of manganous chlo- 
ride (MnCl 2 ). 

Mn0 2 + 4HC1 = MnCl 2 + 2H 2 + Cl 2 . 

This is the reaction commonly applied in the preparation of 
chlorine gas. It is also a ready method of preparing a manganous 
salt for analytical experiments. Coupled with the application of 
reagents to the filtrate, the reaction is that by which a black powder 
or mineral would be recognized as black manganese oxide. Black 
manganese oxide dissolves in cold hydrochloric acid, forming a 
dark-brown solution of a higher chloride or chlorides, MnCl 3 ,- 
Mn 2 Cl 7 , or, possibly, MnCl 4 . 

Second Reaction. — Heat a manganese compound with a grain 
or two of potassium carbonate and hydrate and a fragment of 
potassium nitrate or chlorate on platinum-foil in the blowpipe 
flame ; a green mass containing potassium manganate (K 2 Mn0 4 ) 
results. Boil the foil in water ; the green manganate dissolves, 



232 THE METALLIC KADICALS. 

the fluid soon changing to solution of the purple potassium per- 
manganate (K 2 Mn 2 8 ). 

Carefully performed, this is a delicate test for manganese. 

The reaction is similar to that by which potassium permanganate 
(Potassii Permanganas, U. S. P.) is directed to be prepared for use 
in volumetric analysis. Liquor Potassii Permanganatis, B. P., is 
a solution of 88 grains of potassium permanganate in 1 pint of dis- 
tilled water. Equations showing the action which occurs in making 
the salt have already been given in connection with the compounds 
of potassium (vide p. 77). The proportions of ingredients and 
details of the operation are as follows : 

Reduce 3J parts (for experiment each "part" may be £ of an 
ounce or 4 grammes) of potassium chlorate to fine powder, and mix 
it with 4 of black manganese oxide ; put the mixture into a porce- 
lain basin, and add to it 5 parts of solid caustic potash previously 
dissolved in 4 parts of water. Evaporate to dryness, stirring dili- 
gently to prevent spurting. Pulverize the mass, put it into a cov- 
ered Hessian or Cornish crucible, and expose it to a dull-red heat 
(not higher) for an hour (twenty or thirty minutes for quantities of 
1 or 2 ounces), or till it has assumed the condition of a semi-fused 
mass. Allow to cool, pulverize, and boil with about 30 parts of 
water. Let the insoluble matter subside, decant the fluid, boil 
again with about 10 parts of water, again decant, neutralize the 
united liquors accurately with diluted sulphuric acid (or, better, car- 
bonic acid gas), and evaporate till a pellicle forms. Set aside to 
cool and crystallize. Drain the crystalline mass, boil it in 6 parts 
of water, and strain through a funnel the throat of which is lightly 
obstructed by a little asbestos or gun-cotton. Let the fluid cool 
and crystallize, drain the dark-purple, slender, prismatic crystals, 
and dry them by placing under a bell-jar over a vessel containing 
sulphuric acid. 

Instead of converting the manganate by ebullition and neutraliz- 
ing the free alkali by acid, by which one-third of the manganese is 
lost, chlorine may be passed through the cold solution until the 
green color is entirely changed to purple. 

2K 2 Mn0 4 + Cl 2 = K 2 Mn 2 8 + 2KC1. 

Solutions of the potassium and sodium manganates are in common 
use as green and purple disinfecting fluids. They act by oxidizing 
organic matter, the manganic or permanganic radical being reduced 
to .black manganic oxide or even a lower oxide. The reason for 
using asbestos instead of paper in filtering the solutions will now 
be understood. 

The changes in color which the green mass of the above process 
undergoes when dropped into warm water produced for it the old 
name of mineral chameleon. 

Third Reaction. — Make a borax bead by heating a fragment 
of the salt on the looped end of a platinum wire in the blow- 
pipe flame until a clear transparent globule is obtained. Place 



MANGANESE. 233 

on the bead a minute portion of a manganese compound or 
touch it with a drop of solution. Again fuse the borax ; a 
bead of a violet or amethystine tint is produced. 

This is a good analytical reaction. It has also synthetical inter- 
est, illustrating the use of black manganese oxide in producing 
common purple-tinted glass. 

Expose the bead to the reducing part of the flame (p. 135), 
the part nearer to the blowpipe, where there are highly-heated 
hydrocarbon gases greedy of oxygen ; the color disappears. 

This is owing to the reduction of the manganic compound to a 
manganous condition, in which it no longer possesses peculiar color- 
ing-power. This action also illustrates the use of black manganese 
oxide in glass-manufacture. Glass, when first made, is usually of 
a green tint, owing to the presence of ferrous impurities : the addi- 
tion of manganic oxide to the materials converts the ferrous into 
ferric compounds, which have comparatively little colorific power, 
it itself being thereby reduced to manganous oxide, which also gives 
but little color. If excess of manganic oxide be added, a purple 
tint is produced. 

Reactions having Analytical Interest (Tests). 

Fourth Reaction. — Through a solution of a manganous salt 
acidified by hydrochloric acid pass suphuretted hydrogen ; no 
decomposition occurs. Add ammonia ; the ammonium sulphy- 
drate thus formed causes the precipitation of a yellowish-pink 
or flesh-tinted precipitate (manganous sulphide, MnS, in a 
hydrous state). . 

This reaction is characteristic, manganese sulphide being the only 
flesh-colored sulphide known. The salt used may be the manganous 
chloride obtained in the first reaction, but such crude solutions 
usually give a black precipitate with ammonium sulphydrate, owing 
to the presence of iron. The latter element may be precipitated, 
however, on adding excess of ammonia (and rapidly filtering, or 
oxygen will be absorbed and most of the manganese also be pre- 
cipitated), or on boiling the manganous solution with a very little 
sodium carbonate, which attacks the ferric salt in preference to the 
manganous. Pure manganous chloride may be similarly obtained 
on boiling the impure solution with manganous carbonate ; the lat- 
ter decomposes the ferric chloride, with production of ferric hydrate 
and more manganous chloride and evolution of carbonic acid gas. 

To the recently precipitated manganous sulphide add acetic acid ; 
it is dissolved. 

This solubility enables manganese to be separated from nickel, 
cobalt, and zinc, whose sulphides are insoluble in weak acetic acid. 
To express the fact in another way : manganese is not precipitated 
by sulphuretted hydrogen from a solution containing free acetic 
acid. 



234 THE METALLIC RADICALS. 

Fifth Reaction. — To solution of a manganous salt add 
ammonia ; a white precipitate (manganous hydrate, Mn2HO) 
falls. Add excess of ammonia ; some of the precipitate is dis- 
solved, and may be detected in the quickly-filtered solution by 
ammonium sulphydrate. But both precipitate and solution 
rapidly absorb oxygen, the manganese passing into a more 
highly oxidized condition, in which it is insoluble in ammonia. 
The fixed alkalies give a similar precipitate insoluble in excess. 
The precipitate rapidly absorbs oxygen, becomes brown, and 
gradually passes into a higher oxide. 

Sixth Reaction. — To a solution of a manganous salt add 
diluted nitric acid, and either red lead or the puce-colored lead 
oxide or peroxide, and then boil ; a red tint, said to be due to 
permanganic acid, is imparted to the liquid. If chlorides are 
present, the manganese, etc. should be separated by potash or 
soda, the precipitate be well washed, dissolved in nitric acid, 
and then the oxide be added (Crum). 

Seventh Reaction. — Heat a little manganese dioxide in a test- 
tube with sulphuric acid ; oxygen is evolved and manganese 
sulphate formed {Mangani Sulphas, MnS0 4 ,4H 2 0, U. S. P.) ; 
add water, boil, filter, evaporate, and set aside to crystallize. 
Larger quantities are made in a similar manner. 

Manganese sulphate (MnS0 4 ,5H 2 0) occurs in colorless or pale 
rose-colored, transparent crystals, which, when deposited from a 
solution at a temperature between 68° and 86°, have the form of 
right rhombic prisms and contain four molecules of water (U. S. P.). 
This salt is very soluble in water. Other sulphates containing 1, 2, 
3, and 9 of water are known. The solution is not colored by tincture 
of nutgall (a black shows iron), but affords with caustic alkalies a 
white precipitate (Mn2HO), which, by exposure to the air, soon 
absorbs oxygen and becomes brown. Ammonium sulphydrate 
throws down a flesh-colored precipitate (MnS), and potassium ferro- 
cyanide a white one (Mn 2 Fcy). 

Many other reactions occur between manganese salts and 
various reagents, but are of no particular synthetical or ana- 
lytical interest. 

COBALT AND NICKEL. 

Kruss and Schmidt state that these very closely allied metals, as 
hitherto known, are not true elements, but contain a third element, 
the oxide of which resembles, yet distinctly differs from, alumina 
and zinc oxide. 

COBALT. 

Symbol, Co. Atomic weight, 58.6. 

Source. — Cobalt occurs sparingly in nature as the arsenide 



COBALT. 235 

(CoAs 2 ), or tin-white cobalt, and occasionally as a double arsenide 
and sulphide (CoAs 2 ,CoS 2 ), or cobalt-glance (from glanz, brightness, 
in allusion to its lustre). 

Uses. — Its chief use is for coloring glass blue. Cobalt is also the 
coloring constitueut of smalt (from smelt, a corruption of melt), a 
finely-ground sort of glass used as a blue pigment by paper-stainers 
and others, and employed also by laundresses to neutralize the yellow 
tint of washed linen. 

The salts of cobalt may be obtained from the oxide (CoO), and the 
oxide from zaffre, a mixture of sand and roasted ore. 

Quantivalence. — The atom of cobalt often exhibits quadrivalent 
affinities, but still more often exerts only bivalent powers (Co"). 
Cobalt has analytical relations with zinc, nickel, and manganese. 

Analytical Reactions (Tests). 

First Analytical Reaction, — Pass sulphuretted hydrogen 
through an acidified solution of a salt of cobalt — the chloride 
(CoCl 2 ) or nitrate (Co2N0 3 ), for example ; no decomposition 
occurs. Add ammonia ; the ammonium sulphydrate thus 
formed causes a black precipitate (cobalt sulphide, CoS). (The 
moist precipitate slowly absorbs oxygen from the air, yielding 
some cobalt sulphate, CoS0 4 .) 

Second Analytical Reaction. — Add ammonia gradually to a 
cobalt solution ; a blue precipitate (impure cobalt hydrate, 
Co2HO) falls. Add excess of ammonia ; the precipitate is 
dissolved, yielding a liquid somewhat more reddish-brown than 
the original solution. A similar precipitate is given by the 
fixed alkalies, insoluble in excess. 

Third Analytical Reaction. — Make a borax bead by heating 
a fragment of the salt on the looped end of a platinum wire in 
the blowpipe flame until a clear transparent globule is obtained. 
Place on the bead a minute portion of any cobalt compound or 
touch it with a drop of solution. Again fuse the borax ; a 
blue bead results. 

This is a delicate test for cobalt. From what has been said pre- 
viously it will be seen that this experiment has also considerable 
synthetical interest. 

Fourth Analytical Reaction. — To a solution of a salt of 
cobalt add a few drops of hydrochloric acid, then excess of 
solution of potassium -cyanide, and boil for ten minutes; oxy- 
gen is absorbed, and potassium cobalticyanide (K 6 Co 2 Cy 12 ) 
formed. Add hydrochloric acid, and boil the mixture (in a 
fume-cupboard, to avoid inhalation of any hydrocyanic acid) ; 
the excess of potassium cyanide is thus decomposed, the cobal- 
ticyanide unaffected. Now add excess of solution of potash; 



236 THE METALLIC KADICALS. 

the potassium cobalticyanide is probably decomposed, but the 
cobalt remains dissolved in the alkaline liquid. Nickel under 
similar circumstances is precipitated, the reaction thus afford- 
ing means of separating these closely-allied metals from each 
other. 

Other reactions between the cobalt solution and different reagents 
may be performed, and various precipitates obtained, but these 
have no special analytical interest. 

Invisible Ink. — Many salts of cobalt containing water of crys- 
tallization are light red, the anhydrous more or less blue. Prove 
this by writing some words on paper with a solution of chlo- 
ride of cobalt sufficiently dilute for the characters to be invis- 
ible when dry : hold the sheet before a fire or over a flame ; 
the letters at once become visible, distinct, and of a blue color. 
Breathe on the words or set the sheet aside for a while ; the 
characters are once more invisible, owing to absorption of 
moisture. Hence solution of cobalt chloride forms one of the 
so-called sympathetic inks. 

NICKEL. 

Symbol, Ni. Atomic weight, 58.6. 

The ores of nickel and cobalt are commonly associated in nature. 
Indeed, it is from speiss, an arsenio-sulphide of nickel obtained in 
the manufacture of a pigment of cobalt, smalt, already mentioned, 
that much of the nickel met with in commerce has hitherto been 
obtained. Garnierite, silicate of magnesium and of nickel, con- 
taining no cobalt, is also a valuable source of nickel. Nickel is 
used in the preparation of the white alloy known as German or nickel 
silver and for plating iron. 

Quantivalence. — Nickel exerts bivalent activity (Ni // ) in its 
ordinary compounds. Its salts and their solutions are usually 
green. They are chiefly made, directly or indirectly, from the 
metal itself. 

Analytical Reactions (Tests). 

First Analytical Reaction. — Pass sulphuretted hydrogen 
through an acidified solution of a salt of nickel — chloride 
(NiCl 2 ), nitrate (Ni2N0 3 ), or sulphate (NiSo 4 ) ; no decomposi- 
tion occurs. Add ammonia ; the ammonium sulphydrate 
formed causes a black precipitate (nickel sulphide, NiS). 

Note. — When nickel sulphide is precipitated by the direct addi- 
tion of the common yellow solution of ammonium sulphydrate, which 
always contains free sulphur, there is much difficulty in filtering the 
mixture, owing to the slight solubility of nickel sulphide in the reagent 
and the formation of some nickel sulphate (NiSOJ, oxygen being 



NICKEL. 237 

absorbed from the air by the sulphide. This may be avoided by 
warming the mixture and using freshly-made ammonium sulphydrate, 
in which the nickel sulphide is insoluble ; or, when practicable, the 
salt of nickel may be precipitated from an ammoniacal solution by 
sulphuretted hydrogen. 

Second Analytical Reaction. — Add ammonia, drop by drop, 
to a nickel solution ; a pale-green precipitate (nickel hydrate, 
Ni2HO) falls, especially on boiling the mixture. Add excess 
of ammonia ; the precipitate dissolves, yielding a bluish rather 
than the original green-colored solution. A similar precipitate 
is given by the fixed alkalies, insoluble in excess. 

Third Analytical Reaction. — Nickel salts color a borax bead, 
when hot, a reddish-yellow tint ; the reaction is not very ser- 
viceable analytically. 

Fourth Analytical Reaction. — To a solution of a salt of 
nickel add solution of potassium cyanide ; nickel cyanide 
(NiCy,) is precipitated. Add excess of solution of potassium 
cyanide ; the precipitate is dissolved with formation of double 
nickel and potassium cyanide (NiCy 2 ,2KCy). Next add hydro- 
chloric acid, and boil the mixture (in a fume-cupboard, adding 
a little hydrochloric acid from time to time until all smell of 
hydrocyanic acid has disappeared). Lastly, add excess of solu- 
tion of potash ; pale-green nickel hydrate is precipitated. 

Qualitative Separation of Cobalt and Nickel. 

(This process requires much practice for its successful performance, and 
need not be attempted by impils whose studies are restricted to medicine or 
pharmacy.) 

The foregoing reaction serves for the separation of nickel from 
cobalt. On adding excess of potassium cyanide to a very slightly 
acidified solution containing the two metals, and well boiling, a 
solution of potassium cobalticyanide and double nickel and potas- 
sium cyanide results. On boiling with excess of hydrochloric acid 
the nickel salt is converted into chloride, and this, with the potas- 
sium cobalticyanide, gives a milky-looking precipitate of nickel 
cobalticyanide (Ni 3 Co 2 Cy 12 ), insoluble in the acid. On then adding 
excess of potash the nickel cobalticyanide is decomposed, nickel 
hydrate remaining as a green flocculent precipitate and potassium 
cobalticyanide going into solution. After filtering off the nickel, 
cobalt is detected in the filtrate by evaporating to dryness and test- 
ing the residue with borax in the blowpipe flame. 

Other Reactions between a nickel solution and various 
reagents give, in many cases, insoluble precipitates which, from 
their green color, are occasionally useful in distinguishing nickel 
from allied elements. 



11* 



238 THE METALLIC KADICALS. 

CHROMIUM. 

Symbol, Cr. Atomic weight, 52.5. 

Source. — The chief ore of chromium is chrome ironstone (a com- 
pound of the metallic oxides FeO, Cr 2 3 ), occurring chiefly in the 
United States and Sweden. In constitution it seems to resemble 
magnetic iron ore (FeO,Fe 2 3 ). The metal may be isolated by aid 
of sodium. 

Preparation of Red Potassium Chromate.— On roasting the pow- 
dered ore with potassium carbonate and nitre, yellow potassium 
chromate (K 2 Cr0 4 ) is obtained ; the mass, treated with acid, yields 
red or bichromate (K 2 Cr0 4 ,Cr0 3 ) (Potassii Bichromas, U. S. P.), the 
old dichromate or bichromate of potash ; from this other chromates 
are prepared, and by reduction, as presently explained, the salts of 
chromium itself. The yellow and orange lead chromates are used 
as pigments. 

Notes.— Red potassium chromate is a somewhat abnormal salt, 
containing, possibly, neutral chromate associated with chromic anhy- 
dride, and hence termed potassium anhydrochr ornate (K 2 Cr0 4 ,Cr0 3 ), 
or potassium pyrochromate (K 2 Cr 2 7 ). The value of chromates as 
chemical reagents is alluded to in connection with chromate of 
barium (pp. 105-117). Heated strongly in a crucible, red potas- 
sium chromate splits up into yellow chromate, glistening chromium 
oxide, and oxygen. Red ammonium chromate by heat yields several 
times its volume of bluish-green chromium oxide, water, and nitro- 
gen : (NH 4 ) 2 Cr0 4 ,Cr0 3 = Cr 2 3 + 4H 2 + N r 

Quantivalence. — Chromium stands in close chemical relation to 
iroD, aluminium, and manganese. Its atom is sexivalent if the 
formula of the fluoride (CrF 6 ) be correct. Like iron and aluminium, 
it is trivaient, as seen in chromic chloride (Cr 2 Cl 6 ), but sometimes 
exerts only bivalent activity, as in chromous chloride (OrCl 2 ). 

Passage of Chromium from the Acidulous to the Basylous Side 
of Salts. — Through an acidified solution of red potassium chro- 
mate pass sulphuretted hydrogen ; sulphur is deposited, and a 
green salt of chromium remains in solution— chloride (Cr 2 Cl 6 ) 
if hydrochloric acid be used, and sulphate (Cr 2 3S0 4 ) if sul- 
phuric be the acid employed. Boil the liquid to expel excess 
of sulphuretted hydrogen, filter, and reserve the solution for 
subsequent experiments. (For an equation explanatory of this 
reaction see p. 239). Alcohol, sugar, or almost any substance 
which is tolerably liable to oxidation will answer as well as sul- 
phuretted hydrogen. 

Chromium Sulphate (Cr 2 3S0 4 ), like aluminium sulphate (A1 2 3S0 4 ), 
unites with alkali-metal sulphates to form alums, which resemble 
common alum both in crystalline form and in structure ; they are of 
a purple color. 

Reactions. 

Chromium as Chromic Acid or other Chromate. — This is the 



CHROMIUM. 239 

state in which chromium will usually be met with, the most 
common salt being the red chromate of potassium or bichro- 
mate. Mix four volumes of a cold saturated aqueous solution 
of red potassium chromate with five of oil of vitriol ; on cooling, 
chromic anhydride or anhydrous chromic acid (Cr0 3 ) (Acidum 
Chromicum, U. S. P.) separates in crimson needles. After well 
draining, the crystals may be freed from adhering sulphuric 
acid by washing once or twice with nitric acid : the latter may 
be removed by passing dried and slightly warmed air through 
a tube containing the crystals. It may also be freed from sul- 
phuric acid by one or two recrystallizations. In contact with 
moisture chromic anhydride takes up water and forms solution 
of true chromic acid (H 2 Cr0 4 ), 1 part of the anhydride and 3 
of water forming the Liquor Acldi Chromici, B. P. Chromic 
anhydride is a powerfully corrosive oxidizing agent ; it melts 
between 356° and 374° F., and at a higher temperature decom- 
poses, yielding chromium oxide and oxygen ; it oxidizes organic 
matter with great violence, spontaneous ignition sometimes 
resulting. 

The oxygen in chromic acid and other chromates, and in manga- 
nates, permanganates, black manganese oxide, and puce-colored lead 
oxide, is in a physically different state to that in hydrogen peroxide, 
barium peroxide, and similar compounds. On bringing chromic 
acid or the above acidified solution of red potassium chromate into 
contact with solution of hydrogen peroxide a strong effervescence 
of oxygen ensues. According to Schonbein and Brodie, the oxygen 
in chromic acid is in the negative or ozonic state, while that of 
hydrogen peroxide is in the positive or so-called antozonic condition. 
Both are equally active, but neutralize each other, forming neutral or 
ordinary oxygen. 

In the analytical examination of solutions containing chro- 
mates the chromium will always come out in the state of green 
chromic hydrate along with ferric hydrate and alumina, the 
prior treatment by sulphuretted hydrogen reducing the chro- 
mium in the molecule to the lower state, thus : 
K 2 Cr0 4 ,Cr0 3 + 8HC1 + 3H 2 S = Cr 2 Cl 6 + 2KC1 + 7H 2 + S 3 . 

Chromium having been found in a solution, its condition as 
chromate may be ascertained by applying to the original solu- 
tion salts of barium, mercury, lead, and silver. (See the 
various paragraphs relating to those metals.) 

Ba2N0 3 gives yellow BaCr0 4 with chromates. 

HgN0 3 « red Hg 2 Cr0 4 

AgN0 3 " red Ag 2 CrO, 

AgN0 3 " red Ag 2 Cr0 4 ,Cr0 3 with bichromates. 

Pb2C 2 H 3 2 " yellow PbCrO, with both. 



240 THE METALLIC RADICALS. 

Barium nitrate does not completely precipitate bichromates, barium 
bichromate being soluble in water ; barium chromate is insoluble in 
water or acetic acid, but soluble in hydrochloric or nitric acid. Mer- 
curous nitrate does not wholly precipitate bichromates : mercuric 
nitrate or chloride only partially precipitates chromates, and does 
not precipitate bichromates. The mercurous chromate is insoluble 
or nearly so in diluted nitric acid. The silver chromates are soluble 
in acids and alkalies. Lead acetate precipitates chromates and 
bichromates, acetic acid being set free in the latter case. 

A delicate reaction for dry chromates will be found in the 
formation of chlorochromic anhydride (Cr0 2 Cl 2 ). A small por- 
tion of the chromate is placed in a test-tube with a fragment 
of dry sodium chloride and a drop or two of sulphuric acid, 
and the mixture heated ; red irritating fumes of chlorochromic 
anhydride are evolved aud condense in dark-red drops on the 
side of the tube. 

Larger quantities are obtained by the same reaction, the operation 
being conducted in a retort with thoroughly dry materials, for the 
compound is decomposed by water. It may be regarded as chromic 
anhydride in every molecule of which an atom of oxygen is displaced 
by an equivalent quantity (two atoms) of chlorine. It is not used 
in medicine, but is of interest to the chemical student as being an 
illustration of a class of similar bodies — chloro-acididous or chloro- 
anhydro compounds. The reaction is also occasionally serviceable 
for the detection of chlorides. 

Analytical Reactions of Chromium Salts (Tests). 

First Analytical Reaction. — To solution of a salt of chromium 
(chloride, sulphate, or chrome alum) add ammonium sulphy- 
drate ; a bulky green precipitate (chromic hydrate, O 2 6H0), 
containing a large quantity of water (seven molecules, 7H 2 0), is 
precipitated. 

Cr 2 Cl 6 + 6NH.HS + 6H 2 = O 2 6H0 + 6NH 4 C1 + 6H 2 S. 

Second Analytical Reaction. — To solution of a chromium salt 
add ammonia ; green chromic hydrate is precipitated, insoluble 
in excess. 

Tliird Analytical Reaction. — To solution of a chromium salt 
add solution of potash or soda, drop by drop ; green chromic 
hydrate is precipitated, "ildd excess of the fixed alkali ; the 
precipitate is dissolved. Well boil the solution ; the green 
chromic hydrate is reprecipitated. 

Iron, chromium, and aluminium salts, chemically so alike, may be 
separated by this reaction. Ferric hydrate is insoluble in solutions 
of the fixed alkalies, cold or hot ; chromium hydrate soluble in cold, 
but not in hot ; aluminium hydrate in both. To a solution contain- 



TIN. 241 

ing all three metals, therefore, add potash or soda, stir, and filter •, 
the iron is thrown out : boil the filtrate and filter ; the chromium 
is thrown out ; neutralize the latter filtrate by acid, and then add 
ammonia ; the aluminium is thrown out. Note, however, that 
ferric hydrate will prevent chromium hydrate being dissolved by 
potash or soda if the ferric hydrate is in considerable excess. 
Before concluding that chromium is entirely absent, the fourth re- 
action should be performed. Iron, chromium, and aluminium 
hydrates are insoluble in ammonia, and may therefore easily be 
separated from the hydrates of the somewhat analogous metals, zinc, 
cobalt, nickel, and manganese. 

Fourth Analytical Reaction. — Add a salt of chromium (either 
of the above precipitates of chromic hydrate or the dry residue 
of the evaporation of a few drops of a solution of a chromium 
salt) to a few grains of nitre and sodium carbonate on platinum- 
foil, and fuse the mixture in the blowpipe flame ; a yellow mass 
(potassium and sodium chromate, KNaCr0 4 ) is formed. Dissolve 
the mass in water, add acetic acid to decompose excess of car- 
bonate, and apply the reagents for chromates. This is a delicate 
and useful reaction if carefully performed. 

TIN. 

Symbol, Sn. Atomic weight, 118. 

Source. — The chief ore of tin is stannic oxide (Sn0 2 ), occurring in 
veins under the name of tin-stone or in alluvial deposits as stream-tin. 
The oldest mines are those of Cornwall. Much tin is now imported 
from Australia. 

Preparation. — The metal is obtained by reducing the roasted and 
washed ore by charcoal or anthracite * coal at a high temperature, 
and is purified by slowly heating, when the pure tin, fusing first, is 
run off, a somewhat less fusible alloy of tin, with small quantities 
of arsenum, copper, iron, or lead, remaining. The latter is known 
as block-tin ; the former, heated till brittle and then hammered or 
let fall from a height, splits into prismatic fragments resembling 
starch or columnar basalt, and is named dropped or grain-tin. 
Good tin emits a crackling noise in bending, termed the " cry " of 
tin, caused by the friction of its crystalline particles on each other. 

Uses. — Tin is an important constituent of such alloys as pewter. 
Britannia metal, solder, speculum-metal, bell-metal, gun-metal, and 
bronze. It is very ductile, and may be rolled into plates or leaves, 
known as tin-foil, varying from ¥ ^ to toVo °f an i ncn i n thickness. 
Common tin-foil, however, usually contains a large proportion of 
lead. The reflecting surface of looking-glasses was formerly always 

* Anthracite (from av6pai-, anthrax, a burning coal), or stone coal, differs 
from the ordinary bituminous or caking coal in containing less volatile 
matter, and therefore in burning without flame. It gives a higher tem- 
perature, and, from its non-caking properties is, in furnace operations, 
more manageable than bituminous coal. 



242 THE METALLIC RADICALS. 

an amalgam of tin and mercury, produced by carefully sliding a 
plate of glass over a sheet of tin-foil on which mercury had been 
rubbed and then excess of mercury been poured ; but pure silver, 
deposited from a solution, is now largely employed. Pins are made 
of brass wire on which tin is deposited. Tin-plate, of which common 
utensils are made, is iron alloyed with tin by dipping the acid- 
cleansed sheet into vessels of melted tin covered with melted zinc 
chloride in the one case and oil in the other — fluids which, by dis- 
solving any trace of oxide or by preventing oxidation, enable the 
tin more completely to alloy with the iron. Tin tacks are in reality 
tinned iron tacks : a tin nail would be too soft to drive into wood. 
Tin may be granulated by melting and triturating briskly in a hot 
mortar, by shaking melted tin in a box on the inner sides of which 
chalk has been rubbed, or in thin little bells or corrugated frag- 
ments (Granulated Tin, B. P.), by melting in a ladle and, immedi- 
ately it is fluid, pouring from the height of a few feet into water. 
Powdered tin has been used medicinally as a mechanical irritant to 
promote expulsion of worms. The hairs of the pod of kiwach (Hin- 
dustani) or cowhage (Mucuna pruriens) (P. I.) is almost the only 
other medicine (excluding diluents and dentifrices) which acts in 
such a directly mechanical manner. 

The chemical position of tin among the metals is close to that of 
arsenum and antimony. Its atom is quadrivalent, Sn ///7 , and 
bivalent, Sn 7/ . The two classes of salts are termed stannic and 
stannous respectively. 

Keactions having Synthetical Interest. 
Stannous Chloride, or Lower Chloride of Tin. 

First Synthetical Reaction. — Warm a fragment of tin with 
hydrochloric acid ; hydrogen escapes and solution of stannous 
chloride (SnCl 2 , perhaps Sn 2 Cl 4 ) is formed. It may be retained 
for future experiments. 

1 ounce of tin dissolved in 3 fluidounces of hydrochloric acid and 
1 of water, and the resulting solution diluted to 5 fluidounces, con- 
stitutes the ■' Solution of Stannous Chloride," B. P. 

Solid Stannous Chloride. — By evaporation of the above solution 
stannous chloride is .obtainable in crystals (SnCl 2 ,2H 2 0). It is a 
powerful reducing agent, even a dilute solution precipitating gold, 
silver, and mercury from their solutions, converting ferric and 
cupric into ferrous and cuprous salts, and partially deoxidizing 
arsenic, manganic, and chromic acids. It absorbs oxygen from the 
air, and is decomposed when added to a large quantity of water 
unless some acid be present. It is used as a mordant in dyeing and 
calico-printing. 

Stannic Chloride, or Perchloride of Tin. 

Second Synthetical Reaction. — Through a portion of the solu- 
tion of the stannous chloride of the previous reaction pass chlo- 
rine gas ; solution of stannic chloride (SnCl 4 ) is formed. Or 






tin. 243 

add hydrochloric acid to the stannous solution, boil, and in a 
fume-chamber slowly drop in nitric acid until no more fumes 
are evolved ; again stannic chloride results. Reserve the solu- 
tions for subsequent experiments. 

Stannic Oxide, or Anhydride and Stannates. 

Third Synthetical Reaction — Boil a fragment of tin with 
nitric acid, evaporate to dryness, and strongly calcine the resi- 
due ; light buff-tinted stannic anhydride (Sn0 2 ) is produced. 
Heat the stannic anhydride with excess of solid caustic potash 
or soda ; stannate of the alkali-metal (K 2 Sn0 3 or Na 2 Sn0 3 ) 
results. Dissolve the stannate in water and add hydrochloric 
acid ; white gelatinous stannic acid (H 2 Sn0 3 ) is precipitated. 
Stannic acid is also obtained on adding an alkali to solution of 
stannic chloride ; it is soluble in excess of acid or alkali. 

The product of the action of nitric acid on tin is also an acid, but 
from its insolubility in hydrochloric and other acids is different 
from ordinary stannic acid. It is termed metastannic acid (from 
fiera, meta, beyond), and its molecule probably has a composition 
expressed by the formula H 10 Sn 5 O ]5 (vide Index, " Isomerism"). It 
is also produced on gently heating stannic acid : 

5H>0 3 = H 10 Sn 5 O 15 

Stannic acid. Metastannic acid. 

Metastannates have the general formula M / 2 H 8 Sn 5 15 . 

Both acids yield buff-colored stannic oxide or anhydride (Sn0 2 ) 
when strongly heated. The latter is employed in polishing plate 
under the name of putty powder. Sodium stannate (Na 2 Sn0 3 ,4H 2 0) 
is used as a mordant by dyers and calico-printers under the name 
of tin prepare-liquor. 

Reactions having Analytical Interest (Tests). 

Stannous or Stannic Salts. — Heat any solid compound of tin 
with a mixture of potassium cyanide and sodium carbonate on 
charcoal by the inner flame of the blowpipe. Hard globules 
of tin separate, having, when cut by a knife, characteristic 
brightness and whiteness. 

Stannous Salts. 

First Analytical Reaction. — Through a diluted solution of 
a stannous salt (stannous chloride, for example) pass sulphur- 
etted hydrogen gas ; a brown precipitate (stannous sulphide, 
SnS) results. Pour off the supernatant liquid, add ammonia 
to the moist precipitate (to neutralize acid), and, lastly, yellow 
ammonium sulphydrate solution ; the precipitate is dissolved. 



244 THE METALLIC RADICALS. 

Aqueous solution of ammonium sulphydrate becomes yellow when 
a day or two old, and then contains excess of sulphur, some of that 
element having become displaced by oxygen absorbed from the air ; 
hence in the above reaction the stannous sulphide (SnS), in dis- 
solving, becomes stannic sulphide (SnS 2 ); for the latter is precipi- 
tated on decomposing the alkaline liquid by an acid. 

Second Analytical Reaction. — To solution of a stannous salt 
add solution of potash or soda : a white precipitate falls (stan- 
nous hydrate, Sn2HO). Add excess of the alkali ; the pre- 
cipitate dissolves. Boil the solution ; some of the tin is 
reprecipitated (as blackish stannous oxide, SnO). Ammonia 
gives a similar white precipitate, insoluble in excess. The 
alkaline carbonates do the same, carbonic acid gas escaping. 

Stannic Salts. 

Third Analytical Reaction. — Through solution of a stannic 
salt (stannic chloride, for example) pass sulphuretted hydro- 
gen gas ; a yellow precipitate results (stannic sulphide, SnS 2 ). 
Pour off the supernatant liquid, and to the moist precipitate 
add ammonia (to neutralize acid), and then ammonium sulphy- 
drate ; the precipitate dissolves. 

Note. — In this reaction the presence of much hydrochloric acid 
must be avoided ; the formation of the precipitate is also facilitated 
if the solution be warmed. Stannic sulphide, like arsenum and 
antimony sulphides, dissolves in a solution of alkaline sulphide or 
sulphydrate, with formation of definite crystallizable sulphostan- 
nates' (M^SnSg). 

Anhydrous stannic sulphide, prepared by sublimation, has a yellow 
or orange lustrous appearance, and is known as mosaic gold. It was 
formerly used by decorators as bronzing-powder, but the latter is now 
commonly powdered bronze-leaf. 

Fourth Analytical Reaction. — To solution of a stannic salt 
add potash or soda ; a white precipitate appears (stannic acid, 
H 2 Sn0 3 ). Add excess of the alkali ; the precipitate dissolves. 
Boil the mixture ; no reprecipitation occurs — a fact enabling 
stannic to be distinguished from stannous salts. 

Ammonia gives a similar precipitate slowly soluble in excess. 
The fixed alkali-metal carbonates do the same, carbonic acid gas 
escaping ; after a time the stannic salt is again deposited, probably 
as stannate of the alkali-metal. Ammonium carbonate and all the 
bicarbonates give a precipitate of stannic acid insoluble in excess. 

Antidotes. — In cases of poisoning by tin salts (dyers' tin-liquor, 
e.g.) solution of ammonium carbonate should be given, and white 
of egg is also said to form an insoluble precipitate. Vomiting 
should be induced, and the stomach-pump or stomach-siphon applied. 



GOLD. 245 

GOLD. 

Symbol, Au. Atomic weight, 196.85. 

Source. — Gold occurs in the free state in nature, occasionally in 
nodules or nuggets, but commonly in a finer state of division termed 
gold-dust. 

Preparation. — Gold is separated from sand, crushed quartz, or 
other earthy matter with which it may be associated by agitation 
with water, when the gold, from its relatively greater specific grav- 
ity, falls to the bottom of the vessel first, the lighter mineral matter 
running off with the water. From this rich sand the gold is dis- 
solved out by mercury, the amalgam filtered and afterward distilled, 
when the mercury volatilizes and gold remains. The amalgamation 
may be facilitated by the use of sodium, as already described in 
treating of silver. From even the poorest ores gold may be dis- 
solved by solution of potassium cyanide. (See Faraday on gold- 
leaf, 1857.) 4KCy + Au 2 + + H 2 = 2AuKCy 2 + 2KOH. 
Elkington deposited the metal by the aid of a battery, of which the 
anode or positive pole was a plate of gold, in 1840, deposition taking 
place at the cathode or negative pole (ava, ana, upward or onward ; 
Kara, kata, downward ; 6d*og, odos, way). The gold solution was 
made, as now, from the gold chloride and potassium cyanide, potas- 
sium chloride and auro-cyanide (AuKCy 2 ) being formed, but Elking- 
ton in 1857 made it direct from a gold anode with a small cathode 
in solution of potassium cyanide. 

Pure gold is too soft for general use as a circulating medium. 
Gold coin is an alloy of copper and gold, that of Great Britain con- 
taining 1 of the former to 11 of the latter, or 8^ per cent, of copper, 
that of France, Germany, and the United States about 10 per cent. 
Jewellers 1 gold varies in quality, every 24 parts containing 18, 15, 
12, or 9 parts of gold, the alloys being technically termed 18, 15, 
12, or 9 carat fine, the reckoning being in the old " parts per 24," 
instead of the more usual parts per cent. Articles made of the 
better qualities are usually stamped by authority. Trinkets of 
inferior intrinsic worth are commonly thinly coated with pure gold 
by electro-deposition or otherwise. The so-called mystery gold is. an 
alloy of about 1 part platinum and 2 parts copper with a little silver. 
It resists the action of strong nitric acid. The action of aqua regia 
and then ammonia reveals it cupric character. Gold-leaf is nearly 
pure gold passed between rollers till it is about -g^ of an inch in 
thickness, and then hammered between sheets of animal membrane, 
termed gold-beaters' skin, and calf-skin vellum, till it is -j&wooo or 
2W000 °f an i ncn in thickness. It may even be hammered till 
280,000 leaves would be required to form a pile an inch thick. 

Gold Coinage. — The weight of gold is expressed in- England 
in ounces troy and decimal parts of an ounce, and the metal is 
always taken to be of standard fineness (11 gold and 1 alloy) unless 
otherwise described. The degree of "fineness" of gold, as ascer- 
tained by assay, is expressed decimally, fine pure gold (" gold free 
from metallic impurities," B. P.) being taken as unity, or 1.000. 
Thus gold of British standard is said to be 0.9166 fine, of French 
standard 0.900 fine. The legal weight of the sovereign is 0.2568 



246 THE METALLIC RADICALS. 

ounce of standard gold, or 123.274 grains, the weight coming from 
1 pound of standard gold (5760 grains) being coined into 44J 
guineas. Gold coins are legal tender to any amount, provided 
that the weight of each sovereign does not fall below 122.5 grains, 
or in the case of a half-sovereign 61.125 grains; these are the 
"least current" weights of the coins. 

In the United States the weight of gold is expressed in ounces 
troy and decimal parts thereof. 900 parts of gold are alloyed with 
100 parts of copper. The weight of the eagle or ten-dollar gold 
piece is 258 grains and 900 fine. 

Note. — In analysis gold comes out among the sulphides of metals 
precipitated by sulphuretted hydrogen, and of those sulphides, it, 
like the sulphides of tin, antimony, and arsenum, is soluble in 
yellow ammonium sulphydrate solution. 

Quantivalence. — Gold is trivalent (Au 7// ) in the auri- or auric 
compounds, univalent (Au') in the auro- or aurous salts. 

Reactions. 

Synthetical Reaction. — Place a fragment of gold (e. g. gold- 
leaf) in 10 or 20 drops of aqua regia (a mixture of 3 parts of 
nitric and 4 or 5 of hydrochloric acid), and set aside in a warm 
place ; solution of gold perchloride or auric chloride (AuCl 3 ) re- 
sults. Evaporate nearly to dryness to remove most of the excess 
of acid, dilute with water, and retain the solution for subse- 
quent experiments. 60 grains of gold treated thus, and the 
resulting chloride dissolved in 5 ounces of distilled water con- 
stitutes " Solution of Perchloride of Gold," B. P. The salt itself 
is very deliquescent. A compound of gold and sodium chlorides, 
in molecular proportions, crystallizes readily and is more stable. 
Au 2 -j- 2HN0 3 + 6HC1 = 2AuCl 3 + 2NO + 4H 2 0. 

This reaction has analytical interest also, for in examining a sub- 
stance suspected to be or to contain metallic gold, solution would have 
to be effected in the above way before reagents could be applied. Gold 
is insoluble in hydrochloric, nitric, and the weaker acids. 

Gold and Sodium Chloride {Auri et Sodii Chloridum, U. S. P.) 
is " a mixture of equal parts, by weight, of dry auric chloride and 
sodium chloride." 

Analytical Reactions (Tests). 

First Analytical Reaction, — Through a few drops of solution 
of an auric salt (the chloride, AuCl 3 , is the only convenient 
one) pass sulphuretted hydrogen ; a brown precipitate results 
(auric sulphide, Au 2 S 3 ). Filter, wash, and add yellow ammo- 
nium sulphydrate solution ; the precipitate dissolves. 

Second Analytical Reaction. — To solution of a salt of gold 
add a ferrous salt and set the tube aside ; metallic gold, having 
its characteristic lustrous appearance, is precipitated, a ferric 



PLATINUM. 247 

salt remaining in solution. Oxalic acid also and most free 
metals precipitate the gold. 

This is a convenient way of preparing pure gold — or fine gold, as 
it is termed — or of working up the gold residues of laboratory 
operations. The precipitate, after boiling with hydrochloric acid, 
washing and drying, may be obtained in a button by mixing with 
an equal weight of borax or acid potassium sulphate and fusing in 
a good furnace. 

Third Analytical Reaction. — Add a few drops of dilute solu- 
tions of stannous and stannic chloride to a considerable quan- 
tity of distilled water ; pour the liquid, a small quantity at a 
time, into a very dilute solution of auric chloride (AuCl 3 ), well 
stirring ; the mixture assumes a purple tint, and flocks of a 
precipitate known as the Purple of Cassius (from the name of 
the discoverer, M. Cassius) are produced. 

The same compound is formed on immersing a piece of tin-foil in 
solution of auric chloride ; it is said to be a mixture of auric, aurous, 
stannic, and stannous oxides. It is the coloring agent in the finer 
varieties of ruby glass. 

PLATINUM. 

Symbol, Pt. Atomic weight, 194.4. 

Source. — Platinum, like gold, occurs in nature in the free state, 
the chief sources of supply being Mexico, Brazil, and Siberia. It is 
separated from the soil by washing. 

Uses. — The chief use of platinum is in the construction of foil, 
wire, crucibles, spatulas, capsules, evaporating-dishes, and stills for 
the use of the chemical analyst or manufacturer. It is tolerably 
hard, fusible with very great difficulty, not dissolved by hydro- 
chloric, nitric, or sulphuric acid, and only slightly affected by alka- 
line substances. It is attacked by aqua regia, with production of 
platinum perchloride or platinic chloride (PtCl 4 ,5II 2 0). It forms 
fusible alloys with lead and other metals, and with phosphorus a 
phosphide which easily melts. Neither of these substances, there- 
fore, nor mixtures which may yield them, should be heated in 
platinum vessels. Hammered or chased, not drawn, vessels are the 
most durable. They are best cleaned by aid of a little fine water- 
worn (not " sharp ") sea-sand. They should not be very suddenly 
heated or very suddenly cooled. They should only be heated by 
the outer portions of flames, exposure to strongly heated carbon- 
iferous or siliconiferous surfaces being avoided, for at high tempera- 
tures platinum has a tendency to unite Avith carbon or silicon. 

The chemical position of platinum among the elements is close to 
that of gold. Its atom is quadrivalent (Pt ///7 ) in some compounds, 
in others apparently bivalent (Pt // ). The higher salts are termed 
platinic, the lower platinous. 

The specific gravity of platinum is 21.5, and that of iridium, an 
allied metal, 22.4. 



248 THE METALLIC RADICALS. 

Reactions. 

Platinic Chloride, or Platinum Perchloride. 

Synthetical Reaction. — Place a fragment of platinum in a 
little aqua regia and set the vessel aside in a warm place, adding 
more acid from time to time if necessary ; solution of platinum 
perchloride (PtCl 4 ) results. Evaporate the solution to reniove 
excess of acid, and complete the desiccation over a water-bath. 
Dissolve the residue in water, and retain the solution for sub- 
sequent experiments and as a reagent for the precipitation of 
salts either of potassium or ammonium. 1 part of platinum 
treated in the above manner, and the resulting chloride dis- 
solved in 20 parts of water, constitutes " Solution of Perchlo- 
ride of Platinum," B. P. and U. S. P., or 1.7 grms. of pure 
platinic chloride (PtCl 4 ,5H 2 0) dissolved in 20 cc. of distilled 
water gives " Platinic Chloride Test-solution," U. S. P. 

This reaction has analytical interest, for, in testing a sub- 
stance suspected to contain metallic platinum, solution would 
have to be thus effected before reagents could be applied. 

Analytical Reactions (Tests). 

First Analytical Reaction. — Through a few drops of a solu- 
tion of a platinic salt (PtCl 4 is the only convenient one), to 
which an equal quantity of solution of sodium chloride has 
been added, pass sulphuretted hydrogen ; a dark-brown precip- 
itate results (platinic sulphide, PtS 2 ). Filter, wash, and add 
ammonium sulphydrate ; the precipitate dissolves. 

If sodium chloride be not present in the above reaction, the pre- 
cipitated sulphide will contain platinous chloride, and may detonate 
if heated. 

Second Analytical Reaction. — Add excess of sodium car- 
bonate and some sugar to solution of platinum perchloride, and 
boil ; a black precipitate (metallic platinum) falls. 

Platinum black (B. P.) is the name of this precipitate. It pos- 
sesses in a high degree a quality common to many substances, but 
largely possessed by platinum — namely, that of absorbing or occlud- 
ing gases. In its ordinary state, after well washing and drying, it 
absorbs from the air and retains many times its bulk of oxygen. A 
drop of ether or alcohol placed on it is rapidly oxidized, the platinum 
becoming hot. This action may be prettily shown by pouring a 
few drops of ether into a beaker (one having portions of the top and 
sides broken off answers best), loosely covering the vessel with a 
card, and suspending within the beaker a platinum wire, one end 
being attached to the card by passing through its centre, the other 
terminating in a short coil or helix near the surface of the ether : on 



CADMIUM. 249 

now warming the helix in a flame and then rapidly introducing it 
into the beaker, it will become red hot and continue to glow. In this 
experiment partial combustion goes on between the ether vapor and 
the concentrated oxygen of the air, the products of the oxidation 
revealing themselves by their odor. 

Third Analytical Reaction. — To solution of platinum per- 
chloride add solution of ammonium chloride ; a yellow gran- 
ular -precipitate (the double chloride, PtCl 4 ,2NH 4 Cl) falls. 
When slowly formed in dilute solutions the precipitate is 
obtained in minute orange prisms. 

Potassium chloride (KC1) gives -a similar precipitate (PtCl 4 ,2KCl). 
Platinic chloride having been stated to be a test for potassium and 
ammonium salts, the reader is prepared to find that potassium and 
ammonium salts are tests for platinic salts. The double sodium 
compound (PtCl 4 ,2NaCl) is soluble in water. 

Collect the precipitate, dry, and heat in a small crucible ; it 
is decomposed, and metal in a finely-divided gray state (spongy 
platinum) remains. 

3(PtCl 4 ,2NH 4 Cl) =Pt 3 + 2NH 4 C1 + 16HC1 + 2N 2 . 

Heat decomposes the salt of potassium into Pt-f-2KCl-f- Cl 4 , the 
chlorine escaping and the potassium chloride remaining with the 
platinum. 

In working up the platinum residues of laboratory operations the 
mixture should be dried, burnt, boiled successively with hydro- 
chloric acid, water, nitric acid, water, then dissolved in aqua regia, 
excess of acid removed by evaporation, ammonium chloride added, 
the precipitate washed with water, dried, ignited, and the resulting 
spongy platinum retained or converted into perchloride for use as a 
reagent for alkali-metals. It is by such processes that the native 
platinum is treated to free it from the rare metals palladium, rho- 
dium, osmium, ruthenium, and iridium. The spongy platinum is 
converted into the massive condition by a refinement on the black- 
smith's process of welding (German icellen, to join), or by fusing in 
a flame of pure oxygen and hydrogen gases — the oxyhydrogen 
blowpipe. 

Occlusion by Spongy Platinum. — Spongy platinum has great power 
of occlusion. A small piece held in a jet of hydrogen causes igni- 
tion of the gas, owing to the close approximation of particles of 
oxygen (from the air) and hydrogen. Dobereiner's lamp is con- 
structed on this principle, the apparatus being essentially a vessel 
in which hydrogen is generated by the action of diluted sulphuric 
acid on zinc, and a cage for holding the spongy platinum. 

CADMIUM. 

Symbol, Cd. Atomic weight, 112. 

In most of its chemical relations cadmium resembles zinc. In 
nature it occurs chiefly as an occasional constituent of the ore of that 
metal. In distilling zinc containing cadmium the latter, being the 



250 THE METALLIC RADICALS. 

more volatile, passes over first. In analytical operations cadmium, 
unlike zinc, comes down among the metals precipitated by sul- 
phuretted hydrogen ; that is, its sulphide is insoluble in diluted 
hydrochloric acid, while zinc sulphide is soluble. It is a white 
malleable metal, nearly as volatile as mercury. Sp. gr. 8.7. 

Beyond the occasional employment of the sulphide as a pigment 
(jaune brillant), and the iodide in photography, cadmium and its 
salts are but little used. The atom of cadmium is bivalent (Cd"). 

Reactions. 

Cadmium Iodide. 

First Synthetical Reaction. — Digest together, in a flask, 
metallic cadmium, warm water, and iodine until the color of 
the iodine disappears ; solution of cadmium iodide (Cdl 2 ) re- 
mains. Pearly micaceous crystals may be obtained on evap- 
orating the solution. 

This salt is employed with other iodides in iodizing collodion for 
photographic use. It readily melts, and is soluble in water or 
spirit, the solution reddening litmus. 

Cadmium Sulphate. 

Second Synthetical Reaction. — Dissolve cadmium in nitric 
acid ; pour the resulting solution of cadmium nitrate (Cd2N0 3 ) 
into a solution of sodium carbonate ; dissolve the precipitate 
of cadmium carbonate (CdC0 3 ) in dilute sulphuric acid, sepa- 
rate and crystallize. Cadmium sulphate (CdS0 4 ) is a white 
crystalline salt soluble in water. 

Analytical Reactions (Tests). 

First Analytical Reaction. — Through solution of a cadmium 
salt (Cdl 2 or CdCl 2 ) pass sulphuretted hydrogen ; a yellow 
precipitate (cadmium sulphide, CdS) falls, resembling in ap- 
pearance arsenous, arsenic, and stannic sulphides. Add ammo- 
nium sulphydrate ; the precipitate, unlike the sulphides just 
mentioned, does not dissolve. 

Cadmium and copper sulphides may be separated by solution of 
potassium cyanide, in which copper sulphide is soluble and cadmium 
sulphide insoluble. 

Second Analytical Reaction. — To a cadmium solution add 
solution of potash ; a white precipitate results (cadmium hy- 
drate, Cd2HO), insoluble in excess of the potash. 

Zinc hydrate (Zn2HO), precipitated under similar circumstances, 
is soluble in solution of potash ; the filtrate from the cadmium 
hydrate may therefore be tested for any zinc occurring as an impurity 
by applying the appropriate reagent — ammonium sulphydrate. 



BISMUTH. 251 

Before the blowpipe flame, on charcoal, cadmium salts give a 
brown deposit (cadmium oxide, CdO). 

BISMUTH. 

Symbol, Bi. Atomic weight, 208. 

Source. — Bismuth occurs in the metallic state in nature. It is 
freed from adherent quartz, etc. by simply heating, when the metal 
melts, runs off, and is collected in appropriate vessels (Bismuthum, 
B. P.). It is also met with in combination with other elements. 
Bismuth is grayish-white, with a distinct pinkish tinge. 

Purification. — Arsenum may be removed from melted bismuth 
by a rod of iron, iron arsenide rising to the surface of the mass : 
antimony, by stirring in some bismuth oxide, when antimony oxide 
separates. Other metals in bismuth, especially copper, are con- 
verted into sulphides, while bismuth is not affected, on fusing the 
crude metal with about 5 per cent, of potassium cyanide and 2 per 
cent, of sulphur, the whole being well stirred for a quarter of an 
hour with a clay rod (stem of a tobacco-pipe). On pouring off the 
metal from the flux, and melting and stirring it with about 5 per 
cent, of a mixture of potassium and sodium carbonates, sulphur and 
traces of other impurities are removed, and the metal is obtained 
pure (Bismuthum Puriflcatum, B. P.). — Tamm. 

Uses. — Beyond the employment of some of its compounds in 
medicine bismuth is but little used. Melted bismuth expands con- 
siderably on solidifying, and hence is valuable in taking sharp im- 
pressions of dies. It is a constituent of some kinds of type-metal 
and of pewter solder. 

The position of bismuth among the metals is close to that of arsenum 
and antimony. Its atom is trivalent (Bi /// ) and rarely quinquiv- 
alent (Bi v ). 

Reactions having Synthetical Interest. 

Bismuth Nitrate, or Nitrate of Bismuth. 

First Synthetical Reaction. — To a few drops of nitric acid 
and an equal quantity of water, in a test-tube, add a little 
powdered bismuth, heating the mixture if necessary ; nitric oxide 
(NO) escapes, and solution of bismuth nitrate (Bi3N0 3 ) results. 

Bi 2 + 8HN0 3 = 2(Bi3N0 3 ) + 2NO + 4H,0 

Bismuth. Niiric acid. Bismuth nitrate. Nitric oxide. Water. 

The solution evaporated gives crystals (Bi3N0 3 ,5H 2 0), any arse- 
num which the bismuth might contain remaining in the mother- 
liquor. 

To make bismuth nitrate and other salts on a larger scale, 2 
ounces of the metal, in small fragments, are gradually added to a 
mixture of 4 fluidounces of nitric acid and 3 of water, and when 
effervescence (due to escape of nitric oxide) has ceased the mixture 
is heated for ten minutes, poured off from any insoluble matter, 
evaporated to 2 fluidounces to remove excess of acid, and then either 



252 THE METALLIC RADICALS. 

set aside for crystals to form, or poured into half a gallon of water 
to form bismuth oxynitrate, or into a solution of 6 ounces of ammo- 
nium carbonate in a quart of water to form the oxycarbonate, as 
described in the following reactions. 

The precipitates should be washed with cold water, and dried at a 
temperature not exceeding 150° F. Exposed in the moist state to 
212° F. (100° C.) for any length of time, they undergo slight decom- 
position. 

Bismuth Subnitrate or Oxynitrate. 

Second Synthetical Reaction. — Pour some of the above solu- 
tion of nitrate into a considerable quantity of water ; decom- 
position occurs, and bismuth oxynitrate (BiON0 3 ) in a hydrous 
state (BiON0 3 ,H 2 0) (Bismuthi Subnitras, Subnitrate of Bis- 
muth, or Bismuth Subnitrate, U. S. P.), is precipitated : 

Bi3N0 3 + H 2 =• BiON0 3 + 2HN0 3 

Bismuth nitrate. Water. Bismuth oxynitrate. Nitric acid. 

Filter, and test the filtrate for bismuth by adding excess of 
sodium carbonate ; a precipitate shows that some bismuth re- 
mains in solution. The following equation, therefore, probably 
more nearty represents the decomposition : 

5(Bi3N0 3 ) + 8H 2 = 4(BiON0 3 ,H 2 0) + Bi 3 N0 3 ; 8HN0 3 

Bismuth nitrate. Water. Bismuth oxynitrate. Bismuth nitrate in acid. 

Decomposition of bismuth nitrate by water is the process of the 
Pharmacopoeia for the preparation of bismuth oxynitrate or " sub- 
nitrate" for use in medicine. For this purpose the original metal 
must contain no arsenum. In manufacturing the compound, there- 
fore, before pouring the solution of nitrate into water the liquid 
should be tested for arsenum by one of the hydrogen tests ; if that 
element be present, the solution must be evaporated, and only the 
deposited crystals be used in the preparation of the oxynitrate. For 
on pouring an arsenical solution of bismuth nitrate into water the 
arsenum is not wholly removed in the supernatant liquid, unless the 
oxynitrate be redissolved and reprecipitated several times, according 
to the amount of arsenum present. 

Bismuth subnitrate is gradually decomposed by solution of alka- 
line carbonates ; also by the bicarbonates, with production of carbonic 
acid gas, bismuth oxycarbonate and nitrate of the alkali-metal being 
formed. It is sometimes administered in the form of a lozenge 
(Trochisci Bismuthi, B. P.). 

Oxysalts of Bismuth. — It will be noticed that the formula for 
bismuth subnitrate (BiN0 4 ) does not accord with that of other 
nitrates, the characteristic elements of which are N0 3 . Analogy 
would seem to indicate, however, that the fourth atom of oxygen has 
different functions to the three in the N0 3 ; for on pouring solution 
of bismuth chloride (BiCl 3 ) into water, oxychloride is produced 
(BiOCl) (a white powder used as a cosmetic, " pearl-white" (Blanc 
de Perle), also in enamels and in some varieties of sealing-wax). The 



BISMUTH. 253 

bromide (BiBr 3 ) and iodide (Bil 3 ), similarly treated, yield oxybro- 
mide (BiOBr) and oxyiodide (BiOI). The subnitrate (BiN0 4 ) is 
therefore probably an analogous compound, an oxynitrate (BiON0 3 ). 
The sulphate (Bi 2 3S0 4 ) also decomposes when placed in water, 
giving what may be termed an oxysulphate, the formula of which 
is Bi 2 2 S0 4 . 

It is difficult to prove whether or not the water in the " sub- 
nitrate " or hydrous bismuth oxynitrate (BiON0 3 ,H 2 0) is an integral 
part of the salt. If it is, the compound is simply bismuth hydrato- 
nitrate (BiN0 3 2HO). 

Bismuth Oxide. 

Third Synthetical Reaction. — Boil bismuth subnitrate with 
solution of soda for a few minutes ; it is converted into yellowish 
bismuth oxide (Bi 2 3 ) (Bismuthi Oxidum, B. P.). 

2BiON0 3 + 2NaHO = Bi 2 3 + 2NaN0 3 + H 2 

Bismuth Sodium Bismuth Sodium Water, 

oxynitrate. hydrate. oxide. nitrate. 

Bismuth Subcarbonate or Oxy carbonate. 

Fourth Synthetical Reaction. — To solution of bismuth nitrate 
add solution of ammonium carbonate ; a white precipitate of 
hydrous oxycarbonate (2Bi 2 2 C0 3 ,H 2 0) (JBismuthi Subcarbonas, 
or Bismuth Subcarbonate, U. S. P.) falls. 

2(Bi3N0 3 )-f-2N 3 H n C 2 5 +H 2 = 6NH 4 N0 3 + Bi 2 2 C0 3 + 3C0 2 

Bismuth Ammonium Ammonium Bismuth Carbonic 

nitrate. "carbonate." nitrate. oxycarbonate. acid gas. 

This compound may be regarded as similar in constitution to the 
oxysalts just described. In Bi 2 C0 5 one scarcely recognizes the 
characteristic elements of carbonates, but, considering the prepara- 
tion to be an oxycarbonate (Bi 2 2 C0 3 ), its relations to carbonates 
and oxides are evident. These subsalts may all be viewed as normal 
bismuth salts in one molecule of which an atom of oxygen displaces 
an equivalent proportion of other acidulous atoms or radicals : 

Chloride Bi3Cl Oxychloride . . BiOCl 

Bromide Bi3Br Oxybromide . . BiOBr 

Iodide Bi3I Oxyiodide . . . BiOI 

Nitrate Bi3N0 3 Oxynitrate . . BiON0 3 

Sulphate Bi 2 3S0 4 Oxysulphate . Bi 2 2 S0 4 

Carbonate (unknown) . Bi 2 3C0 3 Oxycarbonate . Bi 2 2 C0 3 

They may be viewed, in short as salts in process of conversion to 
oxide ; continue the substitution further, and each yields bismuth 
oxide (Bi 2 3 ). They are 'also regarded as salts of a hypothetical 
radical bismuthyl (BiO). 

Bismuth Citrate, or Citrate of Bismuth. 

Fifth Synthetical Reaction. — Heat 10 parts of bismuth oxy- 
nitrate, 7 of citric acid crystals, and 30 to 40 of water together 
12 



254 



THE METALLIC RADICALS. 



for a few minutes, until a drop of the mixture forms a clear 
solution with ammonia-water. Dilute the crystalline mass with 
eight to ten times its volume of water, and set aside for a short 
time to let the citrate deposit ; decant the clear liquid. Wash 
the crystalline sediment three or four times in a similar man- 
ner, drain and dry, either on a water-bath or by mere exposure. 
The yield is 13| parts, showing that the salt is anhydrous and 
that its formula is BiC 6 H 5 7 (Rother). This is the Bismuthi 
Citras, U. S. P. 

Sixth Synthetical Reaction. — To bismuth citrate, rubbed to 
a paste with a very little water, add sufficient solution of 
ammonia to dissolve the citrate. The product, when of a 
strength of 800 grains of citrate in a pint, is the official Solu- 
tion of Citrate of Bismuth and Ammonium (Liquor Bismuthi 
et Ammonii Citratis, B. P.), shortly termed Liquor Bismuthi. 
This solution, evaporated to the consistence of syrup, spread 
on glass and dried at 100° F., yields scales of the solid salt (Bis- 
muthi et Ammonii Citras, U. S. P.). In constitution it is pos- 
sibly ordinary ammonium citrate, in which three atoms of 
hydrogen are displaced by one of bismuth. (For similar salts 
see p. 156.) 

fH 3 

Us J 

Hydrogen-ammonium citrate. 



Bij 

Bismuth-ammonium citrate. 



Reactions having Analytical Interest (Tests). 

First Analytical Reaction. — Through solution of a bismuth 
salt (a slightly acid solution of nitrate, for example) pass sul- 
phuretted hydrogen ; a black precipitate (bismuth sulphide, 
Bi 2 S 3 ) falls. Add ammonia (to neutralize acid), and then ammo- 
nium sulphydrate ; the precipitate, unlike As 2 S 3 and Sb 2 S 3 , is 
insoluble. 

Second Analytical Reaction. — Concentrate almost any acid 
solution of a bismuth salt and pour into much water (contain- 
ing sodium chloride) ; a white precipitate results. 

This reaction is characteristic of bismuth salts : it has already 
been amply explained. The oxychloride is specially insoluble, and 
is distinguished from that of antimony by being insoluble in solu- 
tion of tartaric acid. 

Third Analytical Reaction. — To a solution of bismuth salt 
add an alkali ; a white precipitate results (bismuth hydrate, 
Bi3HO), insoluble in excess and becoming yellowish on boiling. 



BISMUTH. 255 

Fourth Analytical Reaction. — A small quantity of the fol- 
lowing reagent, including both supernatant liquid and precip- 
itated yellow scales, is transferred to a test-tube, and gradually 
heated till solution takes place. Any liquid containing, or sup- 
posed to contain, bismuth is then added, and the whole allowed 
to cool. The separated scales will show a distinct change in 
color from the original yellow to dark orange or crimson, accord- 
ing to the quantity of bismuth present. 

The reagent may be prepared by adding to a boiling solution 
of lead acetate, containing about § grain to the ounce, a few 
drops of acetic acid and solution of potassium iodide in con- 
siderable excess. On cooling, lead iodide is deposited in the 
characteristic yellow crystalline plates or scales. 

Test for Calcium Phosphate in Bismuth Salts. — Dissolve the 
powder in nitric acid, add about twice its weight of citric acid 
and sufficient ammonia to give decided alkalinity ; then boil, 
keeping the mixture faintly alkaline with ammonia : bismuth 
remains in solution and calcium phosphate is precipitated. 

Official (B. P.) Tests for Other Impurities in Bismuth or its 
Salts. — Dissolve in nitric acid ; concentrate and set aside for 
crystals of bismuth nitrate to form ; pour off the mother-liquor, 
which will contain any impurities in a concentrated form. If 
this mother-liquor be evaporated with hydrochloric acid until 
all the nitric acid is dissipated, a little of the product yields no 
evidence of arsenum on being examined by the hydrogen test, 
commonly known as Marsh's test ; no blue coloration on adding 
water and excess of ammonia (copper), and no precipitate on 
filtering and saturating the ammoniacal filtrate with nitric acid 
(silver) ; no white precipitate with diluted sulphuric acid (lead) ; 
no red or black precipitate with sodium sulphite (tellurium or 
selenium) ; and no blue precipitate with potassium ferrocya- 
nide (iron). 



THE READER IS AGAIN ADVISED TO TRACE OUT THE EXACT 
NATURE OF EACH OF THE FOREGOING REACTIONS, CHIEFLY BY 
AID OF EQUATIONS OR DIAGRAMS. 



QUESTIONS AND EXEECISES. 



Enumerate the fifteen metals salts of which are frequently employed 
in pharmacy. — Mention the twelve rare metals interesting to pharma- 
cists. — Name the sources and official compounds of lithium. — Explain 
the formation of lithium citrate. — What is the strength of Liquor Lithise 
Effervescens ? — On what chemical hypothesis are lithium compounds 
administered to gouty patients? — Describe the relation of lithium to 



256 THE METALLIC RADICALS. 

other metals. — What is the chief test for lithium ? — Write a paragraph 
on strontium, its natural compounds, chemical relations, technical appli- 
cations, and tests. — What are the formula and properties of cerium 
oxalate? — Name the commonest ore of manganese and give an equation 
descriptive of its reaction with hydrochloric acid. — Explain the forma- 
tion of potassium permanganate, employing diagrams or equations. — 
How do the potassium manganates act as disinfectants? — What are the 
chief tests for manganese? — What are the chief uses of the compounds 
of cobalt?— How is cobalt analytically distinguished from nickel? — 
Mention applications of nickel in the arts. — What is the general color 
of nickel salts? — State the method of preparation of red potassium 
chromate. — Give the formulae of red and yellow potassium chromates. — 
How is red potassium chromate obtained ? — Describe the action of sul- 
phuretted hydrogen on acidified solutions of chromates. — What is the 
formula of chrome alum ? — Mention the chief tests for the chromic 
radical and for chromium. — How would you detect iron, chromium, and 
aluminium in a solution? — Define tin-stone, stream-tin, block-tin, grain-tin, 
tin plate. — Describe the position occupied by tin in relation to other 
metals. — What is the difference between stannic acid and rnetastannic 
acid? — State the applications of tin in the arts. — Mention the chief tests 
for stannous and stannic salts. — Name the best antidote in cases of 
poisoning by tin solutions. — How is gold-dust separated from the earthy 
matter with which it is naturally associated? — How much pure gold do 
English coin and jewellers' gold contain ?— State the average thickness 
of gold-leaf. — What is the weight of a sovereign ? — Explain the term 
"fineness" as applied to gold. What effect is produced on gold by 
hydrochloric, nitric, and nitrohydrochloric acids, respectively ? — By what 
reagents may metallic gold be precipitated from solution? — How is 
" purple of Cassius " prepared ? — Whence is platinum obtained ? — Why 
are platinum utensils peculiarly adapted for use in chemical laboratories? 
—How is platinum perchloride prepared? — Name the chief tests for 
platinum.— What is "platinum black"? — Describe an experiment demon- 
strative of the large amount of attraction for gases possessed by metallic 
platinum. — How is "spongy platinum" produced? — By what process 
may platinum be recovered from residues ? — What is occlusion in Chem- 
istry ? — In what condition does cadmium occur in nature? — By what pro- 
cess may cadmium iodide be prepared? — Mention the chief test for 
cadmium. — Distinguish cadmium sulphide from sulphides of similar 
color. — How is cadmium separated from zinc ? — How does bismuth occur 
in nature? — What is the quantivalence of bismuth? — Write down equa- 
tions descriptive of the action of nitric acid on bismuth, and water on 
bismuth nitrate. — How may arsenum be excluded from bismuth salts? 
— Give a diagram of the official process for bismuth carbonate.— Write 
formulae showing the accordance in molecular constitution of the official 
subnitrate and carbonate with the other salts of bismuth, and with 
ordinary nitrates and carbonates, — How is Liquor Bismuthi et Ammonii 
Citratis prepared? — Mention the tests for bismuth. 



The Analytical Classification of Metals. 
Practical Analysis. 

Bismuth is the last of the metals whose synthetical or analytical 
relations are of general interest. The position of the rarer among 
the common metals, and the influence which either has on the other 
during the manipulations of analysis, will now be considered. 
These objects will be best accomplished, and a more intimate 



ANALYTICAL TABLES. 



257 






§cd 



t>^W 



b.-BbjS-.sTwIm'S: 

& 2 P £> Si *^ h 



3 CD 
rh- CD 

IP'S' 



•Cf P 



1 ^ o 



'CD CL 



§g£ 
' p 

■< i — i CD 

£' p °° 



-•O-Cfq P P- 



Q 
& 



> O O" 1 <*- CT 
• P CC~- -I 

r^Z 3 JT 3 £T 



black. 



3 CfQ CD 
o 










cs: 

^ — v ~^™ OS ^^ ^ 3 2 

t_i FT CD ^ OlS" 

si S*2 E Oo2. 



pr 1 rt 



3 3 



M. CD 



PT5 


Precipitate 
Ba Sr Ca. 
Collect, wash, dis- 
solve in HC 2 H 3 2 , 
add K 2 Cr0 4 . 


h- 1 


1 * 

P O^ 


■El"-* 



sc? 



Cfq 



hj CD 

ffi CD 



CD SE C p rt" ^^ 



2 s 



o 



O CD 
3^" 



Si* 

wl'3 

►> CD « 
P-, CD 



" CD 



P 



o 

p 



"go 

d 

P 

er 



H3 

^ i— i Co 



52; « 



p- 



P- 



p] 



S3 

fa « 

S s 

oo 
O 

•=51 hcj 

O 

O » 

»3 

O H 

■SE; 

g CO 

>► 12! 

&3 O 

D3 CO 



^ S 
h in 

w S 
8> 

2 O 



H 03 

?3 O 

o a 



258 



TITE METALLIC RADICALS. 



acquaintance with all the metals be obtained, by analyzing, or 
studying the methods of analyzing, solutions containing one or more 
metallic salts. 

Of the foregoing tables, the first includes directions for the analy- 
sis of an aqueous or only slightly acid solution containing but one 
salt of any of the metals hitherto considered. Here the color of the 
precipitate or precipitates afforded by a metal under given circum- 
stances must largely be relied on in attempting the detection of the 
various elements. 

The long table is intended as a chart for the analysis of solutions 
containing salts of more than one of the common and rarer metals. 
It is a compilation from the foregoing reactions — an extension of 
the scheme for the analysis of salts of the ordinary metals. It often 
may be altered or varied in arrangement to suit the requirements 
of the analyst, 



OUTL1NK OF THE ANNEX KD ANALYTICAL TABLES. 



IICl 


H 2 S 


NIIJIS 


(NII 4 ) a C0 3 


(NH 4 ) 2 
HAs0 4 




Hg 


Cd ' 




Zn 


.2 


Ba 


Mg 


K 


(as mercu- 








® 








rous salt) 


Cu 


CQ 


Mn* 


3 . 

SO 












b 




,1^ 


Sr 




Na 


Pb 


Hg 


b 


Co 


SB 
■slz; 








(partially) 


(as mercuric 
















salt) 


2 


Ni 


B 


Ca 




NH 4 


Ag 


Ph 

(entirely) 


"3 












Bi 


h- 1 


Al 


"o . 

so 










As ] 




FTo 


£B 






L 




(as arseuous 




r e 








or arsenic 






g(Zj 










salt) 






? 










Sb 


03 


Cr 


B 










Sn 


B 












(as stan- 


a 












nous or 


V 












stannic 


x> 












salt) 


'o 












Au 


02 












Pt 













iVote. — The laboratory student should practice the examination of 
aqueous solutions of salts of the above metals until he is able to analyze 
with facility and accuracy. 



See p. 234. 



[ To face page 258. 
OR ONLY SLIGHTLY ACID SOLUTION OF ORDINARY 



3r Mg Li K Na NH 4 . 



Filtrate 
Cr Ba Ca Sr Mg Li K Na NH. 
}, NH 4 HS, warm gently and filter. 



HNO, 



Filtrate 
Ba Ca Sr Mg Li K Na NH, 

Add (NH 4 ) 2 C0 3 , warm, filter. 



si. 

pass H 2 S, 



ate 
Ni. 

ind a little 
HO, filter. 



eipitate 
O Ni. 
ve in HC1, 
>roceed as 
?d on page 
237. 



Precipitate 

Ba Sr Ca. 

Collect, wash, dissolve in 

HC 2 H 3 0,, add excess of 

K 2 Cr0 4 , filter. 



Filtrate 

Mg Li K Na NH 4 . 

Add (NH 4 )„HAs<> 4 , stir, filter 



Z: 

Yellow. 



Filtrate Ppt. Filtrate 

Sr Ca. Mg. Li K Na NH 4 

Add dilute H 9 S0 4 , White Evaporate to small 

let stand, filter. bulk. Add NH.HO. 



Ppt. Filt. 

Sr. | Ca. 

White Add 

lNH 4 HOand 

CNII 4 ) 2 C 2 4 . 



White ppL 



I Ppt. Filtrate 

| Li. K Na NH,. ! 
j See . Evaporate, 
p. - 2(32.! ignite, dissolve. 
K by PtCi 4 , 
Na by flame. 
NH, in original 
solution. 



See also p. 



T\fttX OK SHORT DIRECTIONS FOR APPLYING SOME OV 

SALTS 
Add hydrochloric acid. 



; FOREGOING ANALYTICAL REACTIONS TO THE ANALYSIS OF AN AQUEOI 
ANY OF THE COMMON OR RARER METALS OP GENERAL INTEREST. 



[To face page 258. 
.IUHII.Y ACID SOLUTION OF ORDINARY 



rreetpiutc 

. ! I) Ag. 



pwaptole 1 »«r»te 

- V".,*. Addu'-v 
s-jsj.,**'- . \M liu .ppt. 



Hg(ic) Ph 1H As(ous)(lo) Slj Sn(ous)(ii 



i lltrate 

Zn Mn <„ Ni Al Fe(ous i Ba Ca -r Mg l.i K Na NH,. 

,S through ill" liquid, filter. 



Precipitate 
i Hgtic) Pb I'.i \> sb 
i. wash, digest in Nil, us, fi 



Filtrate 
.1,, Co Ni Al Fe I r Ba l a 5r Mg l.i K Na Nil, 
Add Nll,< i, NH.ii'i, Ntl.H-, warm gently and filter. 



31. Add HN" 
M«ct. White ppt. 



•As si, Sn. 

Add dilute lit I, titter, drain well, add strong 

IK 1. boil, dilute slightly, filter. 



Black. 
Confirm 

l.y Cu 

test in 

original 

solu- 



Add Nil, 11(1. tiller. 



Y,ll.,«. 
Confirm 

bj ll.ii- 



Filtrato 

Sn SI,. 
Pour into H-apparat 



Precipitate 
Zn Mn Co Ni 11 Fe 'i 

sll, dissolve ill 111 1 Willi :i few drop, .,1 . IN" , 

I ,add Nil, lie, stir, lilti I 



Precipitate Filtrate 

Fe Al Cr. Zn Mn Co Ni. 

Wash, drv, lux- on l,,il will. \. i.litv will. Hi .11 ; n. pa- I 
Na,,C", and KNO,, boil in filter. 



l iltrate 

Ba ia ~ r Mg r.i K Na NH, 

Add Nil,-/",, warm, filter. 



Precipitate 

I'l. Hi. 

Wash, add a fe 

drops UNO,. 

dilute, filter. 



White Kitu 



» 



lilt. 

Cu. 

Acidify 

with 

1H ,ll,'i. 

Brown 

ppt. 



*■ 



remains on Zn. 
Dissolve in lit I 
and apply tests. 



and I'l are -peeialli -ought when 



rest 

original 

solution 



f yellow, ' r pre- 

31 in l'i\ ide in 

two parts. 


Mn. 
Add 

Nil, II" 

and 
Ml, IIS. 


Boil « 

II NH, 






Sol Sol. 
Al. Cr. 
Add Add 
11, CI IICIl,".. 
and and excess 
Minn, of AgN0 3 ; 


Pink, 
turning 
brow ii 

Search 


Fill. 
Zn. 
Add 
Nil, ll~ 
White 
ppt. 



\itli II' I and a little 
add Klin, filter. 



Precipitate 

Ma Si t a. 

i ollect, wash dissol e in 

ll< II .",, add excess of 

~ K 2 Cr0 4 , filter. 



Filtrate 

Mg Li K Na MI,. 

ldd(NH 4 .HAs0 4 , stir. filter 



Yellow. 



Precipitate 

i o Ni. 
Dissolve in lit I, 

and proceed „- 
directed Oil page 



X: 

. WLite 



Ppt. I'ilt. 

Sr. I 'a. 

White Add 

Nil, lit.., 

I Nil. L.C,. I 



Filtrate 
Li K Na NH, 
Evaporate to small 
hulk. A.MN'H.HO. 



-'1.2. ignite, dissolve 

K l.y Ptt i,. 

Na by rlanie. 

NH 4 in original 

solution. 



. 



ANALYTICAL MEMORANDA. 259 

That on p. 258 is a mere outline of the other two tables. It gives 
the position of the metals in relation to each other, and will much 
aid the memory in recollecting that relation. 

The analysis of solutions containing only one metal will, as 
already stated, serve to impress the memory with the characteristic 
tests for the various metals and other radicals and familiarize the 
mind with chemical principles. Medical students and junior phar- 
maceutical students seldom have time to go farther than this. More 
thorough analytical and general chemical knowledge is only acquired 
by working on such mixtures of bodies as are met with in actual 
practice, beginning with solutions which may contain any or all of 
the members of a group (see previous pages), then examining solu- 
tions containing more than one group, and finally analyzing liquids 
in which are dissolved several salts of any of the common or rarer 
metals. 

The author cannot too strongly recommend students thoroughly 
to master the art of analysis, not only on account of its direct value, 
but because its practice enables the learner rapidly and soundly to 
acquire a good knowledge of Chemistry and greatly to improve his 
general mental faculties. 



General and Special Memoranda relating to the 
preceding Analytical Tables. 

General Memoranda. 

These charts are constructed for the analysis of salts more or less 

soluble in water. The student has still to learn how substances 

insoluble in water are to be brought into a state of solution ; but, 
once dissolved, their analysis is effected by the same scheme as that 
just given. The tables, especially the longer, folded one, may 
therefore be regarded as fairly representing the method by which 
metallic constituents of chemical substances are separated from each 
other and recognized. The methods of isolation of the comple- 
mentary constituent of the salt (the reactions of non-metals and 
acidulous radicals) will form the next object of practical study. 

The general memoranda given in connection with the first table 
(p. 224) are equally applicable to this extended second table, and 
should again carefully be read through. 

Special Memoranda. 

The hydrochloric-acid precipitate may at first include some anti- 
mony and bismuth as oxychlorides, readily dissolved, however, by 
excess of acid. If either of these elements be present, the wash- 
ings of the precipitate will probably be milky ; in that case add a 
few drops of hydrochloric acid, which will clear the liquid and make 
way for the application of the test for lead. 

The sulphuretted-hydrogen precipitate may be white, in which case 
it is nothing but sulphur ; for, as already indicated, ferric salts are 
reduced to ferrous, and chromates to the lower salts of chromium, 



260 THE METALLIC RADICALS. 

by sulphuretted hydrogen, finely divided, and, therefore, whitish 
sulphur being deposited: 

2Fe 2 Cl 6 + 2H 2 S = 4FeCl 2 + 4HC1 + S 2 ; 
4H 2 Cr0 4 + 6H 2 S + 12HC1 = 2Cr 2 Cl 6 + 16H 2 + 3S 2 . 

But the precipitate may also be colored, or even white, when only 
lead or mercury is present, through an insufficiency of sulphuretted 
hydrogen having produced oxysulphide or hydrato-sulphide, etc. 
The gas should be passed through the liquid until, even after well 
shaking, the latter smells strongly of sulphuretted hydrogen. 

The portion of the sulphuretted-hydrogen precipitate dissolved by 
ammonium sulphydrate may include a trace of copper, copper sul- 
phide being not altogether insoluble in ammonium sulphydrate. 

On adding hydrochloric acid to the ammonium sulphydrate 

solution, a white precipitate of sulphur only may be precipitated, 
the ammonium sulphydrate nearly always containing free sulphur. 
Strong hydrochloric acid does not readily dissolve small quan- 
tities of antimony sulphide out of much arsenum sulphide ; and, 
on the other hand, the strong hydrochloric acid takes into solution 
a small quantity of arsenum sulphide if much antimony sulphide 
be present. The precipitates or the original solutions should there- 
fore be examined by the other (hydrogen) tests for these elements 
if doubt exist concerning the presence or absence of either. Tin 
remains in the hydrogen bottle in the metallic state, deposited as a 
black powder on the zinc used in the experiment. The contents of 
the bottle are turned out into a dish, ebullition continued until evo- 
lution of hydrogen ceases, and the zinc- is taken up by the excess 
of sulphuric acid employed ; any tin is then filtered out, washed, 
dissolved in a few drops of hydrochloric acid, and the liquid tested 

for tin by the usual reagents. Tin may be detected in the mixed tin, 

arsenum, and antimony sulphides by the blowpipe reaction (p. 243). 

The portion of the sulphuretted-hydrogen precipitate not dissolved 
by the ammonium sulphydrate may leave a yellow semi-fused globule 
of sulphur on boiling with nitric acid. This globule may be black, 
not only from presence of mercuric sulphide, but also from enclosed 
particles of other sulphides protected by the sulphur from the action 
of the acid. It may also contain lead sulphate, produced by the 
action of nitric acid on lead sulphide. In cases of doubt the mass 
must be removed from the liquid, boiled with nitric acid till dis- 
solved, the solution evaporated to remove excess of acid, and the 

residue examined ; but usually it may be disregarded. Before 

testing for bismuth any considerable excess of acid should be 
removed by evaporation, and the residual liquid should be freely 
diluted. If no precipitate (bismuth oxynitrate) appear, ammonium 
chloride solution may be added, bismuth oxychloride more readily 

forming than even oxynitrate. Or any nitric acid or sulphuric 

acid having been neutralized by ammonia, hydrochloric acid is 
added, and then potassium iodide ; a rich orange color results if 

bismuth be present. Bismuth may also be detected in the mixed 

precipitated bismuth and lead hydrates obtained in the ordinary 
course of analysis by dissolving a portion of the precipitate in acetic 



ANALYTICAL MEMOEANDA. 261 

acid, and adding the liquid to the hot lead iodide solution mentioned 
in the reactions for bismuth (p. 255). In testing for lead by sul- 
phuric acid the liquid should be diluted and set aside for some time. 

Mercury may also be isolated by digesting the sulphuretted-hydro- 
gen precipitate in sodium sulphydrate instead of ammonium sulphy- 
drate. The arsenum, antimony, tin, and mercury sulphides are 
thus dissolved out. The mixture is then filtered, excess of hydro- 
chloric acid added to the filtrate, and the precipitated sulphides col- 
lected on a filter, washed, and digested in ammonium sulphydrate ; 
mercury sulphide remains insoluble, while the arsenum, antimony, 
and tin sulphides are dissolved. By this method copper also appears 
in its right place only, copper sulphide being insoluble in sodium 
sulphydrate. The other metals are then separated in the usual way. 

The ammonium- sulphydrate precipitate may, if the original solu- 
tion was acid, contain barium, calcium, and magnesium phosphates, 
oxalates, silicates, and borates. These will subsequently come out 
with the iron, and, being white, give the iron precipitate a light- 
colored appearance ; their examination must be conducted separately 
by a method described subsequently in connection with the treat- 
ment of substances insoluble in water. The precipitate containing 

aluminium, iron, and chromium hydrates often contains some man- 
ganese. This manganese may be detected by washing the hydrates 
to remove all trace of chlorides, boiling with nitric acid, adding 
either puce-colored lead oxide or red lead, and setting the vessel 
aside ; if manganese be present, a red or purple liquid is produced. 

Nickel sulphide is not easily removed by filtration {vide p. 236) 

until most of the excess of ammonium sulphydrate has been dissi- 
pated by prolonged ebullition. 

The ammonium-carbonate precipitate may not contain the whole 
of the barium, strontium, and calcium in the mixture unless free 
ammonia be present ; for the carbonates of those metals are soluble 
in water charged with carbonic acid. If, therefore, the liquid is 
not distinctly ammoniacal, solution of ammonia should be added. 

Neither ammonium carbonate nor hydrate wholly precipitates 

magnesian salts ; and, as partial precipitation is undesirable, a 
solvent, in the form of an alkaline salt (ammonium chloride), if not 

already in the liquid, should be added. In the chart opposite 

p. 258 strontium is ordered to be separated from calcium by adding 
to the acetic solution diluted sulphuric acid. The latter, unless 
extremely dilute, may precipitate calcium. Any such loss of cal- 
cium is in itself of little consequence, because enough calcium sul- 
phate remains in the filtrate to afford a calcium reaction when 
ammonia and ammonium oxalate are subsequently added. But the 
calcium precipitated by the sulphuric acid may be wrongly set down 
as strontium. Therefore test a little of the acetic solution for stron- 
tium by an aqueous solution of calcium sulphate, when, if no pre- 
cipitate falls after setting aside for several minutes, strontium may 
be regarded as absent. If a precipitate occurs, strontium is present ; 
the rest of the acetic solution is then tested for calcium, as directed 
in the chart, the final testing by ammonium oxalate being, of course, 

preceded by the addition of ammonia. Barium may be overlooked 

12* 



262 THE ACIDULOUS RADICALS. 

if oxidation happens to have converted any sulphur into sulphuric 
acid. 

Lithium. — The search for lithium may usually be omitted. Should 
a precipitate, supposed to be due to lithium, be obtained, it must be 
tested in a flame (= scarlet tint), as a little magnesium not infre- 
quently shows itself under similar circumstances. 

Spectral Analysis. — If present only in minute proportions, the 
lithium may also remain with the alkalies ; it can then only be 
detected by physical analysis (by a prism) of the light emitted from 
a tinged flame — by, in short, an instrument termed a spectroscope. 
Such a method of examination is called spectral analysis, a subject 
of much interest and of no great difficulty, but scarcely within the 
range of medical or pharmaceutical students ; it will be described 
briefly in connection with the methods of analyzing solid substances. 



QUESTIONS AND EXERCISES. 
Describe a general method of analysis by which the metal of a single 
salt in a solution could be quickly detected. — Give illustrations of black, 
white, light-pink, yellow, and orange sulphides. — Mention the group- 
reagents usually employed in analysis. — Under what circumstances may 
a hydrochloric precipitate contain antimony or bismuth ? — If a sulphur- 
etted-hydrogen precipitate is white, what substances are indicated? — 
Give processes for the qualitative analysis of liquids containing the fol- 
lowing substances: a. Arsenum and cadmium, b. Bismuth and anti- 
mony, c. Ferrous and ferric salts, d. Aluminium, iron, and chromium. 
e. Arsenum, antimony, and tin. /. Lead and strontium, g. Iron, so- 
dium, and arsenum. h. Mercury, manganese, and magnesium, i. Zinc, 
manganese, nickel, and cobalt, j. Barium, strontium, and calcium. 



THE ACIDULOUS RADICALS. 

Introduction. — The twenty-seven radicals which have up to this 
point mainly occupied attention are (admitting ammonium, NH 4 ) 
metals, and they have been almost exclusively studied not in the 
free state, but in the condition in which they exist in salts. More- 
over, these metals have been treated as if they formed the more 
important constituent, the stronger part, the foundation or base of 
salts. Attention has been continuously directed to the metallic or 
basylous side of salts. And, indeed, there is still one more basylous 
radical which must be mentioned, though it is usually supposed to 
play only a subordinate part in medicine — hydrogen. Unlike the 
salts of most metals, those of hydrogen (the so-called acids) are 
never, in medicine or the arts generally, professedly used for the 
sake of their hydrogen, but always for the other part of the salt, 
the acidulous side. And it is not for their basylous radical that 
these hydrogen salts are now commended to notice,* but in order to 

* It must not be forgotten that the commonest salt of any radical 
whatsoever is a salt of hydrogen, hydrogen -oxide (H2O), or hydrogen 
hydrate (HHO), water. In the reactions already performed the value 
of this compound has been constantly recognized, both for its hydrogen 



THE ACIDULOUS RADICALS. 



263 



study, under the most favorable circumstances, those acidulous 
groupings which have continually presented themselves in opera- 
tions on salts, but which were for the time of secondary importance. 
These acidulous radicals may now be treated as the primary object 
of attention ; and there is no better way of doing so than by ope- 
rating on their compounds with hydrogen, the relatively inferior 
medicinal importance of which element, as compared with potas- 
sium, iron, and other basylous radicals, will serve to give the desired 
prominence to the acidulous radicals in question.* 

Common Acids. — These salts of hydrogen (hydrogen easily dis- 
placeable, wholly or, in certain cases, in part, by ordinary metals) 
are the common, sharp, sour bodies termed acids (from the Latin 
root acies, an edge). The following table includes the formulae and 
usual names of the most important : others will be noticed subse- 
quently. A few of those mentioned are unstable or somewhat rare ; 
in such cases a common metallic salt containing the acidulous rad- 
ical may be used for reactions : 



HC1 


hydrochloric acid. 


H 2 S 


sulphydric acid.' 


HBr 


hydrobromic acid. 


H 2 S0 3 


sulphurous acid 


HI 


hydriodic acid. 


H 2 S0 4 


sulphuric acid. 


HCN 


hydrocyanic acid. 


H 2 C0 3 ? 


carbonic acid. 


HN0 3 


nitric acid. 


H 2 C 2 4 


oxalic acid. 


HC 2 H 3 2 


acetic acid.f 


H 2 C 4 H 4 6 


tartaric acid. 



H 3 C 6 H 5 7 citric acid. H 3 P0 4 phosphoric acid. H 3 B0 3 boric acid. 

The usual names are here retained for these acids, but in studying 
their chemistry and chemical relations to other salts they are usefully 



and for its oxygen, but most of all as the vehicle or medium by which 
nearly all other atoms are enabled to come into that contact with each 
other without which their existence would be almost useless ; for some 
atoms are like some animals — out of water they are as inactive as fishes. 
It is true that both fishes and salts have usually to be removed from 
water to be utilized by man, but before they can be assimilated, either 
as food or as medicine, they must again seek the agency of water — in 
becoming dissolved. 

* Actually, it is as difficult to determine the relative importance of the 
different atoms or groups of atoms in a molecule as it is of the different 
parts or members of an animal or vegetable, the different units or societies 
in a community, the different planets or solar systems of the universe ; 
nay, the different pieces or parts of an engine or the different pigments 
or portions of a picture : V union fait la force. 

f The hydrogen on the acidulous side must not be confounded with 
the basylous hydrogen in all these hydrogen salts or acids ; the two per- 
form different functions. Hydrogen in the acidulous portion is like the 
hydrogen in the basylous radical ammonium : it has combined w r ith 
other atoms to form a group which plays more or less the part of an 
elementary radical. Cobalt, chromium, iron, platinum, etc. resemble 
hydrogen in this respect, in often uniting with other atoms to form 
definite acidulous radicals in which the usual basylous character of the 
metals has for the time disappeared. In hydrides (p. 124) hydrogen 
itself is an acidulous radical. 

X Synonyms : hydrosulphuric acid and sulphuretted hydrogen. 



264 THE ACIDULOUS RADICALS. 

spoken of by such more purely chemical names, as (for hydrochloric 
acid) chloride of hydrogen or hydrogen chloride, hydrogen nitrate, 
and so on — hydric or hydrogen sulphate, dihydric tartrate, trihydric 
phosphate, etc. 

A prominent point of difference will at one be noticed between 
the basylous radicals met with up to the present time and the acid- 
ulous groupings included in the above tabular list. The former are 
nearly all elements, ammonium only being a compound ; the latter 
are mostly compounds, chlorine, bromine, iodine, and sulphur being 
the only elements. This difference will not, however, be so apparent 
when the chemistry of alcohols, ethers, and such bodies has been 
mastered, for they may be regarded as salts of compound basylous 
radicals. 

Rarer Acids. — The above acids contain the only acidulous group- 
ings that commonly present themselves in analysis or in pharma- 
ceutical operations. There are, however, several other acids (such 
as hypochlorous, nitrous, hypophosphorous, valerianic, benzoic, gal- 
lic, tannic, uric, hyposulphurous, hydroferrocyanic, hydroferricyanic, 
lactic, etc.) with which it is desirable to be more or less familiar ; 
reactions concerning these will therefore be described. Arsenous, 
arsenic, stannic, manganic, and chromic acids have already been 
treated of in connection with the metals they contain ; in practical 
analysis these acids always become sufficiently altered for their 
metals to come out among the basylous radicals. 

Quantivalence. — A glance at the foregoing table is sufficient to 
show the quantivalence of the acidulous radicals there mentioned. 
The first six are clearly univalent ; then follow six bivalent, leaving 
three trivalent. 

These all combine with equivalent amounts of basylous radicals 
to form various salts ; hence they may be termed monobasylous, 
dibasylous, and tribasylous radicals. The acids themselves were 
formerly spoken of as monobasic, bibasic, and tribasic respectively, 
or monobasic and polybasic, in reference to the amount of base 
(hydrates or oxides) they could decompose ; but the terms are no 
longer definite, and hence but little used in mineral chemistry. 

Antidotes. — The antidotes in case of poisoning by the strong acids 
will obviously be non-corrosive alkaline substances, as soap and 
water, magnesia, and common washing " soda" or other carbonates. 
Vinegar, lemon-juice, and weak and non-corrosive acids would be 
the appropriate antidotes to caustic alkalies. 

Analysis. — The practical study of the acidulous side of salts will 
occupy far less time than the basylous. Salts will then be briefly 
examined as a whole. 

Caution. — Once more : it is only for convenience in the division 
of chemistry for systematic study that salts may be considered to 
contain basylous and acidulous radicals, or separate sides, so to 
speak ; for we possess no absolute knowledge of the internal 
arrangement of the atoms (admitting that there are such things) 
in the molecule of the salt. We only know that certain groups of 
atoms may be transferred from compound to compound in mass 
(that is, without apparent decomposition) ; hence the assumption 



CHLORIDES. 265 

that these groups are radicals. A salt is probably a whole, having 
no such sides as those mentioned. 



QUESTIONS AND EXEECISES. 



Mention the basylous radical of acids. — Give illustrations of univalent, 
bivalent, and trivalent acidulous radicals or nionobasylous, dibasylous, 
and tribasylous radicals. — What is. the difference between an elementary 
and a compound acidulous radical ? — Name the grounds on which salts 
may be assumed to contain basylous and acidulous radicals. 



HYDROCHLORIC ACID AND OTHER CHLORIDES. 

Formula, HC1. Molecular weight,* 36.5. 

The acidulous radical of hydrochloric acid and of other chlorides 
is the element chlorine (CI). It occurs in nature chiefly as sodium 
chloride (NaCl), either solid under the name rock-salt, mines of 
wmich are not uncommon, or in solution in the water of all seas. 
Common table-salt is more or less pure sodium chloride in minute 
crystals. Chlorine, like hydrogen, is univalent (CY); its atomic 
weight is 35.5. Its molecule is symbolized thus, Cl 2 . 

Reactions. 
Hydrochloric Acid. 

Synonyms. — Hydrogen Chloride ; Chloride of Hydrogen ; Muriatic 
Acid ; Chlorhydric Acid. 

First Synthetical Reaction. — To a few fragments of sodium 
chloride in a test-tube or a small flask add about an equal weight 
of sulphuric acid ; colorless and invisible gaseous hydrochloric 
acid is evolved, a sodium sulphate remaining. Adapt to the 
mouth of the vessel, by a perforated cork, a piece of glass 
tubing bent to a right angle, heat the mixture, and convey the 
gas into a small bottle containing a little water ; solution of 
hydrochloric acid results. 

Nad + H 2 S0 4 = HC1 + NaHSO, 

Sodium Sulphuric Hydrochloric Acid sodium 

chloride. acid. acid. sulphate. 

Hydrochloric Acid. — The product of this operation is the nearly 
colorless and very sour liquid commonly termed hydrochloric acid. 
When of certain given strengths (estimated by volumetric analysis), 
it forms Acidum Hydrochloricum, U. S. P. (Muriatic Acid), and 
Acidum Hydrochloricum Dilutum, U. S. P. The former has a specific 
gravity of about 1.163 (1.1578), and contains 31.9 per cent, of real 
acid ; the latter, sp. gr. 1.050, with 10 per cent, of the real acid, is 
made by diluting 6 fluid parts of the strong acid with 13 of water. 

* The weight of a molecule is the sum of the weights of its atoms. 



266 



THE ACIDULOUS RADICALS. 



The above process is that of the manufacturer, larger vessels being 
employed, and the gas being freed from any trace of sulphuric acid 
by washing. Other chlorides yield hydrochloric acid when heated 
with sulphuric acid, but sodium chloride is always used because 
cheap and common. 

Fig. 37. 




Preparation of Hydrochloric Acid. 



Common yellow hydrochloric acid is a by-product in the manufac- 
ture of sodium carbonate from common salt by the process in which 
sodium chloride is first converted into sulphate, hydrochloric acid 
being liberated. This impure acid is liable to contain iron, arsenum, 
fixed salts, sulphuric acid, sulphurous acid, nitrous compounds, and 
chlorine. 

The process for the preparation of hydrochloric acid is as follows : 
it may be carried out by the student with about one-twelfth of the 
quantities mentioned : 

" Take of sodium chloride, dried, 48 ounces, sulphuric acid 44 
fluidounces, water 36 fluidounces, distilled water 50 fluidounces. 
Pour the sulphuric acid slowly into 32 ounces of the water, and, 
when the mixture has cooled, add it to the sodium chloride previ- 
ously introduced into a flask having the capacity of at least one 
gallon 5 connect the flask by corks and a bent glass tube with a three- 
necked wash-bottle, furnished with a safety-tube, and containing the 
remaining 4 ounces of the water (or let the flask-tube pass loosely 
through a wider tube fixed in the cork of the wash-bottle, as shown 
in Fig. 37) : then, applying heat to the flask, conduct the disengaged 
gas through the wash-bottle into a second bottle containing the dis- 
tilled water by means of a bent tube dipping about half an inch 
below the surface, and let the process be continued until the product 
measures 66 ounces or the liquid has acquired a specific gravity of 
1.16. The bottle containing the distilled water must be kept cool 
during the whole operation." — B. P. 

The modification of wash-bottle shown in the figure allows of the 
easy insertion or removal of a delivery tube. The wider tube there 
shown, or an ordinary tube-funnel, also acts as a safety-tube by 



CHLORIDES. 267 

admitting the air the moment there is any tendency in the water in 
the receiver to be forced back on account of a too rapid absorption 
of the gas. The time of the student will be saved if hydrochloric 
acid already in stock be placed in the wash-bottle instead of water. 

Invisible gaseous hydrochloric acid forms visible grayish-white 
fumes on coming into contact with air. This is due to combination 
with the moisture of the air. The intense greediness of hydrochloric 
gas and water for each other is strikingly demonstrated on opening 
a test-tube full of the gas under water ; the latter rushes into and 
instantly fills the tube. If the water is tinged with blue litmus, the 
acid character of the gas is prettily shown at the same time. The 
test-tube, which should be perfectly dry, may be filled from the 
delivery-tube direct, for the gas is somewhat heavier than, and there- 
fore readily displaces, air. The mouth may be closed by the thumb 
of the operator. At low temperatures hydrochloric acid and water 
form a crystalline compound, HC1,2H 2 0. 

Note. — The process includes the use of as much sulphuric acid as 
is necessary for the production of acid sodium sulphate (NaHSOJ, 
which remains in the generating vessel. A hot solution of this 
residue, neutralized by sodium carbonate, filtered and set aside, 
yields normal sodium sulphate (Soclii Sulphas or Sodium Sulphate, 
U. S. P., the old sulphate of soda, " Glauber's salt"), in the form of 
transparent, oblique, efflorescent prisms (Na 2 SO 4 ,10H 2 O). 

2NaHS0 4 -f Na 2 C0 3 = 2Na 2 S0 4 + H 2 + C0 2 

Acid sodium Sodium Sodium Water. Carbonic 

sulphate. carbonate. sulphate. acid gas. 

Chlorine. 

Second Synthetical Reaction. — To some drops of hydrochloric 
acid (that is, the common aqueous solution of the gas) add a 
few grains of black manganese oxide, and warm the mixture ; 
chlorine, the acidulous radical of all chlorides, is evolved, and 
may be recognized by its peculiar odor or irritating effect on 
the nose and air-passages. 

4HC1 + Mn0 2 = Cl 2 + 2H 2 + MnCl 2 . 

Chlorine-water. — This is the process of the Pharmacopoeia for the 
production of chlorine-water (Aqua Chlori, U. S. P.), the gas being 
first washed and then passed into water. 1 ounce of oxide to 6 
fluidounces of acid diluted with 2 of water, and the gas passed 
through a wash-bottle containing about 2 ounces of water, yields 
enough chlorine to produce about 1J pints of chlorine- water. (On 
this small scale less than half the acid is utilized through incom- 
plete decomposition of the materials, and especially through incom- 
plete absorption of the chlorine gas.) Chlorine slowly decomposes 
water with production of hydrochloric acid and oxygen gas 5 hence 
for medicinal purposes the solution should be freshly prepared ; it 
is best preserved in a green-glass well-stoppered bottle in a cool and 
dark place. At common temperatures (60° F.), if fresh and thor- 
oughly saturated, chlorine-water contains more than twice (2.3) its 



2NaCl 


+ 


H 2 S0 4 


= 


Na 2 S0 4 


+ 


2HC 


Mn0 2 


+ 


H 2 S0 4 


= 


MnS0 4 


+ 


H 2 


then the 2HC1 


+ 





= 


H 2 


+ 


Cl 2 ; 



268 THE ACIDULOUS RADICALS. 

bulk of chlorine, or less than 1 per cent, (about 0.75) by weight. 
Chlorine passed into cold water yields crystals of hydrous chlorine 
(C15H 2 0), and these, when heated under pressure, give an upper 
layer of chlorine-water and a lower layer of liquid chlorine. 

Note. — To obtain the chlorine from other chlorides sulphuric acid, 
as well as black manganese oxide, must be added. Hydrochloric 
acid is first formed. The action described in the foregoing equation 
then goes on, except that half instead of the whole of the oxygen 
from the black oxide is employed for the removal of the hydrogen 
from the chlorine of the hydrochloric acid, the other half being 
taken up by the hydrogen of the sulphuric acid. Thus, assuming 
common salt to be the chloride used, the following equations may 
represent the supposed steps of the process : 

4- 2HC1. 

+ 0; 

+ ci 25 

or the whole may be included in one equation. 

2NaCl -f Mn0 2 + 2H 2 S0 4 = Na 2 S0 4 + MnS0 4 + 2H 2 + 01,. 

This reaction may occasionally have analytical interest, a very 
small quantity of combined chlorine being recognized by its means. 
But the following test is nearly always applicable for the detection 
of this element, and leaves nothing to be desired in point of delicacy. 

Analytical Keactions (Tests). 

To a drop of hydrochloric acid, or to a dilute solution of 
any other chloride, add solution of silver nitrate ; a white 
curdy precipitate (silver chloride, AgCl) falls. Pour off trie 
supernatant liquid, add nitric acid, and boil ; the precipitate 
does not dissolve. Pour off the acid and add dilute ammonia ; 
the precipitate quickly dissolves. Neutralize the solution by 
an acid ; the curdy precipitate again appears. 

The formation of this white precipitate, its appearance, insolu- 
bility in boiling nitric acid, solubility in solution of ammonia or its 
carbonate, and reprecipitation by an acid, form abundant evidence 
of the presence of chlorine. Its occurrence as a chloride of a metal 
is determined by testing for the metal with the appropriate reagents ; 
its occurrence as hydrochloric acid is considered to be indicated by 
the odor, if strong, and the sour taste, if weak, of the liquid, and 
the action of the liquid on blue litmus-paper, which, like other 
acids, it reddens. If hydrochloric acid be present in excessive 
quantity, it will, in addition to the above reactions, give rise to 
strong effervescence on the addition of a carbonate, a chloride being 
formed. The chlorine in insoluble chlorides, such as calomel, 
"white precipitate," etc., may be detected by boiling with alkali, 
filtering, acidulating the filtrate by nitric acid, and then adding the 
silver nitrate. 

Antidotes. — In cases of poisoning by strong hydrochloric acid 



BROMIDES. 269 

solution of sodium carbonate (common washing-soda) or a mixture 
of magnesia and water may be administered as an antidote. 



QUESTIONS AND EXEECISES. 

The official hydrochloric acid contains 31.8 per cent, by weight of gas, 
and its specific gravity is 1.16 : work out a sum showing what volume 
of it will be required, theoretically, to mix with black manganese oxide 
for the production of 1 gallon of chlorine-water, 1 fmidounce of which 
contains 2.66 grains of chlorine. Ans., 5h fl. ozs. nearly (5.4) — Why does 
hydrochloric acid gas give visible fumes on coming into contact with 
air ? — How much sodium chloride will be required to furnish 1 pound 
of chlorine ? — Give the analytical reactions of chlorides. — What anti- 
dotes may be administered in cases of poisoning by hydrochloric acid? 



HYDROBROMIC ACID AND OTHER BROMIDES. 

Formula of Hydrobromic Acid, HBr. Molecular weight, 81. 

Bromine. — Source, Preparation, and Properties. — The acidulous 
radical of hydrobromic acid and other bromides is the element bro- 
mine, Br. (Bromum, IT. S. P.). It occurs in nature chiefly as mag- 
nesium bromide (MgBr 2 ) in sea-water and certain saline springs, 
and is commonly prepared from the bittern, or residual liquors, of 
salt-works. It may be liberated from its compounds by the process 
for chlorine from chlorides — that is, by heating with black man- 
ganese oxide and sulphuric acid (see note on p. 268). It is a dark- 
red, volatile liquid, emitting an odor more irritating, if possible, 
than chlorine — of specific gravity 2.97 to 3.14; boiling-point, 135— 
145° F. 

If bromine be added to an excess of potassium or sodium hydrate 
solution, it should combine to form a permanently clear liquid, 
without the separation of oily drops or the development of an odor 
resembling that of chloroform (absence of bromoform or other 
organic bromine compounds). 

If an aqueous solution of bromine be shaken with a slight excess 
of reduced iron until it becomes nearly colorless, the filtered liquid, 
on the addition of a small amount of ferric chloride and of starch 
mucilage, should not assume a blue color (absence of iodine). 

If 1 cc. of a saturated aqueous solution of bromine be diluted with 
9 cc. of water, then mixed with 3 cc. of ammonium carbonate T.S. 
and 5 cc. of decinormal silver nitrate V.S., and the whole actively 
shaken, the filtered liquid, when supersaturated with nitric acid, 
should not become more than opalescent, nor separate a flocculent 
precipitate within three, minutes (absence of more than 3 per cent, 
of chlorine). 

Quantivalence. — The atom of bromine, like that of chlorine, is 
univalent (Br'). The atomic weight of bromine is 80. Free bromine 
has the molecular formula Br 2 . 

Hydrobromic Acid. — Hydrogen bromide, or hydrobromic acid, 
may be made by decomposing phosphorus bromide by water: 



270 



THE ACIDULOUS RADICALS. 



PBr 5 -f- 4H 2 = 5HBr + H 3 P0 4 . A small quantity is prepared by 
placing seven or eight drops of bromine at the bottom of a test-tube, 
putting in fragments of glass to the height of about an inch or two, 
then ten or eleven grains of phosphorus, then another inch of glass, 
and finally a couple of inches of glass fragments slightly wetted 
with water, a delivery-tube being fitted by a cork. The phosphorus 
combines readily, almost violently, with the bromine as soon as the 
vapor of the latter, aided by a little warmth from a flame, rises to 
the region of the phosphorus. The phosphorus bromide thus formed 
then suffers decomposition by the water of the moist glass, phos- 
phoric and phosphorous acids being produced. The hydrobromic 
acid gas passes over (heat being applied in the after part of the 
operation) and may be condensed in water or in solution of ammonia. 
The latter solution on evaporation yields ammonium bromide. 

Fig. 38. 




Preparation of Hydrobromic Acid. 

Acidum Hydrobromicum Dilutum, U. S. P. — Pass sulphuretted- 
hydrogen gas through bromine covered with water, and, when all 
bromine has disappeared, distil the mixture. The distillate, when 
diluted until it has a sp. gr. of 1.300, contains 33 per cent, of HBr. 
Diluted until the sp. gr. is 1.077, it contains 10 per cent, of HBr, 
and is then of official strength. 

10Br 2 + 4H 2 S + 8H 2 = 20HBr + 2H 2 S0 4 + S 2 . 

Potassium Bromide (KBr) is very largely employed in pharmacy, 
and is the salt, therefore, which may be used in studying the reac- 
tions of this acidulous radical. The official method of making the 
salt has been alluded to under the salts of potassium (p. 77). 

Other bromides are seldom used ; they may be prepared in the 
same way as, and closely resemble, the corresponding chlorides or 
iodides. 

Sodium Bromide crystallizes in anhydrous cubes (NaBr) from 
solutions at 110° or 120° F.. and in hydrous prisms (NaBr,2H 2 0) 
at ordinary temperatures. 

Ammonium Bromide (NH 4 Br) (Ammonii Bromidum, U. S. P.) is 
prepared by agitating iron wire with a solution of bromine until 
the odor of bromine can be no longer perceived, adding solution of 
ammonia, filtering, and evaporating the filtrate to dryness. It forms 



BROMIDES. 271 

a white granular salt, which becomes slightly yellow on exposure 
to air, is readily soluble in water, less so in spirit, and, when heated, 
sublimes. Ammonium bromide or iodide may also be made by 
mixing equivalent quantities of strong hot, aqueous solutions of the 
corresponding potassium salts and of ammonium sulphate. To the 
cooled liquids rectified spirit is added, which precipitates the potas- 
sium sulphate. The spirit recovered by distillation of the clear 
liquid leaves the required salt as a residue in the retort. 

Calcium Bromide, CaBr 2 {Calcii Bromidum, U. S. P.), may be 
prepared by neutralizing hydrochloric acid by calcium hydrate or 
carbonate, filtering, and evaporating to dryness ; or by uniting 
bromine with iron, boiling the aqueous solution with lime until the 
mixture is red, filtering, and evaporating. It is a white deliquescent 
granular salt, soluble in water and in alcohol. 

Solution of Bromine, B. P., 10 minims in 5 ounces, or Bromine- 
water, U. S. P., 1 cc. in 100 cc, is an aqueous solution, bromine 
being slightly soluble in water. 

Hypobromites, Bromates, and Perbromates, analogous to hypo- 
chlorites, chlorates, and perchlorates, are producible. 

Bromates, occurring as an impurity in bromides, are detected by 
dropping diluted sulphuric acid on to the salt, when a yellow color, 
due to free bromine, is produced immediately if bromates are 
present. 

Analytical Reactions (Tests). 

First Analytical Reaction. — To a few drops of a solution of 
a bromide (KBr or NH 4 Br) add solution of silver nitrate ; a 
yellowish-white precipitate (silver bromide, AgBr) falls. Treat 
the precipitate successively with nitric acid and dilute ammo- 
nia, as described for the silver chloride ; it is only sparingly 
dissolved in ammonia. 

Second Analytical Reaction. — To solution of a bromide add 
a drop or two of chlorine-water or a bubble or two of chlorine 
gas ; then add a few drops of chloroform or ether or carbon 
bisulphide, shake the mixture, and set the test-tube aside : the 
chlorine, from the greater strength of its affinities, displaces 
the bromine, which is dissolved by the chloroform, etc., the 
solution falling 'to the bottom of the tube in the case of the 
heavy chloroform or carbon bisulphide, or rising to the top in 
the case of the light ether. Either solution has a distinct yel- 
low or reddish-yellow or red color, according to the amount of 
bromine present. 

Notes. — This reaction serves for the isolation of bromine when 
mixed with many other substances. Excess of chlorine must be 
avoided, as colorless bromine chloride is then formed. Iodides give 
a somewhat similar appearance ; the absence of iodine must there- 
fore be ensured by a process given in the next section. The above 
solution in chloroform or ether may be removed from the tube by 



272 THE ACIDULOUS RADICALS. 

drawing up into a pipette (small pipe — a narrow glass tube, usually- 
having a bulb or expanded portion in the centre), the bromine fixed 
by the addition of a drop of solution of potash or soda, the chloro- 
form or ether evaporated off, and the residue tested as described in 
the next reaction. 

Third Analytical Reaction. — Liberate bromine from a bro- 
mide by the cautious addition of chlorine or chlorine-water, 
then add a few drops of cold " mucilage of starch " (vide 
Index) ; a yellow combination of bromine and starch, commonly 
termed " starch bromide," is formed. 

The above reaction may be varied by liberating the bromine 
by a little black manganese oxide and a drop of sulphuric acid, 
the upper part of the inside of the test-tube being smeared 
over with the mucilage of starch. Even sulphuric acid alone, 
if strong, liberates bromine from a bromide, the hydrogen of 
the hydrobromic acid first produced uniting with the oxygen 
of the sulphuric acid — the latter being reduced to sulphurous 
acid or even to hydrosulphuric acid. 



HYDRIODIC ACID AND OTHER IODIDES. 

Formula of Hydriodic Acid, HI. Molecular weight, 128. 

Som°ce. — The acidulous radical of hydriodic acid and other iodides 
is the element iodine (I). It occurs in nature as sodium and 
magnesium iodides in sea-water. Sea-weeds, sponges, and other 
marine organisms, which derive much of their nourishment from 
sea-water, store up iodides in their tissues, and it is from the ashes 
of these that supplies of iodine (Iodum, U. S. P.) are obtained. 
Mineral iodides also are met with, and iodates occur in crude cubic 
nitre. 

Process. — The sea-weed ash or kelp is treated with water, insolu- 
ble matter thrown away, and the decanted liquid evaporated and 
set aside to allow of the deposition of most of the sodium and potas- 
sium sulphates, carbonates, and chlorides. The residual liquor is 
treated with excess of sulphuric acid, which causes evolution of car- 
bonic and sulphurous or sulphuretted gases, deposition of sulphur 
and more sodium sulphate, and formation of hydriodic acid. To the 
decanted liquid is added black manganese oxide, and the mixture is 
then slowly distilled ; the iodine sublimes, and is afterward purified 
by resublimation. 

2HI + Mn0 2 + H 2 S0 4 = MnS0 4 + 2H 2 + I 2 . 

The analogy of chlorine, bromine, and iodine is well indicated by 
the fact that each is obtained from its compounds by the same reac- 
tion. Iodine is liberated from any iodide as bromine from bromides 
or chlorine from chlorides — namely, by the action of black manganese 
oxide and sulphuric acid. 

Properties. — Iodine is a crystalline purplish-black substance ; its 



IODIDES. 273 

vapor, readily seen on heating a fragment in a test-tuble, is dark- 
violet. Its vapors are irritating to the lungs, but a trace may be 
inhaled with safety ( Vapor Iodi, B. P.). It melts at about 230° F., 
boils at about 392°, and is entirely volatilized, the first portions con- 
taining any iodine cyanide or cyanogen iodide that may be, though 
very rarely is, present. The latter body occurs in slender, colorless 
prisms, emitting a pungent odor. 

" A solution of iodine in chloroform should be perfectly clear and 
limpid (absence of moisture)." 

The presence of cyanogen, chlorine, or bromine is determined as 
follows : When shaken with distilled water it should not communi- 
cate to the latter more than a light brownish tinge, and no deep 
brown color (absence of iodine chloride). If the iodine be re- 
moved from this dilute aqueous solution by agitation with carbon 
disulphide, and after the separation of the latter some dilute solu- 
tion of ferrous sulphate with a trace of ferric chloride be added, 
finally soda solution, and the whole supersaturated with hydro- 
chloric acid, no blue precipitate should make its appearance (absence 
of iodine cyanide). If iodine be dissolved in sulphurous acid, the 
solution strongly supersaturated with ammonia, and completely pre- 
cipitated by silver nitrate, the filtrate, on being supersaturated with 
nitric acid, should not at once become more than faintly cloudy 
(absence of more than traces of chlorine or bromine). " Triturate 
0.25 grm. of finely-powdered iodine in 10 cc. of water, and filter off 
the solution ; to the aqueous filtrate, in a test-tube, add a slight 
excess of silver nitrate, shake actively, allow the precipitate to sub- 
side, and, having poured off the clear, supernatant liquid completely, 
shake the precipitate with a mixture of 1 cc. of ammonia-water and 
9 cc. of water, and filter. Upon the addition of a slight excess of 
nitric acid to the filtrate, not more than a slight opalescence should 
make its appearance (limit of chlorine or bromine)." — U. S. P. 

This latter reaction is applied for the detection of chloride or 
bromide in iodides, omitting the addition of sulphurous acid. 

Quantivalence. — The atom of iodine, like those of bromine and 
chlorine, is univalent* (F). The atomic weight of iodine is 127 ; its 
molecular formula, I 2 . 

Hydrogen Iodide, or Hydriodic Acid, is a heavy, colorless gas. 
Its solution in water may be made by passing sulphuretted hydrogen 
into water in which iodine is suspended, the chief reaction being 
2H 2 S + 2I 2 — S 2 + 4HI. (See the analogous reaction for HBr, 
p. 270.) 

;ff There is a compound of iodine having the formula ICI3. Iodine 
would at first sight, therefore, seem to be a trivalent element (I"')> and 
bromine and fluorine, from their close chemical analogy with iodine, 
would necessarily be regarded as trivalent also. From this aspect the 
position of chlorine would be anomalous. Probably, however, the com- 
pound is only a molecular combination of true iodine chloride, IC1, with 
added chlorine, CI2. Iodine forms, with potassium iodide, a periodide 
or tri-iodide, KI3, which may be obtained in lustrous prismatic crystals. 
This, too, may have the formula KIJ2. A mercuric hexiodide (Hgl6, 
perhaps Hgl2,l2,l2) is also known ; and an ammonium periodide, NEUI,l2 : 
both, probably, only " additive" compounds. (See p. 139.) 



274 THE ACIDULOUS RADICALS. 

Hydriodic acid may also be prepared by placing 20 parts of iodine 
and 2 of water in a retort the neck of which points upward, and the 
end of the neck of which is connected by a glass tube with a bottle 
or other vessel containing a little water. Into the tubulure of the 
retort is passed, at first a drop at a time, a mixture of 1 part of red 
phosphorus with 2 of water. Abundance of hydriodic acid is 
evolved on the application of a gentle heat, and falls into and dis- 
solves in the water in the receiver. Phosphoric acid remains. 
P 2 + 5I 2 + 8H 2 = 10HI -f 2H 3 P0 4 . (See the analogous reaction 
for HBr, p. 269.) 

Or iodine may be dissolved in carbon bisulphide in a tall cylinder, 
water added, and sulphuretted hydrogen passed through the mixture. 
The water dissolves the hydriodic acid produced, the bisulphide 
retaining the separated sulphur. The aqueous solution only needs 
boiling for two or three minutes to remove excess of sulphuretted 
hydrogen. 

Syrupus Acidi Hydriodici, U. S. P., contains 1 per cent, of real 
acid. Potassium Iodide, or Iodide of Potassium (KI), is largely 
used in medicine, and hence is the most convenient iodide on which 
to experiment in studying the reactions of this acidulous radical. 
Solid iodine itself might be taken for the purpose, but its use and 
action in that state having already been alluded to in describing 
potassium, cadmium, and mercury iodides, its analytical reactions 
in the combined condition are those which may now occupy atten- 
tion. 

Ammonii Todidum, U. S. P., Ammonium Iodide or Iodide of 
Ammonium, may be made by decomposing the two bodies, potassium 
iodide and ammonium sulphate, which give ammonium iodide and 
potassium sulphate ; the latter salt is separated by adding alcohol to 
the cooled solution, when, by reason of its insolubility in alcohol, it 
crystallizes out, and the separated solution of ammonium iodide is then 
evaporated to dryness. It occurs usually in minute white crystal- 
line cubes. 

Solution of Iodine.— Iodine is slightly soluble in water (iodine- 
water), and readily soluble in an aqueous solution of potassium 
iodide. 5 parts of iodine and 10 of potassium iodide, dissolved in 85 
of distilled water, form Liquor- Iodi Compositus, U. S. P. ( ; ' Lugol's 
Solution''); 4 parts of iodine and 1 of potassium iodide, rubbed 
with 2 parts of water and 93 of benzoated lard, form Unguentum 
Iodi, U. S. P. It is more soluble in spirit (Tinctura Iodi, U. S. P.) 
or in a spirituous solution of potassium iodide (Tinctura Iodi, B. P.). 
It combines with sulphur, forming an unstable grayish-black solid 
iodide (S 2 I 2 ), having a radiated crystalline structure (Sidphuris 
lodidum, U. S. P., or Sulphur Iodide). If 100 parts be thoroughly 
boiled with water, the iodine will pass off in vapor, and about 20 
parts of sulphur remain. — B. P. and U. S. P. 

Analytical Ke actions (Tests). 

First Analytical Reaction. — To a few drops of an aqueous 
solution of an iodide (e. g. KI) add solution of silver nitrate ; 



IODIDES. 275 

a light yellow precipitate (silver iodide, Agl) falls. Pour away 
the supernatant liquid and treat the precipitate with nitric acid ; 
it is not dissolved. Pour away the acid, and then add dilute 
ammonia ; it is only sparingly dissolved. 

This reaction is useful in separating iodine from most other 
acidulous radicals, but does not distinguish iodine from bromine. 

The presence of chloride in silver iodide may be detected by boil- 
ing with dilute solution of ammonium carbonate, filtering off the 
insoluble silver iodide, and saturating the filtrate with nitric acid ; 
any silver chloride is then precipitated. 

Ammonia, it will be remembered, dissolves silver chloride readily ; 
hence the presence of potassium chloride in bromide or iodide may 
be detected by dissolving in water, adding excess of silver nitrate, 
collecting the precipitate, washing, digesting in ammonia, filtering, 
and adding excess of nitric acid to the filtrate ; more than a trace of 
white curdy precipitate indicates chloride (of potassium). Silver 
bromide and iodide are, however, slightly soluble in ammonia. 
Better processes are given on pp. 276-279. 

Second Analytical Reaction. — Liberate iodine from an iodide 
by the cautious addition of chlorine, then add mucilage of 
starch ; a deep-blue combination of iodine and starch, com- 
monly termed u starch iodide," is formed. 

Starch is highly sensitive to the action of iodine ; this reaction is 
consequently very delicate and characteristic. Heat decomposes 
the blue compound. Excess of chlorine must be avoided or color- 
less iodine chloride will be produced. Nitrous acid, or a nitrite 
acidulated with sulphuric acid, may be used instead of chlorine. 
Concentrated sulphuric acid also liberates iodine from iodides, the 
hydrogen of the hydriodic acid first produced uniting with the 
oxygen of the sulphuric acid — the latter (H 2 S0 4 ) being reduced to 
sulphurous acid (H 2 S0 3 ), or even to hydrosulphuric acid (H 2 S). 

In testing bromine for iodine the bromine must be nearly all con- 
verted into hydrobromic acid by dilute solution of sulphurous acid, 
or be nearly all removed by solution of soda, before the mucilage 
of starch is added. 

Ozone (0 3 ). — Papers soaked in mucilage of starch containing 
potassium iodide form a test for free chlorine and nitrous acid, 
and are also employed by meteorologists to detect an allotropic or 
physically polymeric and energetic form of oxygen, termed by 
Schonbein ozone (from b^u, ozo, I smell). This substance liberates 
iodine from the potassium iodide (with formation of starch iodide), 
and is supposed to occur normally in the atmosphere, the salubrity 
or insalubrity of which is said to be dependent to some extent on 
the presence or absence of ozone. The possible occurrence of 
nitrous or chlorinoid gases in the air, however, renders the test 
untrustworthy. Houzeau proposes to test for ozone by exposing 
litmus-paper of a neutral tint soaked in a dilute solution of potas- 
sium iodide : the potash set free by action of the ozone turns the 



276 



THE ACIDULOUS RADICALS. 



paper blue. The same paper without iodide would indicate the 
extent to which the effect might be due to ammonia-vapor. Ozone, 
or, rather, ozonized air, is produced artificially in large quantities 
on passing air through a box (Beane's ozone-generator) highly 
charged with electricity. In the latter operation condensation of 
the volume of air, or rather of the oxygen in the air, occurs. Small 
quantities are obtained by exposing in a loosely-closed bottle a stick 
of phosphorus partly covered by water, but the product is mixed 
with hydrogen peroxide. Ozone is a powerful bleaching, disinfect- 
ing, and general oxidizing agent; insoluble in water, soluble in 
oils of turpentine, cinnamon, and some other liquids. From exper- 
iments that have been made by Soret on the specific gravity of 
ozone, its molecular formula would seem to be 3 , that of ordinary 
oxygen being 2 . Its smell is peculiar. 

Third Analytical Reaction. — To a neutral aqueous solution 
of an iodide add a solution containing 1 part of copper sulphate 
to 2 1 parts of ferrous sulphate, and well shake; a dirty -white 
precipitate of cuprous iodide (Cu 2 I 2 ) falls. 

2KI + 2CuS0 4 + 2FeSO, = Cu 2 I 2 + K 2 S0 4 + Fe a 3S0 4 . 

Or to the liquid containing an iodide add the solution of cop- 
per sulphate and some solution of sulphurous acid, and warm 
the mixture; cuprous iodide falls. 

2KI + 2CuS0 4 + H 2 S0 3 + H 2 = Cu 2 I 2 + 2KHS0 4 + H 2 S0 4 . 

Separation of Chlorides, Bromides-, and Iodides. — Chlorides and 
bromides are not affected in the above way : the reaction is useful, 
therefore, in removing iodine from a solution in which chlorides 
and bromides have to be sought. The total removal of iodine by 
the former of the two modifications of the process is ensured by 
supplementing the addition of the cupric and ferrous sulphates by 
a few drops of solution of potash or soda, any acid which might be 
keeping cuprous iodide in solution being thereby neutralized, ferric 
or ferrous hydrate, precipitated at the same time, not affecting the 
reaction. Occasionally, too, it may be necessary to repeat the 
process with the filtrate before the last traces of iodine are removed. 
The second modification of the process is, on the whole, to be pre- 
ferred. 

Chlorides may be separated from bromides by taking advantage 
of the ready solubility of silver chloride and the slow and slight 
solubility of silver bromide in ammonia, especially in (a fair, not a 
great, excess of) ammonia containing silver chloride. The presence 
of much silver bromide, however, considerably reduces the power 
of ammonia to dissolve silver chloride. 

Hart's Test. — (If nitrates, chlorates, bromates, or iodates are 
present, it is necessary to fuse the substance with a little 
sodium carbonate and charcoal to reduce them. If the haloids 
are united with silver, it is best to fuse with sodium carbonate 



IODIDES. 277 

and extract with water, although with iodine and bromine this 
is not absolutely necessary.) The substance is placed in the 
flask shown in the figure given in the section on the quanti- 
tative analysis of manganese oxide (vide Index), with some 
water and a few drops of solution of ferric sulphate. Into the 
bulbs are poured a few drops of dilute starch mucilage. The 
bulbs are kept cold by immersing in water in a beaker. The 
contents of the flask are then boiled, and if iodine is present 
the starch is colored blue. This test is extremely delicate. If 
iodine is found, the cork with the bulb-tube is removed, and the 
solution boiled until, on testing again in the same way, no more 
iodine is found. If much iodine is present, it is necessary to 
add more ferric sulphate solution. The bulb-tube is now 
cleaned, charged with a few drops of water and a drop or two 
of chloroform, and a very small crystal of potassium perman- 
ganate added to the solution in the flask. The contents of the 
flask are boiled again, and if bromine is present the chloroform 
becomes red. The tube is now removed, and more potassium 
permanganate and ferric sulphate added, little by little, the 
mixture being boiled between each addition until the bromine 
lias all been driven off. A few drops of alcohol are added to 
the contents of the flask to decolorize any excess of perman- 
ganate, and after filtration chlorine is tested for in the filtrate 
with silver nitrate. 

Chlorides may also be detected in bromides and iodides by taking 
advantage of the formation of chlorochromic anhydride (p. 240) 
and the non-occurrence of corresponding compounds of bromine 
or iodine, as follows : 

To a solution of a mixture of an iodide with a bromide and 
a chloride add a concentrated solution of sodium sulphite, then 
a reagent prepared by mixing equal volumes of sulphuric acid 
and saturated solution of copper sulphate, until no further pre- 
cipitation of cuprous iodide occurs. Next add solution of soda 
to remove excess of copper sulphate, filter, and evaporate to 
dryness. Transfer the dried residue, together with an equal 
bulk of red potassium chromato, to a dry test-tube fitted with 
a delivery-tube, or to a small retort, and cover the mixture with 
sulphuric acid. Distil into water. Chromic anhydride and 
hydrochloric and hydrobromio acids are liberated by the sul- 
phuric acid, and, reacting one upon another, form chlorochromic 
anhydride, together with free bromine and chlorine. 

Cr0 8 + 2HC1 =- CrCl A + H 2 
2Cr0 8 + 6HBr + 3H 2 SO, Cr 2 3S0 4 -\ 3Br I Oil./) 
2O0, | (illCl + 3H 2 S0 4 - Cr 2 3S0 4 + 3C1 2 -f 6H 2 0. 

13 



278 THE ACIDULOUS RADICALS. 

The chlorochromic anhydride is decomposed by the excess of 
water into which it distils, giving rise to chromic acid, which 
imparts its color to the liquid, and hydrochloric acid, thus : 

CrCl 2 2 + 2H 2 = H 2 O0 4 + 2HC1. 

Chlorine gas escapes, and the bromine is dissolved by the water. 
The colored liquid is then shaken with chloroform, which 
removes the bromine, indicating bromides in the original sub- 
stance. A yellow color remaining is due to chromic acid, indi- 
cating chlorides in the original substance. Or add ammonia to 
the distillate : the color due to bromine is thereby entirely 
removed, while that of the chromic compound is only slightly 
modified. 

Instead of eliminating the iodine as cuprous iodide, it may 
be expelled in vapor, obvious enough by its color and odor, by 
fusing the dry mixture of the salts with excess of powdered 
red chromate. The residue, broken into small fragments, may 
•then be distilled with the sulphuric acid for the detection of 
the bromine and chlorine. 

5K 2 Cr 2 7 + 6KI = 8K 2 O0 4 -f O 2 3 + 3I 2 . 

Fourth Analytical Reaction. — Iodides have been shown to be 
useful in testing for mercuric salts (see the Mercuric Reactions, 
p. 206) ; a mercuric salt (corrosive sublimate, for example) 
may therefore be used in testing for iodides, a scarlet precipi- 
tate (mercuric iodide, Hgl 2 ) being produced. 

This reaction may be employed where large quantities of an 
iodide are present, but its usefulness in analysis is much impaired 
by the fact that the precipitate is soluble in excess of the dissolved 
iodide or in excess of the mercurial reagent. Its color and insolu- 
bility in water distinguish it from mercuric chloride, bromide, and 
cyanide, which are white soluble salts. 

Fifth Analytical Reaction. — Iodides have also (see the Lead 
Reactions, p. 213) been shown to be useful in testing for lead 
salts ; similarly a lead salt (acetate, for example) may be used 
in testing for iodides, in solutions which are either neutral or 
faintly acid with acetic acid, a yellow precipitate (lead iodide, 
Pbl 2 ), soluble in hot water and crystallizing in yellow scales on 
cooling, being produced. 

Lead chloride, bromide, and cyanide are white ; hence the above 
reaction may occasionally be useful in distinguishing iodine from the 
allied radicals. But lead iodide is slightly soluble in cold water ; 
hence small quantities of iodine cannot be detected by this reaction. 
(For Iodates, see Index.) 

Analogies between Chlorine, Bromine, Iodine, and their Compounds. 



CYANIDES. 279 

— These elements form a natural group or family, each distinct 
from the other, yet closely related. Moreover, their dissimilarities 
are so curiously gradational as to irresistibly suggest the idea that 
some day we may find the differences between these bodies to be in 
degree rather than in kind. Thus chlorine is a gas and iodine a 
solid, while bromine occupies the intermediate condition. The 
atomic weight of bromine is nearly midway between those of 
chlorine and iodine. The same may be said of the weight of equal 
volumes of each in a gaseous state. The specific gravity of fluid 
chlorine is 1.33, of iodine 4.95, while bromine is nearly 3. Liquid 
chlorine is transparent, iodine opaque, bromine intermediate. The 
crystalline forms of the chloride, bromide, and iodide of a metal are 
commonly identical. One volume of either element in the gaseous 
state combines with an equal volume of hydrogen (at the same 
temperature) to form two volumes of a gaseous acid, very soluble 
in water (hydrochloric acid, hydrobromic acid, hydriodic acid). 
Many other analogies are traceable. (Vide Index, " Periodic Law.") 



QUESTIONS AND EXERCISES. 

State the method by which bromine is obtained from its natural com- 
pounds — Mention the properties of bromine. — How may potassium and 
ammonium bromides be made?. — By what reagents may bromides be 
distinguished from chlorides? — Whence is iodine obtained? — By what 
process is iodine isolated ? — State the properties of iodine. — What is the 
nature of sulphur iodide?— Give the analytical reactions of iodides. — 
What three substances may indirectly be detected by a mixture of potas- 
sium iodide and mucilage of starch ? — Describe a method by which iodides 
may be removed from a solution containing chlorides and bromides. 



HYDROCYANIC ACID AND OTHER CYANIDES. 

Formula of Hydrocyanic Acid, HCN or HCy. Molecular 
weight, 27. 

History of Cyanogen. — The acidulous radical of hydrocyanic acid 
and other cyanides is a compound body, cyanogen (CN, or, shortly, 
Cy or C 2 N 2 or N=C — C~N). It is so named from Kvavog, kuanos, 
blue, and yewdto, gennao, I generate, in allusion to its prominent 
chemical character of forming, with iron, the different varieties of 
prussian blue. It was from prussian blue that Scheele in 1782 first 
obtained what we now, from our knowledge of its composition, 
term hydrocyanic acid (HCy, or HCN, or H — C=N), but which he 
called prussic acid. Cyanogen was isolated by Gay-Lussac in 1814, 
and was the first compound radical distinctly proved to exist. 

Sources. — Cyanogen does not occur in nature, and is only formed 
from its elements under certain circumstances. It is found in small 
quantities among the gases of iron-furnaces, and is produced to a 
slight extent in distilling coals for gas. In the form of potassium 
ferrocyanide it is obtained abundantly by heating animal refuse 
containing nitrogen, such as the scrapings of horns, hoofs, and hides 



280 • THE ACIDULOUS RADICALS. 

(5 parts), with potassium carbonate (2 parts) and waste iron (filings, 
etc.) in a covered iron pot. The residual mass is boiled with water, 
the mixture filtered, and the filtrate evaporated and set aside for 
crystals to form. The cyanogen, produced from the carbon and 
nitrogen of the animal matter, unites with the potassium, and 
afterward, on boiling with water, with iron, to form what is 
often termed the yellow prussiate of potash, or potassium ferro- 
cyauide, Potassii Ferrocyanidum, U. S. P. (K / 4 Fe // Cy / 6 ,3H 2 0), a 
compound occurring in four-sided tabular yellow crystals. It con- 
tains the elements of cyanogen, yet is not a cyanide, for it is not 
poisonous and is otherwise different from cyanides : it will be further 
noticed subsequently. From this salt all cyanides are directly or 
indirectly prepared. 

Potassium Cyanide (KCy) (Potassii Cyanidum, U. S. P.), the most 
common cyanide, may be obtained by heating the ferrocyanide to 
redness until gas (chiefly nitrogen) ceases to be evolved, and iron 
carbide settles to the bottom of the molten mass of almost pure 
cyanide. The product, carefully poured off and cooled, is an opaque 
crystalline mass containing about 95 per cent, of the salt. It also 
may be procured by fusing 8 parts of potassium ferrocyanide with 
3 of potassium carbonate in a crucible ; carbonic acid gas (C0 2 ) is 
evolved, iron (Fe) is set free, and potassium cyanate (KCyO), a body 
that will be subsequently noticed, is formed at the same time : 

2K 4 FeCy 6 -f 2K 2 C0 3 = lOKCy + 2KCyO + Fe 2 + 2C0 2 . 

Double Cyanides exist, such as sodium and silver cyanide (NaCy,- 
AgCy), formed in the process (subsequently described) of quanti- 
tatively determining the amount of hydrocyanic acid in a liquid by 
a standard solution of silver nitrate : these compounds have more or 
less the properties of their constituents. But other cyanogen com- 
pounds, not double cyanides, occur in which the cyanogen is so 
intimately united with a metal as to form a distinct radical : such 
are ferrocyanides and ferricyanides — salts which will be noticed in 
due course. 

Cyanogen, like chlorine, bromine, and iodine, is univalent (Cy'). 
It may be isolated by simply heating mercuric cyanide (HgCy 2 ) or 
silver cyanide (AgCy). It is a colorless gas, burning, when ignited, 
with a beautiful peach-blossom-colored flame. 

Mercuric cyanide is produced in crystals on dissolving 1 part of 
potassium ferrocyanide in 15 parts of boiling water, adding 2 parts 
of mercuric sulphate, keeping the whole hot for ten or fifteen min- 
utes, and then filtering and setting aside to cool. In addition to 
mercuric cyanide (HgCy 2 ), mercury (Hg), ferric sulphate (Fe 2 3SG\), 
and potassium sulphate (K 2 S0 4 ) are formed. Any excess of ferro- 
cyanide also gives prussian blue by reaction with the ferric sul- 
phate. Hydrargyri Cyanidum, U. S. P., may also be made by dis- 
solving red oxide of mercury in diluted hydrocyanic acid. A small 
flame of cyanogen may be obtained on heating a few crystals of 
mercuric cyanide in a short piece of glass tubing closed at one end, 
and applying a light to the other end as soon as evolution of gas 
commences ; brown paracyanogen (C 3 N 3 ) and mercury remain. 



CYANIDES. 281 

Reactions. 
Diluted Hydrocyanic Acid, or Prussic Acid. 

Synthetical Reaction. — Dissolve 2 or 3 grains of potassium 
ferrocyanide in five or six times its weight of water in a test- 
tube, add a few drops of sulphuric acid and boil the mixture, 
conveying the evolved gas by a bent glass tube (adapted to the 
test-tube by a cork) into another test-tube containing a little 
water; the product is a dilute solution of hydrocyanic acid. 
Made by this process in larger quantities and of a certain defi- 
nite strength (2 per cent.), this solution is the Acidum Hydro- 
cyaniciun Dilutwn, U. S. P., "a colorless liquid of peculiar 
odor. Specific gravity, 0.997." 

2K 4 FeCy 6 + 6H 2 SO, = Fe"K 2 FeCy 6 + 6KHSO, + 6HCy. 

The following are the details of the official (U. S. P.) process : 
Place 20 parts of potassium ferrocyanide in coarse powder in a 
tubulated retort, and add to it (40) parts of water. Connect the 
neck of the retort (which is to be directed upward), by means of a 
bent tube, with a well-cooled condenser, the delivery-tube of which 
terminates in a receiver surrounded with ice-cold water, and con- 
taining 65 parts of distilled water. All the joints of the apparatus, 
except the neck of the receiver, having been made air-tight, pour 
into the retort, through the tubulure, the 8 parts of sulphuric acid, 
previously diluted with 25 parts of water. Agitate the retort gently, * 
and then heat it, in a sand-bath, until the contents are in brisk 
ebullition, and continue the heat regularly until there is but little 
liquid mixed with the saline mass remaining in the retort.* (The 

* This operation is peculiarly liable to those sudden and tumultuous 
evolutions of vapor, or " Dumpings," or " soubresauts," which often inter- 
fere with successful distillation. Such phenomena occur, according to 
Tomlinson, whenever unaided heat has to overcome the great amount of 
adhesion naturally existing between certain liquids and vapors, or, 
rather, between the normal liquid and those particles of it which, be- 
coming strongly heated at the heated part of the vessel, have assumed 
the conditiion of particles of dissolved vapor, and which would at once 
pass from this condition into that of permanent vapor but for adhesion. 
Ordinarily, a glass or other surface is not absolutely clean, but is more or 
less covered, with specks, traces of materials deposited from the air, the 
ringers, cloths, etc. Some liquids seem to have little or no adhesion for 
these materials, while certain vapors have greater adhesion for the films 
than for the liquids. Hence, in ordinary regular ebullition the vapors 
accumulate on the films, and then at once become subject to the pressure 
of the mass of fluid, and so pass off in bubbles. But when the films are 
absent or have become removed during distillation, the heat accumulates 
until it is sufficient to overcome the adhesion of the superheated particles, 
and these are then, all of them at once, converted into vapor, the liquid 
sometimes boiling over or even bursting the vessel. "Bumping" may 
be prevented by using glass vessels roughened inside (by hydrofluoric 
acid or otherwise), or by inserting fragments of substances for which 
vapor-particles have adhesion, but no known substance has this property 
in an absolute degree. Tobacco-pipe or pumice-stone, pieces of cork, 
thick paper, resin, sulphur, platinum wire, etc. are useful when there is 



282 THE ACIDULOUS RADICALS. 

end of the condenser or an attached tube should pass quite into the 
receiver.) Detach the receiver, and add to its contents so much dis- 
tilled water as may be required to bring the product to the strength 
of 2 per cent, of absolute hydrocyanic acid. ( Vide paragraphs on 
quantitative analysis.) 

The residue of this reaction is acid potassium sulphate (KHS0 4 ), 
which remains in solution, and potassium and iron ferrocyanide 
(Fe // K 2 FeCy 6 ), an insoluble powder sometimes termed Everitt's 
yellow salt, from the name of the chemist who first made out the 
nature of the reaction. The latter compound becomes bluish-green 
during the reaction, owing to the absorption of oxygen. 

Another Process. — A 2 per cent, solution may also be made by 
shaking together in a glass-stoppered bottle 6 grms. of silver 
cyanide, 5 cc. of hydrochloric acid, and 35 cc. of distilled water, and 
pouring off the clear liquid. 

Pure anhydrous hydrocyanic acid is a colorless, highly volatile, 
intensely poisonous liquid, solidifying when cooled to a low temper- 
ature.* It may be made by passing sulphuretted hydrogen over 
mercuric cyanide. The official solution of the acid is fairly stable, 
but is said to be rendered more so by the presence of a minute trace 
of sulphuric or hydrochloric acid. A stronger acid is liable to 
assimilate the elements of water and yield ammonium formate 
(NH 4 CH0 2 ). Solutions of hydrocyanic acid often become brown by 
formation of what is, apparently, paracyanogen (C 3 N 3 ). According 
to Williams, aqueous hydrocyanic acid containing 20 per cent, of 
glycerin can be kept for an almost indefinite length of time. The 
official acid should be preserved in well-corked bottles tied over with 
impervious tissue and kept inverted, when not in use, in a cool, 
dark place. Unless such precautions are adopted, the fluid rapidly 
loses strength by escape of the vapor of the acid. 

Note. — A few drops of diluted hydrocyanic acid, so placed that its 
vapor may be inhaled, form the Vapor Acidi Hydrocyanici, B. P., or 
inhalation of hydrocyanic acid. 

Hydrocyanic acid also occurs in cherry-laurel water and bitter- 
almond water. ( Vide Index.) Aqua Laurocerasi, B. P., is made to 
contain 0.1 per cent, of real acid (HCy). 

The methods of determining the strength of hydrocyanic-acid solu- 
tions will be given in connection with volumetric and gravimetric 
quantitative analysis. They are based on the formation of silver 
cyanide and its solubility in solution of alkaline cyanides, as described 
in the next reaction. 

The hydrocyanic acid used in pharmacy is extremely liable to 
variation in strength. It should frequently be tested volumetrically. 

no chemical action between them and the liquid. Tomlinson recom- 
mends cocoanut-shell charcoal. A slow current of gas, such as hydrogen, 
air, or carbonic acid gas, also promotes escape of vapor from a liquid, a 
few capillary tubes, sealed at one end and placed mouth downward in the 
fluid, answering well. A jet of steam prevents bumping, but is not 
always applicable. 

* Traces are formed when electricity passes between carbon poles in 
slightly moist air (Dewar). 



CYANIDES. 283 

Analytical Reactions (Tests). 

First Analytical Reaction. — To a few drops of the hydro- 
cyanic-acid solution produced in the above reaction, or to any 
solution of a cyanide, add excess of solution of silver nitrate ; 
a white precipitate (silver cyanide, AgCy) falls. When the 
precipitate has subsided, pour away the supernatant liquid and 
place half of the residue in another test-tube : to one portion 
add nitric acid, and notice that the precipitate does not dis- 
solve ; to the other add ammonia, and observe that the precipi- 
tate, though soluble, dissolves somewhat slowly. (Silver 
chloride, which is also white, is readily soluble in ammonia.) 
Silver cyanide dissolves in solution of cyanides of alkali-metals, 
soluble double cyanides being formed {e.g. KCyAgCy). 

Solubility of Precipitates in Strong Solutions of Salts. — Silver 
cyanide and many other precipitates insoluble in acids (similar re- 
marks apply to precipitates insoluble in alkalies) are often soluble 
in the saline liquids formed by the addition of acids and alkalies to 
each other. Hence the precaution of adding the latter reagents to 
separate portions of a precipitate, or of not adding the one until the 
other has been poured away. 

Cyanogen in an insoluble cyanide, such as silver cyanide itself, is 
readily recognized on heating the substance in a short piece of glass 
tubing closed at one end like a test-tube and drawn out at the other 
end so as to have but a small opening ; on applying a flame the 
escaping cyanogen ignites and burns with a characteristic peach- 
blossom tint. Metallic silver remains. 

Antidote. 

Second Analytical Reaction. — To a dilute solution of hydro- 
cyanic acid, or a soluble cyanide, add a few drops of solution 
of a ferrous salt and a drop or two of solution of a ferric salt 
(ferrous sulphate and ferric chloride are usually at hand) ; to 
the mixture add potash, soda, magnesia, or sodium carbonate, 
and then hydrochloric acid ; a precipitate of prussian blue 
remains. The decompositions may be traced in the following 
equations : 

HCy + KHO = KCy + H 2 
2KCy + FeS0 4 = FeCy 2 + K 2 S0 4 
4KCy + FeCy 2 = K 4 FeCy 6 or K 4 FCy 
3K 4 Fcy + 2Fe 2 Cl 6 = 12KC1 + Fe,Fcy 3 . 
The test depends on the conversion of the cyanogen into ferro- 
cyanogen by aid of the iron of a ferrous salt and the combination of 
the ferrocyanogen, so produced, with the iron of a ferric salt. 

Hence a mixture of a ferrous sulphide, solution of iron perchloride, 
and either magnesia or sodium carbonate is the recognized antidote 
in cases of poisoning by hydrocyanic acid or potassium cyanide. 



284 THE ACIDULOUS RADICALS. 

In such an alkaline mixture the poisonous cyanide, by reaction 
with ferrous hydrate, is at once converted into innocuous potassium 
or sodium ferrocyanide, etc. : should the mixture become acid, the 
ferric salt present reacts with the soluble ferrocyanide, forming 
insoluble prussian blue, which is also inert. From the rapidity of 
the action of these poisons, however, there is seldom time to prepare 
an antidote. Emetics, the stomach-pump or stomach-siphon, the appli- 
cation of a stream of cold water to the spine, and the above antidote 
form the usual treatment. 

Third Analytical Reaction. — To solution of hydrocyanic acid 
add ammonia and common yellow ammonium sulphydrate, and 
evaporate the liquid nearly or quite to dryness in a small dish, 
occasionally adding ammonia till the excess of ammonium 
sulphydrate is decomposed ; add water and acidify the liquid 
with hydrochloric acid, and then add a drop of solution of a 
ferric salt ; a blood-red solution of iron sulphocyanate will be 
formed. 

This is a very delicate reaction. Some free sulphur in the yellow 
ammonium sulphydrate unites with the alkaline cyanide and forms 
sulphocyanate (2NH 4 Cy -f- S 2 = 2NH 4 CyS) 5 the ammonia combines 
with excess of free sulphur and forms, among other salts, ammo- 
nium sulphydrate, the whole of which is removed by the ebullition. 
If the liquid has not been evaporated far enough, ammonium sul- 
phydrate may still be present, and give black ferrous sulphide on 
the addition of the ferric salt ; hence prior acidification. 

Hydrocyanic Acid in the Blood. — According to Buchner, the 
blood of animals poisoned by hydrocyanic acid, instead of coagulat- 
ing as usual, remains liquid and of a clear cherry-red color for 
several days. In one case he obtained the reactions of the acid on 
diluting and distilling the blood fifteen days after death, and apply- 
ing the usual reagents to the distillate. Aqueous solution of 
hydrogen peroxide changes such blood to a deep-brown color. 

Schonbein' 's test for hydrocyanic acid is said to be extremely deli- 
cate. Filtering-paper is soaked in a solution of 3 parts of guaiacum 
resin in 100 of alcohol. A strip of this paper is dipped in a solution 
of 1 part of copper sulphate in 50 of water ; a little of the suspected 
solution is placed on this paper and exposed to the air, when it 
immediately turns blue. Or the paper may be placed over the neck 
of an open bottle of medicine supposed to contain hydrocyanic acid 
or otherwise exposed to the suspected vapor of the acid. 



QUESTIONS AND EXERCISES. 



Write a paragraph on the history of cyanogen. — Mention the source of 
the cyanogen of cyanides. — How is potassium ferrocyanide prepared ? 
—What is the formula of potassium ferrocyanide ? — Is potassium ferro- 
cyanide poisonous? — Write an equation expressive of the reaction which 
ensues when potassium ferrocyanide and carbonate are brought together 
at a high temperature. — What are the properties of cyanogen ? — How 



NITRATES. 285 

may it be obtained in a pure condition ?— How is mercuric cyanide pre- 
pared ?— What other substances and secondary products are formed at 
the same time? — How much real hydrocyanic acid is contained in the 
official Aciclum Hydrocyanicum Diliitum? — Give details of the preparation 
of hydrocyanic acid and an equation of the reaction. — State the propor- 
tion of water that must be added to an aqueous solution containing 15 
per cent, of hydt-ocyanic acid to reduce the strength to 2 per cent. Ans. 
62 to 1. — What are the characters of pure undiluted hydrocyanic acid ? — 
How may it be obtained? — Enumerate the tests for cyanogen, giving 
equations. — Explain the action of the best antidote in cases of poisoning 
by hydrocyanic acid or potassium cyanide.— Show how it acts in alkaline 
and acid solutions respectively. 



NITRIC ACID AND OTHER NITRATES. 

Formula of the acid, HN0 3 or HON0 2 . Molecular weight, 63. 

Introduction.— -The group of elements represented by the formula 
N0 3 is that characteristic of nitric acid and all other nitrates ; hence 
it is expedient to regard these elements as forming an acidulous 
radical, which may be termed the 7iitric radical. Like the hypothet- 
ical basylous radical ammonium (NH 4 ), this supposed acidulous 
radical (N0 3 ) has not been isolated. Possibly it is liberated when 
chlorine is brought into contact with silver nitrate ; but if so, its 
decomposition into white crystalline nitric anhydride (N 2 5 ) and 
oxygen (0) is too rapid to admit of its identification. 

Sources. — The nitrogen and oxygen of the air combine and ulti- 
mately form nitric acid whenever a current of electricity (as in the 
occurrence of lightning) passes. The nitrates found in rain may 
partly or wholly thus originate. The oxidation of ammoniacai 
matter and of the nitrogenous constituents of animal and vegetable 
matters in the soil, favored by the darkness, by the occurrence of 
calcium carbonate, and by the presence of some low form of vege- 
table life acting as a ferment, results in the production of nitrates. 
Hence nitrates are commonly met with in waters, soils, and the 
juices of plants. In the concentrated plant-juices, termed medicinal 
" Extracts," small prismatic crystals of potassium nitrate may occa- 
sionally be observed. (The cubical crystals often met with in 
extracts are potassium chloride.) Nitric acid and other nitrates are 
obtained from potassium and sodium nitrates, and these from the 
surface layers of the soil of tropical countries. Potassium nitrate, 
or prismatic nitre (from the form of its crystals), is chiefly produced 
in and about the villages of India. The natives simply scrape the 
surface of waste grounds, mud-heaps, banks, and other spots where 
a slight incrustation indicates the presence of appreciable quantities 
of nitre, mix the scrapings with wood-ashes (potassium carbonate, to 
decompose the calcium nitrate always present), digest the mixture 
in water, and evaporate the liquor. The immediate product is puri- 
fied by careful recrystallizations, and is sent into commerce in the 
form of white crystalline masses or fragments of striated six-sided 
prisms. Besides its use in medicine (Potassii Kitras, IL S. P., 
Nitrate of Potassium, or Potassium Nitrate), it is employed in very 
13* 



286 THE ACIDULOUS RADICALS. 

large quantities in the manufacture of gunpowder. Oharta Potassii 
Nitratis, U. S. P., Nitrate-of-Potassium Paper, is made by dipping 
strips of white unsized paper in a solution of 1 part of the salt in 4 
parts of water and drying them. Sodium Nitrate (Sodii Nitras, 
U. S. P.), the old nitrate of soda, occurs in deposits from three inches 
to three yards in thickness on and near the surface, and at any 
depth down to about thirty feet, in many parts of Peru, Bolivia, and 
Chili, but more especially in the district of Atacama. The mineral 
is termed caliche, and commonly contains 50 per cent, of sodium 
nitrate. The latter is distinguished as Chili saltpetre or Chili nitre, 
or (from the form of its crystals — obtuse rhomboids, not true cubes) 
cubic nitre, and is chiefly used as a manure and as a source of nitric 
acid, its tendency to absorb moisture unfitting it for use in gun- 
powder. In many parts of Europe potassium nitrate is made arti- 
ficially by exposing heaps of animal manure, refuse, ashes, and soil 
to the action of the air and the heat of the sun ; in the course of a 
year or two the nitrogen of the animal matter becomes oxidized to 
nitrates ; the latter are removed by washing. According to Waring- 
ton, the nitrifying ferment appears capable of existing in three con- 
ditions : (1) The nitric ferment of soil, which converts both ammo- 
nium salts and nitrites into nitrates ; (2) the altered ferment, which 
converts ammonium salts into nitrites, but fails to change nitrites 
into nitrates ; and (3) the surface organism (a bacterium) which 
changes nitrites into nitrates. Similar nitrification goes on in 
impure well and river waters, which thereby tend to become pure. 

Note. — The word nitric is from nitre, the English equivalent of 
the Greek vlrpov (nitron), a name applied to certain natural deposits 
of natron (sodium carbonate), for which potassium nitrate seems at 
first to have been mistaken. Saltpetre is simply sal petros, salt of 
the rock, in allusion to the natural origin of potassium nitrate. Sal 
prunella (from sal, a salt, and pruna, a live coal) is potassium 
nitrate melted over a fire and cast into cakes or bullets. 

The nitric radical is univalent (N0 3 / ). 

Constitution of Salts. 
It is here necessary again to caution the reader against regarding 
salts as invariably possessing a known constitution, or supposing 
that they always possess two or more sides or contain definite radi- 
cals. The erroneous conception which, of all others, is most likely 
to be imperceptibly formed is that of considering salts to be binary 
bodies. For, first, the names of salts are necessarily binary. A 
student hears the names " iron sulphate," " copper sulphate," and 
simultaneously receives the impression that each salt has two sides, 
copper or iron occupying one, and something indicated by the word 
" sulphate" the other. Such words as "vitriol," green or blue, or 
"nitre," would perhaps implant unitary ideas in the mind, but it 
is simply impossible to give such names to all salts as will convey 
the impression that each salt is a whole, and therefore unitary. 
The name " sulphate of potash" produces binary impressions, and 
the less incorrect name, "sulphate of potassium" or "potassium 
sulphate," is in this respect no better. Secondly, it is impracticable 



NITRATES. 287 

to study salts as a whole. Teachers are almost unanimous in the 
opinion that students should first master the reactions characteristic 
of the metals in salts, and then the residues which, with those 
metals, make up the salts, and vice versa. It is not only impracti- 
cable, but impossible, to study salts as a whole ; binary ideas con- 
cerning them are therefore almost inevitably imbibed. We come 
to regard a salt as a body which splits up in one direction only : 
look upon nitre, for instance, and all other nitrates, as containing 
N0 3 and a metal, M ; whereas KN0 3 may be split up into KN0 2 
and 0, or into K 2 0,N 2 , and 5 , or may contain K 2 and N 2 5 . 
These are the chief disadvantages attending the employment of the 
binary hypothesis in studying chemical compounds : if they be 
borne in mind, the hypothesis may be freely used without much 
danger of permanent mental bias. Thus, in nitre let the group of 
elements (N0 3 ) which, with potassium, makes up the whole salt, be 
called the nitric radical, the name of the latter being directly derived 
from its hydrogen salt. Similarly, allow the acidulous residues of 
other salts of metals to be termed respectively the chloric, acetic, 
sulphurous, sulphuric, carbonic, oxalic, tartaric, phosphoric, citric, 
boracic radicals. In short, these compound radicals should be 
regarded as groupings common to many salts, and which may 
usually be transferred without any apparent breaking or splitting ; 
at the same time we must be prepared to find that occasionally a 
salt divides in other directions. In this way perhaps erroneous 
impressions will gain least hold on the mind, and a way be left 
open for the easy entrance of new truths should the real constitution 
of* salts be discovered. 

Formerly, salts (such as magnesium sulphate) were regarded as 
containing (a) an oxide of a metal (MgO) and an anhydride (S0 3 ), 
the latter being incorrectly called an acid (sulphuric acid) ; or (b) 
as containing two simple radicals (e.g. KI,NaCl,KCy,HgS) — the 
former being called oxyacid salts or oxysalts, and the latter haloid 
salts (from alg, als, sea-salt, and eldog, eidos, likeness). Such dis- 
tinction is no longer maintained, the two classes being merged. 
This is an important educational gain on the side of simplicity ; for 
whereas under the old system much time was necessarily expended 
before salts of a metal and salts of the oxide of that metal could be 
distinguished (e.g. KI and K 2 0,S0 3 ), now, all salts being regarded 
as salts of the metals themselves (e.g. KI and K 2 S0 4 ), no such 
distinction is necessary. 

Reactions. 

Nitric Acid. 

Synonyms. — Hydrogen Nitrate ; Nitrate of Hydrogen. 

Synthetical Reaction. — To a fragment of potassium nitrate or 
sodium nitrate in a test-tube add a drop or two of sulphuric 
acid, and warm ; nitric acid (HN0 3 ) is evolved in vapor. The 
fumes may be condensed by a bent tube fitted to the test-tube 
not by a cork, as for hydrochloric acid— because the nitric 



288 THE ACIDULOUS RADICALS. 

vapors would strongly act on it — but by plaster of Paris, a 
paste of which sets hard on being put aside for a short time 
and is unaffected by the acid. 

On a somewhat larger scale nitric acid may be prepared by 
heating, in a stoppered or plain retort, a mixture of equal 
weights of potassium nitrate and sulphuric acid ; the acid dis- 
tils over, and acid potassium sulphate remains behind : 
KN0 3 + H 2 S0 4 = HN0 3 + KHSO, 

Potassium Sulphuric Nitric Acid potassium 

nitrate. acid. acid. sulphate. 

Half the quantity of sulphuric acid may be taken ; but in that 
case neutral potassium sulphate (K 2 S0 4 ) is produced, which, from 
its hard, slightly soluble character, is removed with difficulty from 
the retort. On the manufacturing scale the lesser proportion is 
used, but instead of retorts iron cylinders are employed, from which 
the residual salt is removed by chisels. Moreover, the cheaper 
sodium salt is the nitrate from which manufacturers usually prepare 
nitric acid, 7 parts of sodium nitrate and 4 of sulphuric acid being 
employed. 

Note. — The acid potassium sulphate is readily converted into neu- 
tral sulphate (Potassii Sulphas, Sulphate of Potassium, or Potassium 
Sulphate, U. S. P.) by dissolving in water, adding potassium car- 
bonate until effervescence ceases to occur, filtering, and setting aside 
to crystallize. 

Pure nitric acid (HN0 3 ) is a colorless liquid, somewhat difficult 
of preparation; its specific gravity is 1.52. The strongest acid met 
with in commerce has a sp. gr. of 1.5, and contains 93 per cent, of 
real nitric acid (HN0 3 ) ; it fumes disagreeably, is unstable, and, 
except as an escharotic, is seldom used. The United States Phar- 
macopoeia contains two acids: Acidum Nitricum, of sp. gr. 1.414 
and containing 68 per cent, of real acid (HN0 3 ) ; and another, 
Acidum Nitricum Dilutum, sp. gr. 1.057, containing 10 per cent. 
The stronger liquid, although containing water, is usually simply 
termed "nitric acid." The official nitric acid, of sp. gr. 1.414, is a 
definite hydrous acid (2HN0 3 ,3H 2 0) 5 it distils at 240° F. without 
change. If a weaker acid be heated, it loses water ; if a stronger 
acid be heated, it loses nitric acid until the density of 1.42 is reached. 
Aquafortis is an old name for nitric acid {Aqua Fortis Simplex, sp. 
gr. 1.22 to 1.25 ; Aqua Fortis Duplex, 1.36). The strength of a 
specimen of nitric acid is determined by volumetric analysis. Nitric 
Anhydride (N 2 5 ), sometimes but erroneously called Anhydrous 
Nitric Acid, is a solid crystalline substance formed on passing dry 
chlorine over dry silver nitrate. 

Metals reduce nitric acid to nitrous acid and to the various oxides 
of nitrogen, or even to nitrogen itself, according to the strength of 
acid, temperature, and amount of nitrate present. Not infrequently 
ammonium nitrate is simultaneously formed. Thus with zinc : 

IOHNO3 + 2Zn 2 = 4(Zn2N0 3 ) + NH 4 N0 3 + 3H 2 0. 

Aqua Regia, or Nitrohydrochloric Acid. — 2 parts of nitric acid 



NITRATES. 289 

and 9 of hydrochloric acid by volume form the Acidum Nitrohydrochlo- 
ricum, U. S. P., and the same weights, with 78 of water, give the 
Acidum Nitrohydrochloricum Dihiium. The mixture should be set 
aside for a week in summer or a fortnight in winter to ensure 
mutual decomposition and full development of the -chief active prod- 
uct, chlorine : 

2HN0 3 + 6HC1 = N 2 2 C1 4 ? + 4H 2 + CL. 

Nitric acid. Hydrochloric acid. Chloronitric gas. Water. Chlorine. 

In the latter stages of the reaction the decomposition expressed in 
the following equation also probably occurs : 
HN0 3 4- 3HC1 == NOC1 + 2H 2 + Cl 2 . 

Nitric acid. Hydrochloric acid. Chloronitrous gas. Water. Chlorine. 

The undiluted mixture of acids is known as aqua regia, from its 
property of dissolving gold, the "king of metals." 

" Diluted nitrohydrochloric acid " may attack organic matter with 
evolution of nitrous gases, hence should not be dispensed with 
tinctures, etc. without further dilution. 

Analytical Reactions (Tests). 

First Analytical Reaction. — To a solution of any nitrate (e. g. 
KNO3) add sulphuric acid, and then copper turnings, and 
warm ; colorless nitric oxide gas (NO) is evolved, which at 
once unites with the oxygen in the tube, giving real fumes of 
nitric peroxide or nitrogen peroxide (N0 2 ). 
2KN0 3 4- 5H 2 S0 4 + Cu 3 = 2NO -f 3CuSO. 4- 4H 2 4- 2KHS0 4 : 
then 2NO 4- 2 = 2N0 2 . 

Performed on a larger scale in a vessel to which a delivery-tube 
is attached, the reaction of nitric acid on copper becomes of syn- 
thetical interest, being the process for the preparation of nitric 
oxide gas for the purposes of chemical experiment. 

Small amounts of a nitrate may be overlooked by this test, the 
color of the red fumes not being very intense. 

Undiluted nitric acid poured on to copper turnings gives dense 
red vapors of nitrous acid (HN0 2 ), nitrous anhydride (N 2 3 ), nitric 
peroxide (N0 2 ), nitric oxide (NO), and even nitrogen (N 2 ), the reac- 
tion varying somewhat according to the temperature of the mixture 
and (Ackworth) the amount of copper nitrate in solution. With 
ordinary copper diluted nitric acid gives nitric oxide, Cu 3 -\- 8HNO, 
= 3(Cu2N0 3 ) 4- 4H 2 4- 2NO. 

Second Analytical Reaction. — To a cold solution of a nitrate, 
even if very dilute, add three or four crystals of ferrous sul- 
phate, shake gently for a minute, in order that some of the 
sulphate may become dissolved, and then pour 8 or 10 drops 
•of strong sulphuric acid down the side of the test-tube, so that 
it may form a layer at the bottom of the vessel ; a reddish- 
purple or black coloration will appear between the acid and the 
supernatant liquid. 



290 



THE ACIDULOUS RADICALS. 



This is a very delicate test for the presence of nitrates. Nitrites 
give the reaction without the sulphuric acid. The black color is due 
to a solution, or perhaps combination of nitric oxide with a portion 
of the ferrous salt. The nitric oxide is liberated from the nitrate by 
the reducing action of the hydrogen of the sulphuric acid, the sul- 
phuric radical of which is absorbed by another portion of the ferrous 
sulphate, the latter then becoming ferric sulphate. 

2HN0 3 + 3H 2 SO, + 6FeS0 4 = 4H 2 + 3(Fe 2 3S0 4 ) + 2NO. 

The process of oxidation is one frequently employed in experi- 
mental chemistry, and nitrates, from their richness in oxygen, but 
more especially because always at hand, are the oxidizers usually 
selected for the purpose. In the operation they generally split up in 
one way — namely, into oxide of their basylous radical, nitric oxide 
gas, and available oxygen. Thus hydrogen nitrate (nitric acid) 
commonly yields hydrogen oxide (water) and the other bodies men- 
tioned, as shown in the following equation : 

4HN0 3 = 2H 2 + 4NO -f 30 2 . 

When nitrates, other than nitric acid, are used for the purpose of 
oxidation, a stronger acid, generally sulphuric, is commonly added 
in order that nitric acid may be formed, the hydrogen nitrate split- 
ting up more readily than any other nitrates. 

The jive oxides of nitrogen have now been mentioned — namely : 

N„0 

Nitric oxide * NO 

Nitrous anhydride N 2 3 

Nitric peroxide* N0 2 

Nitric anhydride N 2 5 

Nitrous oxide is a colorless gas, not altered on exposure to air ; 
nitric oxide is also colorless, but gives red fumes in the air •, nitrous 
anhydride is a red vapor condensible to a blue liquid -, nitric peroxide 
is a red vapor condensible to an orange liquid ; nitric anhydride is a 
colorless crystalline solid. The two anhydrides, by absorbing water, 
yield respectively nitrous acid (HN0 2 ) and nitric acid (HN0 3 ). 
Nitrous oxide is also probably an anhydride, the acid of which would 
doubtless have the formula HNO, while the silver and sodium salts 
certainly have the formula AgNO and NaNO,3H 2 (Divers; 
Menke). The above series of compounds forms a good illustration 
of the doctrine of multiple proportions (p 49). 

Third Analytical Reaction. — Direct the blowpipe flame on to 
charcoal until a spot is red hot ; now place on the spot a frag- 
ment of a nitrate ; deflagration ensues. 

This reaction does not distinguish nitrates from chlorates. It is 
sufficient for the recognition of very small quantities of either class 
of salts (especially when they are mixed with other substances). 

* The specific gravities of these gases indicate that NO and NO2 are 
the correct formulae, and not N2O2 and N2O4. 



N 2 2 

NA 

N 9 4 
N.,0, 



J 



NITRATES. 291 

Gunpowder is an intimate mechanical mixture of 75 parts of nitre, 
15 to 12| parts of charcoal, and 10 to 12£ parts of sulphur. In 
burning it may be said to give potassium sulphide (the white smoke, 
K 2 S), nitrogen (N), carbonic oxide (CO), and carbonic acid (C0 2 ) 
gases, though the decomposition is seldom complete. The sudden 
production of a large quantity of highly heated gas from a small 
quantity of a cold solid is sufficient to account for all the effects of 
gunpowder. 

Fourth Analytical Reaction. — To nitric acid or other nitrate 
add solution of " indigo sulphate ; " the color (indigotin-disul- 
phonic acid, C 16 H 8 (HS0 3 ) 2 N 2 2 ) is discharged. 

Indigo Test-solution, U. S. P. (Sulphindylic or Sulphindigotic 
Acid), is made by digesting 1 part of dry finely-powdered indigo in 
6 parts of strong sulphuric acid in a test-tube ; set the mixture 
aside for two days ; the blue liquid is then poured into 25 parts of 
water, the whole well shaken, set aside, and the clear liquid decanted. 
Free chlorine also destroys the color of this reagent. 

Indigo, U. S. P. (C 16 H 10 N 2 O 2 ), is a blue coloring-matter deposited 
when infusion of various species of Indigofera is exposed to air and 
slight warmth. Under these circumstances, indican, a yellow, 
transparent, amorphous substance, soluble in water, breaks up into 
indigo, which is insoluble and falls as a sediment, and a sort of 
sugar termed indiglucin. The indigo is collected, drained, pressed, 
and dried. By action of deoxidizing agents indigo is converted into 
soluble colorless indigogen, reduced indigo, or indigo white ; 1 part 
of powdered indigo, 2 of ferrous sulphate, 3 of slaked lime, and 200 
of water, shaken together and set aside in a well-closed bottle, give 
this colorless indigo (C 16 H 12 N 2 2 ). A piece of yarn, calico, or similar 
fabric dipped into such a solution and exposed to air becomes dyed 
blue, deposition of insoluble indigo-blue occurring within the cells 
and vessels of the fibre. This operation is readily performed on the 
small scale, and forms an illustration of a characteristic feature of 
the art of dyeing — namely, the introduction of soluble coloring- 
matter into a fabric by permeation of the walls of its cellular and 
vascular tissue, and the imprisonment of that coloring-matter within 
the cells and vessels by conversion into a solid and insoluble form. 
( Vide also p. 140.) Indigo is probably a derivative of benzene. 

Pure indigo, or indigotin, may be obtained in beautiful needles by 
spreading a paste of indigo and plaster of Paris on a tin plate, and 
when quite dry placing a lamp underneath, moving the latter from 
place to place as the indigo sublimes and condenses on the surface 
of the plaster. It may also be obtained in crystals by gently boiling 
finely-powdered indigo with aniline, filtering while hot, and setting 
aside ; these crystals may be washed with alcohol. Hot paraffin 
may be employed instead of aniline. Indigo may be produced arti- 
ficially. Toluene, from coal-tar, is by Perkin's process converted 
into cinnamic acid, this into a nitro-derivative, and this again into 
orthonitrophenylpropiolic acid. From the latter alkali and grape- 
sugar deposit crystalline indigo (Baeyer). 

Distinction between Nitric Acid and Other Nitrates. — Presence of 



292 THE ACIDULOUS RADICALS. 

the nitric radical in a solution having been proved by the above re- 
actions, its occurrence as the nitrate of a metal is demonstrated by 
the neutral or nearly neutral deportment of the liquid with test- 
paper and the detection of the metal — its occurrence as nitric acid 
by the sourness of the liquid to the taste and the strong effervescence 
produced on the addition of a carbonate. 

Antidote. — In cases of poisoning by strong nitric acid solution of 
sodium carbonate (common washing soda) or magnesia and water 
may be administered as an antidote. 



QUESTIONS AND EXEECISES. 

Trace the origin of nitrates. — In what does cubic nitre differ from 
prismatic nitre? — Describe a process by which potassium nitrate may be 
obtained artificially. — State the difference between potassium nitrate, 
nitre, saltpetre, and sal prunella. — What group of elements is characteristic 
of all nitrates ? and what claim has this group to the title of radical ? — 
Mention the usual theory regarding the manner in which atoms are 
arranged in reference to each other in such salts as potassium nitrate.— 
How is the official nitric acid prepared ? — Give the properties of nitric 
acid. — What reactions occur when strong nitric and hydrochloric acids 
are mixed? — How is nitric oxide prepared ? — Enumerate and explain the 
tests for nitrates ? — Into what substances does nitric acid usually split 
when employed as an oxidizing agent? — How is nitrous oxide prepared? 
Enumerate the five oxides of nitrogen. — What is the nature of gun- 
powder? — Write a few sentences on the chemistry of indigo, one of the 
tests for nitric acid. — How is nitric acid distinguished from other 
nitrates ? — What quantity of cubic nitre will be required to produce ten 
carboys of official nitric acid, each containing 114 lbs. ? Ans. 10761 lbs. 



CHLORIC ACID AND OTHER CHLORATES. 

Formula of the acid, HC10 3 or C10 2 OH. Molecular weight, 
84.5. Chlorates (p. 293) are made from hypochlorites. 

Hypochlorous Acid (HCIO or ClOH) and other Hypochlorites. 

Place a few grains of red mercury oxide in a test-tube, half 
fill the tube with chlorine-water, and well shake the mixture ; 
the resulting liquid is a solution of hypochlorous acid, mercuric 
oxychloride remaining undissolved : 

2HgO + 2C1 2 + H 2 = 2HC10 + Hg 2 OCl 2 . 

By the metathesis (double decomposition) of hypochlorous 
acid and oxides of hydrates other pure hypochlorites are 
formed : HCIO + NaHO = NaCIO 4- H 2 0. 

The direct action of chlorine on metallic hydrates and some 
carbonates is supposed to give a compound of chloride and 
hypochlorite, as described in connection with the synthetical 



CHLORATES. 



293 



reactions of calcium (p. 114, Calx (7M?rata, U. S. P.). (See 
also p. 87, Liquor Sodse, Chloratse, U. S. P.) 

Cl 2 + 2NaHO =NaCl,NaC10 + H 2 ; 
2C1 2 + 2CaH 2 2 = CaCl 2 ,Ca2ClO -f- 2H 2 0. 

The condition of the chlorine in these bodies is not satisfac- 
torily made out, so that their constitution is not definitely 
determined. The action of acids on them results in the evolu- 
tion of chlorine ; hence the great value of the calcium com- 
pound (chlorinated lime, or chloride of lime) in bleaching 
operations : 

CaCl 2 ,Ca2C10 + 2H 2 SO, = 2C1 2 + 2CaS0 4 + 2H 2 0. 

The solubility of hypochlorites in water, their peculiar odor, 
greatly intensified on the addition of acid, and their bleaching 
powers (see the above calcium reaction) are the characters on 
which to rely in searching for hypochlorites. 

Chlorates. 

The group of elementary atoms represented by the formula C10 3 
is that characteristic of chloric acid and all other chlorates ; hence 
it is expedient to regard it as being an acidulous radical, which may 
be termed the chloric radical. Like the nitric radical, it has not 
been isolated. Chloric anhydride (C1 2 5 ), unlike nitric anhydride, 
has not yet been obtained in the free condition. 

Chlorates are artificial salts. They are formed by simply boiling 
aqueous solutions of the common bleaching salts (chlorinated lime, 
chlorinated soda, chlorinated potash). Heat thus converts 



3(NaCl,NaC10) ) 

Chlorinated 

soda. J 


into 


\ NaClO.3 
1 Sodium 
L chlorate. 


} 


and 


J 5NaCl 

Sodium 
(. chloride. 


3(KC1,KC10) ) 

Chlorinated 

potash. J 


into 


f KC10 3 

1 Potassium 
L chlorate. 


! 


and 


f 5KC1 

-s Potassium 
( chloride. 


3(CaCl 2 ,Ca2C10) ] 

Chlorinated 

lime. J 


into 


f Ca2C10 3 

1 Calcium 
I chlorate. 


1 


and 


f 5CaCl 2 

"j Calcium 
I chloride. 



One chlorate may also be made from another by double decomposition. 
In making chlorates economically the chlorinated salt is, of course, 
at once converted into chlorate. 



, Potassium Chlorate. 

Thus, Potassium Chlorate (Potassii Chlo7'as, or Chlorate of 
Potassium, U. S. P.), the old chlorate of potash, is commer- 
cially made by saturating with chlorine gas a moistened mix- 
ture of 3 parts of potassium chloride and 10 of slaked lime, 
and well boiling the product. Chlorinated lime is first formed ; 



294 THE ACIDULOUS RADICALS. 

this, on continued boiling with water, splits up into calcium 
chloride and calcium chlorate ; and the latter, reacting on the 
potassium chloride, yields calcium chloride and potassium 
chlorate. 

6(Ca2HO) 4 6C1 2 = 3(CaCl 2 ,Ca2C10) + 6H 2 ; 

3(CaCl 2 ,Ca2C10) = Ca2C10 3 4 5CaCl 2 ; 

Ca2C10 3 + 2KC1 = CaCl 2 + 2KC10 3 . 

The operation may be conducted on a small scale by rubbing 
together in a mortar the above proportions of ingredients in 
ounces or half ounces, adding enough water to make the whole 
assume the character of damp lumps, placing the porous mass 
in a funnel (loosely plugged with stones or pieces of glass), 
and passing chlorine gas (p. 29) up through the mass by 
attaching the tube delivering the gas to the neck of the fun- 
nel. When the whole mass has become of a slight pink tint 
(due to a trace of permanganate), it should be turned into a 
dish, well boiled with water, filtered, the filtrate evaporated if 
necessary, and set aside ; the potassium chlorate crystallizes 
out in colorless rhomboidal plates, calcium chloride remaining 
in the mother-liquor. 

In the official process potassium carbonate is alluded to as being 
used in place of chloride, but otherwise the method is similar to 
that just described. Chlorinated potash and chlorinated lime are 
first formed : 

K 2 C0 3 -f Ca2HO + Cl 2 = KC1,KC10 + CaC0 3 + H 2 

6(Ca2HO) 4- 6C1 2 = 3(CaCl 2 ,Ca2C10) + ' 6H 2 0. 
These on boiling with water split up into chlorates and chlorides : 

3(KC1,KC10) = KC10 3 + 5KC1 

3(CaCl 2 ,Ca2C10) = Ca2C10 3 + 5CaCJ 2 , 

the whole of the potassium chloride and calcium chlorate finally 
yielding potassium chlorate and calcium chloride : 

2KC1 + Ca2C10 3 = CaCl 2 + 2KC10 3 . 

Neglecting intermediate decompositions, the reactions may be repre- 
sented by the following equation : 

6C1 2 + K 2 C0 3 4- 6CaH 2 2 = 

Chlorine. Potassium carbonate. Calcium hydrate. 

2KC10., 4- CaCO, 4- 5CaCl 2 -f 6H 2 

Potassium Calcium Calcium Water, 

chlorate. carbonate. chloride. 

Sodium Chlorate (Sodii C Moras, CMorate of Sodium, U. S. P.), 
NaC10 3 , is similarly prepared. 

Potassium chlorate is soluble in water to the extent of 6 or 7 
parts in 100 at common temperatures. It is usually administered 
medicinally in aqueous solution, sometimes also in lozenges [Tro- 



CHLORATES. 295 

chisci Potassii Chloratis, U. S. P.). Potassium chlorate must on no 
account be rubbed with sulphur or sulphides in a mortar or other- 
•wise, friction of such a mixture resulting in violent explosion. 

Potassium chlorate, when heated, yields potassium chloride and 
oxygen, and is the salt commonly employed in the preparation of 
the gas for experimental purposes. But if the action be carried on 
at as low a temperature as possible, and be arrested when 100 parts 
of the chlorate have (Teed) yielded 7.84 parts of oxygen, the residual 
salt will be found to contain only potassium perchlorate (KC10 4 ) 
and chloride : 10KClO 3 = 6KC10 4 + 4KC1 + 30 2 . A higher tem- 
perature causes the decomposition of the perchlorate : KC10 4 = 
KC1 4- 20 2 . When the chlorate is heated with manganese peroxide 
no perchlorate is formed. 

Perchloric Acid (HC10 4 ). — Crude potassium perchlorate, obtained 
as just indicated, is boiled (in a fume-cupboard) with hydrochloric 
acid to decompose any chlorate that may be remaining, and then 
separated from chloride by washing and crystallization, chloride 
being far more soluble in water than perchlorate. Perchloric acid 
is then obtained by distilling the potassium perchlorate with sul- 
phuric acid 5 it is stable, and is occasionally administered in 
medicine. 

Chloric acid (HC10 3 ) may be isolated, but is unstable, quickly 
decomposing into chlorine, oxygen, and perchloric acid ; some other 
chlorate (e. g. KC10 3 ) must therefore be used in studying the reac- 
tions of the chloric radical. 

Table of the Chlorine Acids. 

Hydrochloric acid HOI. 

Hypochlorous acid HCIO. 

Chlorous acid HC10 2 . 

Chloric acid _ HC10 3 . 

Perchloric acid HC10 4 . 

The chloric radical is univalent (CIO/). The acidulous radicals 
of the other chlorine acids are also univalent, as indicated in the 
foregoing formulae. 

Analytical Reactions (Tests). 

First Analytical Reaction. — To solution of a chlorate (e. g. 
potassium chlorate) add solution of silver nitrate ; no precip- 
itate falls, showing that the chlorine must be performing differ- 
ent functions from those it possesses in chlorides. Evaporate 
the solution to dryness and place the residue in a small dry 
test-tube, or at once drop a fragment of a chlorate into a test- 
tube and heat strongly ; oxygen is evolved, and may be recog- 
nized by its power of reinflaming an incandescent match inserted 
in the tube. Boil the residue with water, and again add solu- 
tion of silver nitrate ; a white precipitate falls having all the 



296 THE ACIDULOUS RADICALS. 

characters of silver chloride, as described under Hydrochloric 
Acid. 

Second Analytical Reaction. — To a fragment of a chlorate 
add two or three drops of strong sulphuric acid ; an explosive 
gas (C1 2 4 ) is evolved, somewhat resembling chlorine in odor, 
but possessing a deeper color than that element. 

3KC10 3 + H 2 S0 4 = C1 2 4 + KCIO, -f K 2 S0 4 + H 2 0. 

Warm the upper part of the test-tube to 150° or 200° F., or 
introduce a hot wire ; a sharp explosion ensues, due to decom- 
position of the gas, chlorine peroxide, into its elements. 

Third Analytical Reaction. — Heat a small fragment of a 
chlorate with hydrochloric acid ; a yellowish-green explosive 
gas, termed euchlorine, is evolved. Its color is deeper than 
that of chlorine ; hence the name (from su, eu, well, and 
%Aiopd?, chloros, green). In odor it resembles chlorine, and 
is probably a mixture of that element with one of the oxides 
of chlorine. 

Fourth Analytical Reaction. — Direct the blowpipe flame on 
to charcoal until a spot is red hot, and then place on the spot 
a fragment of a chlorate ; deflagration ensues, as with nitrates. 

Bromates. 

Bromates are salts closely resembling chlorates and iodates. The 
formula of bromic acid is HBr0 3 . The presence of bromates in 
bromides is shown by the production of a yellow color on the 
addition of diluted sulphuric acid. 

5KBr -f- KBrO s + 3H 2 S0 4 = 3K 2 S0 4 + 3H 2 + 3Br 2 . 

Iodates. 

Iodic Acid (HI0 3 ), or Hydrogen Iodate. — Iodine is warmed in a 
flask with five times its weight of the strongest nitric acid (sp. gr. 
1.5), in a fume-cupboard, until all action ceases. On cooling, iodic 
acid separates in small pyramidal crystals. These are removed, the 
residual liquid evaporated to dryness to remove excess of nitric acid, 
the residue and the first crop dissolved in a small quantity of boiling 
water, and the solution set aside to crystallize. Neutralized with 
carbonates or hydrates, it yields iodates. 

Potassium iodate and sulphurous acid decompose each other with 
elimination of iodine (or with formation of a blue color if starch be 
present). Sulphurous acid occurring as an impurity in acetic and 
other acids may thus be detected. 

2KI0 3 + 5H 2 S0 3 = I 2 + 3H 2 S0 4 + 2KHS0 4 + H 2 0. 

Ferric Iodate, or rather Oxyiodate (Fe 2 04I0 3 ,8H 2 0), is pre- 
cipitated on adding solution of ferric chloride to solution of potas- 
sium iodate. 



ACETATES. 297 

QUESTIONS AND EXERCISES. 

How may hypocklorous acid be formed ? — What are the relations of 
hypochlorous acid to bleaching-powder ? — By what reaction is chlorine 
eliminated from hypochlorites? — State the general reaction by which 
chlorates are formed. — Give details of the preparation of potassium 
chlorate. — Mention the properties of potassium chlorate. — What decom- 
positions occur when potassium chlorate is heated ? — Find the molecular 
weight of potassium chlorate. — What weight of oxygen is yielded when 
1 oz. of potassium chlorate is completely decomposed ? and how much 
potassium chloride remains ? — 100 cubic inches of oxygen, at 60° F. and 
barometer at 30 inches, weighing 34.203 grains, and 1 gallon containing 
277i cubic inches, what weight of potassium chlorate will be required to 
yield 10 gallons of the gas? — Ans. 5$ oz. — How many cubic inches of 
oxygen are producible from 1 oz. of potassium chlorate? — Calculate the 
weight of potassium chlorate theoretically obtainable from 100 parts of 
chloride.— How is perchloric acid prepared?— "Enumerate the chlorine 
acids. — How may the presence of chlorides in chlorates be demonstrated ? 
— Mention the tests for chlorates. — Give the formula of chlorine peroxide. 
— What is euchlorine ? — How may iodic acid be made ? — Describe the 
preparation of potassium iodate? 



ACETIC ACID AND OTHER ACETATES. 

Formula of Acetic Acid, HC 2 H 3 2 . Molecular weight, 60. 

Source. — Acetic Acid, the Hydrogen Acetate or Acetate of Hydro- 
gen, is said to occur naturally in certain plant-juices and animal 
fluids in minute proportions, but otherwise is an artificial product. 
Much is furnished by the destructive distillation of wood. When 
first discovered this was regarded as a new acid, and was named 
pyroligneous acid, a hybrid word from irvp, pur, fire, and lignum, 
wood, a term still retained for the crude acid. The latter, neutral- 
ized by calcium carbonate, the whole evaporated, and the residue 
gently heated to drive off volatile tarry matters, gives calcium ace- 
tate, which, after conversion into sodium acetate aud recrystalliz- 
ation, furnishes by distillation with sulphuric acid and water acetic 
acid in a state of purity. Diluted acetic acid is white vinegar, one 
of the now many varieties of vinegar. It has been known as wood 
vinegar for the past sixty years. It is generally colored brown with 
caramel to meet the taste of the public. In Germany and France 
large quantities of acetic acid are made by the spontaneous oxida- 
tion of the alcohol in inferior wines in the presence, according to 
Pasteur, of a plant-ferment termed Mycoderma Aceti (the Bacterium 
Mycodermi of Cohn) ; hence the white- and red-wine vinegar {vinegar, 
from the French vin, wine, and aigre, sour). Indeed, this bacterium 
may be propagated, and the artificial manufacture of vinegar from 
alcohol and water be carried out, by its aid, on a larger scale. In 
England also the domestic form of acetic acid (brown vinegar) com- 
monly has an alcoholic origin : infusion of malt and unmalted grain, 
or sometimes the latter alone after treatment with sulphuric acid, is 
fermented ; and the resulting alteration of its sugar, instead of 
being arrested when the product is an alcoholic liquid, a sort of 
beer, is allowed to go on to the next stage, acetic acid ; it usually 



298 THE ACIDULOUS RADICALS. 

contains from 3 to 6 per cent, of real acetic acid (HC 2 H 3 2 ). Different 
strengths of vinegar are sold under the numbers 16, 18, 20, 22, and 
24, corresponding to the number of grains of anhydrous sodium 
carbonate neutralized by 1 Imperial fluidounce of the vinegar. All 
of these "brewed vinegars" are further colored with caramel to 
suit the popular taste. Vinegar is a generic term applicable to any 
one or to all varieties. Its essential component is acetic acid. 

Official Vinegars. — The British official " vinegar " (Acetum, B. P.) 
contains 5J (5.41) per cent, of acid. The so-called vinegar of can- 
tharides {Acetum Cantharidis, B. P.) is a solution of the active 
principle of cantharides in very strong acetic acid, not in official 
vinegar. The vinegars of squill {Acetum Scillce, U. S. P.) and of 
ipecacuanha (Acetum Ipecacuanha?, B. P.) contain diluted acetic acid ; 
that is, wood vinegar, not the official il vinegar," which is that made 
from malted and unmalted grain, commonly 1 part of the former to 
3 of the latter. In the British Pharmacopoeia " vinegar," except 
rare occasional use for its own sake, is only employed in the prepa- 
ration of Emplastrum Saponis Fuscum. 

The Acetum Opii, U. S. P., or Black Drop of America, is made 
from nutmeg, saffron, and sugar, as well as opium and diluted acetic 
acid. 

The Acetic Radical. — The group C 2 H 3 2 is that characteristic of 
acetic acid and other acetates. It is univalent. 

Acetyl. — The characteristic group in acetates (C 2 H 3 2 ) is consid- 
ered to contain, rather than to be, a radical — the radical C 2 H 3 0, 
termed acetyl. Acetates yield a body having the composition 
C 2 H 3 0C1, which is regarded as acetyl chloride ; from this may be 
obtained acetic anhydride (C 4 H 6 3 ), which, by absorbing water, 
becomes acetic acid. 



C 2 H 3 01 
01 J 


C 2 H 3 } U 


CA0J 


C 2 H 3 0i 


Acetyl 


Acetic 


Acetic acid. 


Metallic 


chloride. 


anhydride. 




acetates. 



The quantitative relation of acetic acid to alcohol will be evident 
from the following equation, representing, empirically, the formation 
of the acid : 

C 2 H 6 + 2 = 2 H 4 2 + H 2 

Alcohol. Acetic acid. 

Acetates in aqueous solution are liable to decomposition. In solu- 
tion of acetate of morphine a myceloid growth occasionally forms, 
acetic acid disappears, and morphine is deposited. Solution of am- 
monium acetate is liable to a similar change, gradually becoming 
alkaline. 

Synthetical Reaction. 

Acetic Acid. 

To a few grains of sodium acetate in a test-tube add a little 
water and some sulphuric acid, and heat the mixture ; acetic 
acid is evolved, and may be condensed by a bent tube adapted 
to the test-tube by a cork in the usual way. 



ACETATES. 299 

Acetic Acid, or Hydrogen Acetate, or Acetate of Hydrogen. — This 
is the process by which sodium or calcium acetate (the neutralized 
products of the distillation of wood) is made to yield acetic acid on 
the large scale. As with nitric and hydrochloric acids, the loose 
term "acetic acid" is that usually applied to aqueous solutions of 
acetic acid. The Acidum Aceticum, U. S. P., contains 36 per cent, of 
real acid — that is, of HC 2 H 3 2 ; for it contains only 30.6 per cent, of 
acetic anhydride (C 4 H 6 3 ), still occasionally though somewhat ob- 
scurely termed anhydrous acetic acid. Its specific gravity is 1.048. 
Acidum Aceticum, Dilutum, U. S. P., contains 6 per cent, of HC 2 H 3 2 . 
Sp. gr. 1.0083. Glacial acetic acid (HC 2 H 3 2 ) contains no water. 
It solidifies to a crystalline mass at and below 15° C. (59° F.), hence 
the appellation glacial (from glacies, ice). Sp. gr. from 1.056 to 
1.058. Good commercial glacial acetic acid {Acidum Aceticum 
Glaciate, U. S. P.) does not contain more than 1 per cent, of water. 
Although water is lighter than this acetic acid, yet addition of water 
at first renders the acid heavier; evidently, therefore, condensation, 
or contraction in bulk, occurs on mixing the liquids : after 10 per 
cent, has been added the addition of more water produces the usual 
effect of dilution of a heavy liquid by a lighter — namely, reduction 
of relative weight. This matter will be better understood after the 
subject of specific gravity has been studied. Glacial acetic acid 
mixes readily with most oils. 

The following equation shows the reaction : 

NaC 2 H 3 2 + H 2 S0 4 = HC 2 H 3 2 -f NaHS0 4 ; 

Sodium Sulphuric Acetic acid. Acid sodium 

acetate. acid. sulphate. 

or, assuming the existence of acetyl (C 2 H 3 0) in acetic acid (united 
with hydroxyl HO), and the radical sulphury 1 (S0 2 ) in sulphuric 
acid (united with 2HO), 

Na} U + H 2 / U 2 - H| U + HNaj U2 ' 

or, on the assumption that salts contain the oxide of a basylous 
radical united with the anhydride of an acid (the old view under 
which such names as acetate of soda were formed), 

Na 2 0,C 4 H 6 3 -f 2H 2 0,S0 3 = Na 2 0,H 2 0,2S0 3 + H 2 0,C 4 H 6 3 . 

Note on the Constitution of Salts. 

Which of these three equations — or, more broadly, which of the 
three views of the constitution of salts illustrated by the equations — 
is correct is questionable. Whether it is C 2 H 3 2 ,C 2 H 3 or C 4 H 6 3 
which migrates from one acetic compound to another, whether it is 
S0 4 , S0 2 , or S0 3 which migrates from one sulphuric compound to 
another, and so on with other acidulous groupings, cannot at present 
be determined. There are some objections to each view, and pos- 
sibly neither is right. Either the given radicals cannot be isolated, 
or application of the forces of heat, light, and electricity do not 
confirm views arrived at by the results of operations with the chem- 
ical force ; or a salt comes to be regarded as having so large a number 



300 THE ACIDULOUS RADICALS. 

of constituent parts that the view breaks down from the sheer in- 
ability of students, at all events at the present stage of study, to 
grasp the complicated analogies involved. Yet for the purposes of 
description, study, and conversation some system must be adopted. 
Let the first, then, be taken for the present, over-reliance on it being 
checked by the use of general instead of special names for the hypo- 
thetical radicals, and other systems be employed in other cases. 
(See also p. 286.) 

Analytical Reactions (Tests). 

First Analytical Reaction. — To an acetate add sulphuric acid 
and heat the mixture ; a characteristic odor (acetic acid) is 
evolved. 

Note 1. — Iodine, sulphurous acid, and other substances of powerful 
odor mask that of acetic acid ; they must be removed, therefore, 
usually by precipitation or oxidation, before applying this test. 

Note 2. — It will be noticed that this reaction is identical with the 
previous one ; it has synthetical or analytical interest according to 
the object and method of its performance. 

Second Analytical Reaction. — Repeat the above reaction, a 
few drops of spirit of wine being first added to the acetate ; 
acetic ether (ethyl acetate, C 2 H 5 C2H 3 2 ), also of characteristic 
odor, is evolved. The basylous radical ethyl (C 2 H 5 ) will be 
referred to subsequently. 

Third Analytical Reaction.- — Heat a fragment of a dry ace- 
tate in a test-tube, and again notice the odor of the gaseous 
products of the decomposition ; among them is acetone 
(C 3 H 6 0), the smell of which is characteristic. Carbonate of 
the metal remains in the test-tube. 

Fourth Analytical Reaction. — To a solution of an acetate, 
made neutral by the addition of acid or alkali as the case may 
be, add a few drops of neutral solution of ferric chloride ; a 
deep-red liquid results, owing to the formation of ferric acetate 
(Fe 2 6C 2 H 3 2 ). Boil ; a red precipitate (iron oxyacetate) oc- 
curs, leaving the liquid colorless. 

Analytical Note. — It will be noticed that the formation of charac- 
teristic precipitates, the usual method of removing radicals from 
solution for recognition, is not carried out in the qualitative analy- 
sis of acetates. This is because all acetates are soluble. Silver 
acetate (AgC 2 H 3 2 ) and mercurous acetate (HgC 2 H 3 2 ) are only 
sparingly soluble in cold water, but the fact can seldom be utilized 
in analysis. Hence peculiarities of color and odor, the next best 
characters on which to rely, are adopted as means by which acetates 
may be detected. Acetates, like other organic compounds, char 
when heated to a high temperature. 

Note on Anhydrides. — Up to this point the student has regarded 
an anhydride as a body derived from an acid by removal of the 



SULPHIDES. 301 

whole of the hydrogen of the acid, together with as much of its 
oxygen as with the hydrogen forms water. This definition will 
scarcely apply to acetic anhydride, and must therefore be somewhat 
qualified. An anhydride is derived from an acid, the acid having 
lost the whole of its basylous hydrogen and so much oxygen as is 
necessary to form water with that hydrogen. Anhydrides are 
obtained by heating acids and by other methods. 



QUESTIONS AND EXEECISES. 

What is the formula of acetic acid? — State the relation of acetic acid 
to other acetates. — What is the molecular weight of acetic acid? — Name 
the sources of acetic acid. — What is pyroligneous acid ? — From what com- 
pound is the acetic acid of most foreign and English varieties of vinegar 
derived? — How much real acid is contained in official vinegar? — What 
is the nature of the " vinegars" of pharmacy? — How may acetic acid be 
obtained from sodium acetate? — How much real acid is contained in the 
official acetic acid ? — Mention the strength of commercial glacial acetic 
acid. — Give three or more views of the constitution of acetates, illus- 
trating each by formulae. — Enumerate the tests for acetates. 



HYDROSULPHURIC ACID AND OTHER SULPHIDES. 

Formula of Hydrosulphuric Acid, H 2 S. Molecular weight, 34. 

Source and Varieties of Sulphur. — The acidulous radical of hydro- 
sulphuric acid, sulphydric acid, hydrogen sulphide, or sulphuretted 
hydrogen and other sulphides is the element sulphur (S). It occurs 
in nature in the free condition, also in combination with metals, as 
already stated in describing the ores of some of the metals. The 
coal-gas industry furnishes much sulphur as a by-product, it occur- 
ring in coal, chiefly as iron pyrites. Most of the sulphur used in 
medicine is imported from Sicily, where it occurs chiefly associated 
with blue clay. It is purified by fusion, sublimation, or distillation. 
Melted and poured into moulds, it constitutes a crystalline mass 
termed roll sulphur. If distilled and the vapor carried into large 
chambers, so that it may be rapidly condensed, the crystals are so 
minute as to give the sulphur a pulverulent character ; this is sub- 
limed sulphur (Sulphur Sublimatum, U. S. P.) or flowers of sulphur : 
the same washed with dilute ammonia, to remove the traces of sul- 
phuric acid (often 0.1 per cent., resulting from very slow oxidation 
of sulphur in ordinary moist air) or, possibly, arsenous sulphide, 
constitutes Sulphur Lotum, U. S. P. The third common form, milk 
of sulphur, will be noticed subsequently. Sulphur also occurs in 
nature in combination as a constituent of animal and vegetable tis- 
sues, as sulphurous acid gas (S0 2 ) in volcanic vapors, and as sul- 
phuretted hydrogen in some mineral waters. Plastic sulphur is 
one of the allotropic varieties of the element, obtained on heating 
sulphur considerably beyond its melting-point and pouring into cold 
water. 

Quantivalence. — Sulphur would seem to be sexivalent in sulphuric 
anhydride (S0 3 ), a substance which will be noticed under Sulphuric 
14 



302 THE ACIDULOUS RADICALS. 

Acid, and quadrivalent in sulphurous anhydride (S0 2 ), while it still 
oftener exhibits bivalent affinities (II 2 S). 

Molecular Weight. — At very high temperatures sulphur follows 
the rule that, under similar conditions of heat and pressure, molecu- 
lar weights (in grammes, grains, etc.) of volatile elements occupy 
equal volumes of vapor ; its formula therefore is S 2 , and molecular 
weight 64. At lower temperatures the volume weighs three times 
as much as it should do if following usual laws, and then the 
molecule would appear to contain six atoms (S 6 ). 

Acid Salts. — Sulphur (S /7 ) being the first acidulous radical of 
bivalent activity met with in these sections on acids, it is desirable 
here to draw attention to a new class of salts to which such a radical 
will give rise. These are acid salts (as KHS0 4 ), which are inter- 
mediate between neutral salts (as K 2 S0 4 ) and acids (as H 2 S0 4 ). 
Univalent acidulous radicals, with an atom of hydrogen, give an 
acid, and with an atom of other basylous radicals an ordinary or 
neutral salt. But bivalent acidulous radicals, inasmuch as they 
give with two atoms of hydrogen an acid, and with two atoms of 
univalent metals a neutral salt, may obviously give intermediate 
bodies containing one atom of hydrogen and one atom of metal •, 
these are appropriately termed acid salts : they are neither normal 
acids nor neutral salts, but acid salts. (Examples : KHC0 3 , 
NaHS0 4 , KIIC 4 1I 4 6 , Na 2 IIP0 4 , CuHAs0 3 , CaII 4 2P0 4 .) Whether 
or not these and other salts give an acid reaction with blue litmus- 
paper depends on the strength of the respective radicals. Usually 
they do redden the test-paper, but sometimes not ; thus potassium, 
sodium, or ammonium acid sulphides or sulphydrates (KITS, NallS, 
NIIJFIS) have alkaline properties.* 

The chemical analogy between sulphur and oxgen, already once 
alluded to (p. 177), is further illustrated by the compounds just 
mentioned. Thiacetic acid (CH 3 .CO.SII) exists, and other thio 
(detov, theion, sulphur) acids. Sulphur is also closely related to the 
rarer element selenium. Thus we have Se0 2 (selenious anhydride) 
as well as S0 2 (sulphurous anhydride), II 2 Se0 3 (selenious acid) as 
well as H 2 S0 3 (sulphurous acid), II 2 Se0 4 (selenic acid) as well as 
II 2 S0 4 (sulphuric acid). The rare element tellurium also seems to 
have similar analogies. The four hydrogen compounds of the group 
have the formulae H 2 0, II 2 S, H 2 Se, ELTe. (Vide Index, "Periodic 
Law/') 

Synthetical Reactions. 

Hydrogen Sulphide, or Sulphuretted Hydrogen. 

Synonyms. — Ilydrosulphuric Acid ; Sulphydric Acid. 

First Synthetical Reaction. The preparation of sulphuretted 



* Chemists regard these sulphydrates as compounds of basylous radi- 
cals with HS, a univalent grouping termed hydrosulphyl (hydrogen 
persulphide, H2S2), just as hydrates are similarly viewed as compounds 
of the univalent radical hydroxy] (HO) (hydrogen peroxide, H2O2), H2S 
becoming HHS (hydrogen hydrosulphylide), and H2O becoming HHO 
(hydrogen hydroxy lide). 



SULPHIDES. 303 

hydrogen. — This operation was described on p. 97, and prob- 
ably has already been studied by the reader. 

Precipitated Sulphur. 

Second Synthetical Reaction. — Prepare the variety of the 
radical of sulphides known as Precipitated Sulphur {Sulphur 
Prsecipitatum, U. S. P.) or Milk of Sulphur, by boiling a few 
grains of flowers of sulphur (100 parts) with slaked lime (50 
parts) and some water (500 parts) in a test-tube (larger quan- 
tities in an evaporating-basin), filtering, and (reserving a small 
portion of the filtrate) adding diluted hydrochloric acid until 
the well-stirred milk-like liquid still has a faint alkaline or 
scarcely acid reaction on test-paper ; sulphur is precipitated, 
and may be collected on a filter, washed, and dried (at about 
130° F.). Excess of acid must be avoided, or some hydrosul- 
phyl, the liquid hydrogen persulphide (H 2 S 2 ), will be formed, 
probably causing the particles of sulphur to aggregate to a 
gummy mass. 

This is the process of the "pharmacopoeias. Calcium polysul- 
phide and calcium hyposulphite are formed : 

3CaH 2 2 + 6S 2 = 2CaS 5 + CaS 2 3 + 3H 2 

Calcium Sulphur. Calcium Calcium Water, 

hydrate. polysulphide. hyposulphite. 

On adding the acid both salts are decomposed and, after an 
intermediate reaction, sulphur separates : 
2CaS 5 + CaS 2 3 + 6HC1 = 3CaCl 2 + 3H 2 + 6S 2 

Calcium Calcium Hydrochloric Calcium Water. Sulphur, 

polysulphide. hyposulphite. acid. chloride. 

The calcium polysulphide yields sulphuretted hydrogen and milk- 
white sulphur on the addition of acid. The calcium hyposulphite 
then yields sulphurous acid gas as well as yellowish sulphur. The 
gases react, and give sulphur and water, very little sulphuretted 
hydrogen escaping: this is the intermediate reaction just alluded to. 
A little pentathionic acid (see Index) is also said to be formed. 
4H 2 S + 2S0 2 = 3S 2 + 4H 2 0. 

Sulphur Lozenges (Trochisci Sulphuris, B. P.) contain, each, 5 
grains of precipitated sulphur, 8 grains of sugar, 1 grain of gum 
and of crear 
orange-peel. 

Calcareous Precipitated Sidphur, the old " Milk of Sul- 
phur." — To a sulphur solution prepared as before (or to the 
reserved portion) add a little diluted sulphuric acid ; the pre- 
cipitate is in this case largely mixed with calcium sulphate : 

2CaS 5 + CaS 2 3 + 3H 2 S0 4 + 3H 2 = 3(CaS0 4 ,2H 2 0) + 6S 2 

Calcium Calcium Sulphuric Water. Calcium sulphate. Sulphur, 

polysulphide. hyposulphite, acid. 



304 THE ACIDULOUS RADICALS. 

Place a little of each of these specimens of " precipitated 
sulphur," with a drop of the supernatant liquid, on a strip of 
glass, cover each spot with a piece of thin glass, and examine 
the precipitates under a microscope ; the pure sulphur will be 
found to consist of minute grains or globules, the calcareous 
to contain comparatively large crystals (hydrous calcium sul- 
phate). 

Note. — Some of the precipitated sulphur met with in trade is, in 
England, still thus mixed with calcium sulphate, most of such speci- 
mens containing two-thirds of their weight of that substance. 
Formerly, purchasers were so accustomed to the satiny appearance 
of the mixed article as to regard real sulphur with suspicion, some- 
times refusing to purchase it. The mixed article is certainly some- 
what more easily miscible with aqueous liquids. 

Calcareous precipitated sulphur yields a white ash (anhydrous 
calcium sulphate) when a little is burnt off on the end of a table- 
knife or spatula or in a crucible. (No more damage is done to the 
steel than a rub on a knife-board will remove.) To ascertain exactly 
the amount of the sulphate, place a weighed quantity in a tared 
crucible and heat till no more vapors are evolved. The weight of 
the residual anhydrous calcium sulphate (CaS0 4 = 136), with one- 
fourth thereof added, is the amount of crystalline calcium sulphate 
(CaS0 4 ,2H 2 = 172) present in the original quantity of calcareous 
sulphur. 

Analytical Keactions (Tests). 

To a sulphide add a few drops of hydrochloric acid ; sul- 
phuretted hydrogen will probably be evolved, well known by 
its smell. If the sulphide is not acted upon by the acid or if 
free sulphur be under examination, mix a minute portion with 
a fragment of solid caustic potash or soda and fuse on a silver 
coin or old spoon. When cold, place a drop of dilute hydro- 
chloric acid on the spot; sulphuretted hydrogen is evolved, 
and a black stain, due to silver sulphate (Ag 2 S), is left on the 
coin. 

Other sulphur reactions may be adapted as tests, but the above 
are sufficient for all ordinary purposes. The most convenient reagent 
for detecting a sulphide in solution of ammonia is copper ammonio- 
sulphate, which gives a black precipitate (copper sulphide) if a sul- 
phide be present. 

The Sulphur Iodide (S 2 I 2 ) has been mentioned under " Iodine." 
A chloride "(S 2 C1 2 ) and bromide (S 2 Br 2 ) may also be formed from 
their elements. A mixture of sulphur and sulphur chloride is 
sometimes met with under the name of sulphur hypochloride. 



QUESTIONS AND EXERCISES. 
In what forms does sulphur occur in nature ? — State the modes of prep- 
aration of the three chief commerical varieties of sulphur. — To what 



SULPHITES. 305 

extent does the atom of sulphur vary in quantivalence? — State the rela- 
tions of acid salts to acids and to normal salts. — Define sulphides and 
sulphydrates. — Describe the preparation of sulphuretted hydrogen. — 
What are the characters of pure precipitated sulphur ? — Give equations 
explanatory of the reactions which occur in precipitating sulphur accord- 
ing to the official process. — Describe the microscopic test for calcareous 
precipitated sulphur. — Mention a ready physical method of detecting 
calcium sulphate in precipitated sulphur. — Mention the tests for sul- 
phides and the character by which sulphuretted hydrogen is distin- 
guished from other sulphides. — How are sulphides insoluble in acids 
tested for sulphur ? — How would you detect a trace of sulphur in ammo- 
nia solutions? 



SULPHUROUS ACID AND OTHER SULPHITES. 

Formula of Sulphurous Acid, H 2 S0 3 . Formula of Sulphurous Acid 
Gas or Sulphurous Anhydride, sometimes termed Sulphurous 
Acid, S0 2 . Molecular weight of Sulphurous Acid, 82 ; of the 
Anhydride, 64. 

When sulphur is burnt in the air it combines with oxygen and 
forms sulphurous acid gas (S0 2 ), more correctly termed sulphurous 
anhydride, or occasionally, but erroneously, sulphurous acid. It is 
a pungent, colorless gas, readily liquefied on being passed through 
a tube externally cooled by a freezing-mixture composed of 2 parts 
of well-powdered ice (or, better, snow) with 1 part of common salt. 
If sulphurous acid gas becomes moist or is passed into water, heat 
is evolved and true sulphurous acid (H 2 S0 3 ) is formed. The latter 
body may be obtained in crystals by freezing a strong aqueous solu- 
tion •, but it is very unstable, and hence the properties of the sul- 
phurous radical must be studied under the form of some other sul- 
phite ; calcium sulphite (CaS0 3 ) or sodium sulphite (Na 2 S0 3 ) may 
be used for the purpose. 

Quantivalence. — The radical of the sulphites is bivalent (SO/ 7 ), 
and hence forms acid sulphides, such as acid potassium sulphite 
(KHS0 3 ), and neutral sulphides, such as sodium sulphite (Na 2 S0 3 ). 

Note on Nomenclature. — The sulphites are so named from the 
usual rule, that salts corresponding with acids whose names end in 
ous have a name ending in ite. They are generally made by pass- 
ing sulphurous acid gas over moist oxides or carbonates ; in the 
latter case carbonic acid gas escapes. 

Synthetical Reaction. — To a few drops of sulphuric acid in 
a test-tube add a piece of charcoal and apply heat ; sulphurous 
acid gas is evolved, and may be conveyed by a bent tube into 
a small quantity of cold water in another test-tube. Larger 
quantities of the gas may be made in a Florence flask. The 
fluid product is the Acidum Sulphurosum, U. S. P. It should 
contain not less than 6.4 of the gas (S0 2 ), and have a sp. gr. 
of not less than 1.035. The process is also that described in 
the Pharmacopoeia, except that the gas is purified by passing 
through a small wash-bottle before the final collection. 



306 THE ACIDULOUS RADICALS. 



4H 2 S0 4 


+ c 2 = 


2C0 2 


+ 


4H 2 


+. 4S0 2 


Sulphuric 


Carbon 


Carbonic 




Water. 


Sulphurous 


acid. 


(charcoal). 


acid gas. 






acid gas. 



Sulphurous acid gas may also be made by boiling copper, 
mercury, or iron with sulphuric acid, sulphate of the metal 
being formed ; also by boiling sulphur with sulphuric acid. 
The gas passed into water forms sulphurous acid. 

SO, + H 2 == H 2 S0 3 

Sulphurous acid gas. Water. Sulphurous acid. 

If in this process the water were replaced by solutions of, or solid, 
metallic oxides or carbonates, sulphites of the various metals would 
be formed. The formula of sodium sulphite (Sodii Sulphis, U. S. 
P., the old sulphite of soda) is Na 2 S0 3 ,7H 2 ; it occurs in colorless 
efflorescent prisms, soluble in water or spirit : under the name of 
antichlor it is used for removing traces of chlorine from paper pulp. 
The formula of sodium bisulphite (Sodii Bisulphis, U. S. P.) is 
NaHS0 3 . The so-called Bisulphite of Lime, used by brewers for 
retarding or arresting fermentation and oxidation, and employed 
for various antiseptic purposes, is a solution of calcium sulphite 
(CaS0 3 ) in free sulphurous acid (H 2 S0 3 ), and is made by passing 
sulphurous acid gas (S0 2 ) into thin milk of lime. Its specific 
gravity varies from 1.050 to 1.070, and its potential strength of 
anhydride (S0 2 ) from 4 to 6 per cent. Sulphurous acid is very sol- 
uble in alcohol. 

Analytical Ke actions (Tests). 

First Analytical Reaction. — To a sulphite (sodium sulphite, 
for instance, made by passing sulphurous acid gas into solution 
of sodium carbonate) add a drop or two of diluted hydro- 
chloric acid ; a well-known peculiarly pungent smell results 
(sulphurous acid). 

This smell is the same as that evolved on burning lucifer-matches 
that have been tipped with sulphur. It is due probably not to the 
gas (S0 2 ), but to the sulphurous acid (H 2 S0 3 ) formed by the union 
of sulphurous acid gas with either the moisture of the air or that 
on the surface of the mucous membrane of the nose. The gas is 
highly suffocating. 

Second Analytical Reaction. — To a sulphite add a little water, 
a fragment or two of zinc, and then hydrochloric acid ; sul- 
phuretted hydrogen will be evolved, known by its odor and by 
its action on a piece of paper placed like a cap on the mouth 
of the test-tube and moistened with a drop of solution of lead 
acetate, black lead sulphide being formed. Sulphurous acid 
may be detected in acetic acid or in hydrochloric acid by this 
test : H 2 S0 3 + 6H = H 2 S + 3H 2 0. 



SULPHATES. 307 

Other Analytical Reactions. 

To solutions of neutral sulphites add barium nitrate or chlo- 
ride, calcium chloride, or silver nitrate ; in each case white pre- 
cipitates result (sulphites of the various metals). The barium 
sulphite is soluble in weak hydrochloric acid ; but if a drop or 
two of chlorine-water is first added, barium sulphate is formed, 
which is insoluble in acids. The other precipitates are also 
soluble in acids. The silver sulphite is decomposed on boiling, 
sulphuric acid being formed and metallic silver set free, the 
mixture darkening in color. 

To recognize the three radicals in an aqueous solution of sul- 
phides, sulphites, and sulphates add barium chloride, filter, and 
wash the precipitate. In the filtrate sulphide are detected by the 
sulphuretted hydrogen evolved on adding an acid. In the precip- 
itate sulphites are detected by the odor of sulphurous acid, produced 
on adding hydrochloric acid, and sulphates by their insolubility in 
the acid. 



QUESTIONS AND EXERCISES. 

What are the differences between sulphurous acid and sulphurous acid 
gas, sulphites and acid sulphites ?— State the characters of sulphurous 
acid gas. — How is the official sulphurous acid prepared ? — By what tests 
may sulphurous acid be recognized in acetic acid ? — Give a method by 
which sulphites may be detected in presence of sulphides and sulphates. 



SULPHURIC ACID AND OTHER SULPHATES. 

Formula of the acid, H 2 S0 4 or S0 2 (OH) 2 . Molecular weight, 98. 

Many sulphates occur in nature, but the common and highly im- 
portant hydrogen sulphate, sulphuric acid, is made artificially. 

Preparation of the Acid. — General Nature of the Process. — Sul- 
phur itself, or generally the sulphur in iron pyrites, is first con- 
verted into sulphurous acid gas by burning in air, and this gas, by 
moisture and oxygen, into sulphuric acid (S0 2 + H 2 + = H 2 S0 4 ). 

Details of the Process. — The oxygen necessary to oxidize the sul- 
phurous acid gas cannot directly be obtained from air, but indirectly, 
the agency of nitric oxide (NO) and nitrous anhydride (N 2 3 ) being 
employed, these gases becoming nitric peroxide (N0 2 ) by action of 
the air, and the nitric peroxide again becoming .reduced by the 
action of the sulphurous acid gas, and so on. A comparatively 
small quantity of nitric gases will thus act as carrier of oxygen 
from the air to very large quantities of sulphurous acid. 

The nitric oxide and nitrous anhydride are, in the first instance, 
obtained from nitric acid, and this from sodium nitrate, by the 
action of a small quantity of the sulphuric acid of a previous 
operation. 



308 



THE ACIDULOUS RADICALS. 



The following equations represent the chief successive steps : 

2NaN0 3 + H 2 S0 4 = Na 2 S0 4 + 2HN0 3 

2H 2 + 3S0 2 + 2HN0 3 = 3H 2 S0 4 + 2NO 

2SO, + H 2 + 2HN0 3 = 2H 2 S0 4 -f N 2 3 



2NO -f 2 = 2N0 2 



+ = 2N0 2 



2S0 2 + 2N0 2 + 2H 2 = 2H 2 S0 4 + 2NO 

Possibly the nitrous anhydride may, instead of absorbing oxygen, 
yield oxygen and become reduced to nitric oxide, or may act in both 

OH 



ways. Probably also nitrosulphonic acid S0 2 <[™-q is formed both 

from nitrous anhydride and nitric peroxide, and is then resolved by 
the steam into sulphuric acid and the lower oxides. And so on, 
over and over again. 

2S0 2 + 3N 2 3 + H 2 = 2S0 2 (OH)(N0 2 ) 4- 4NO 
4S0 2 + 6N0 2 + 2H 2 = 4S0 2 (OH)(N0 2 ) 4- 2NO 
2SO a (OH)(NO) 2 + H 2 = 2H 2 S0 4 + N 2 3 
4S0 2 (OH)(N0 2 ) 4- 2H 2 = 4H 2 S0 4 + 2N0 2 4- 2NO 

On the large scale the sulphurous acid gas is carried, together 
with the nitric vapors, by flues into leaden chambers, where jets of 
steam supply the necessary moisture. The resulting dilute sul- 

Fig. 38. 




Experimental Manufacture of Sulphuric Acid. 

phuric acid is concentrated by evaporation in leaden, and finally in 
glass or platinum, vessels. 






SULPHATES. 309 

Other Processes. — Sulphuric acid may be obtained by other pro- 
cesses, as by distilling ferrous sulphate resulting from the natural 
oxidation of iron pyrites by air ; but it is not so made at the present 
day. The ferrous sulphate was formerly called green vitriol (p. 144), 
and the distilled product oil of vitriol, the latter in allusion to its 
consistence and origin. 

Experiment. — For purposes of practical study a small quantity 
may be made, as shown in Fig. 39, by passing (a) sulphurous acid 
gas (p. 305), (b) nitric oxide in small quantity (p. 289), (c) air (forced 
through by aid of bellows or a gas-holder, or drawn through a 
water-aspirator, e), and occasionally (d) steam (generated in a Flor- 
ence flask), through glass tubes nearly to the bottom of a two- or 
three-quart flask. 

A slow current of sulphurous acid gas, air, and steam and a 
small quantity of nitric oxide will furnish, in the course of a few 
minutes, enough sulphuric acid for recognition by the first of the 
following analytical reactions. The manufacturing process may be 
more exactly imitated by burning sulphur in a tube placed where 
the flask a is represented in the foregoing figure, or by burning it 
under a funnel there attached ; but in either case strong aspiration 
must be maintained. An instructive result also will follow the 
cessation of the steam-current for a short time — namely, the growth 
on the inner surface of the large flask of" chamber crystals," which 
are either nitro-sulphonic acid or nitrosyl-sulphuric acid : 

s ° 2 < N o 2 S0 2<NO - 0. 

Nitro-sulphonic acid. Nitrosyl-sulphuric acid. 

Purification. — Sulphuric acid may contain arsenic, nitrous com- 
pounds, and salts (lead sulphate, etc.). Arsenic may be detected by 
the hydrogen test (p. 173) or the stannous-chloride test (p. 175), 
nitrous compounds by powdered ferrous sulphate (which acquires a 
violet tint if they are present), and salts by the residue left on boil- 
ing a little to dryness in a crucible in a fume-chamber. If only 
nitrous compounds are present, the acid may be purified by heat- 
ing with about \ per cent, of ammonium sulphate, water and nitro- 
gen being produced (Pelouze). If arsenic occurs, heat with a little 
nitric acid (or sodium nitrate), which converts arsenous anhydride 
(As 2 3 ) into arsenic anhydride (As 2 5 ), then add ammonium sul- 
phate, and distil in a retort containing pieces of quartz and heated 
by an annular-shaped burner (to prevent "bumping" — see p. 282). 
This is the usual process of purification. The arsenic anhydride 
remains in the retort. (Arsenous anhydride would be carried over 
with the sulphuric acid vapors.) The distillation frees the acid 
from other salts (such as NaHS0 4 ) which are not volatile. 

Quantivalence. — The sulphuric radical being bivalent (SO/ 7 ), 
acid as well as neutral sulphates may exist. Acid potassium sul- 
phate (KHS0 4 ) is an illustration of the former, sodium sulphate 
(Na 2 S0 4 ) of the latter -, double sulphates may also occur, such as 
potassium and magnesium sulphate (K 2 S0 4 ,MgS0 4 ,6H 2 0). Sul- 
phates generally contain water of crystallization. 
14* 



310 THE ACIDULOUS RADICALS. 

Pure sulphuric acid (H 2 S0 4 ) is of specific gravity 1.848. The 
best "oil of vitriol" of commerce, a colorless liquid of oily consist- 
ence, is of specific gravity 1.843, and contains about 98 per cent, of 
real acid (H 2 S0 4 ). This is the Acidum Sulphuricum, B. P. A 
variety less pure than this "white " acid is known as " brown acid." 
The Acidum Sulphuricum, U. S. P., should not contain less than 
92.5 per cent, of the pure acid (H 2 S0 4 ) and a sp. gr. not below 
1.835. The Acidum Sulphuricum Dilutum, U. S. P., contains 10 per 
cent, of the pure acid and has a sp. gr. of about 1.070, the dilu- 
tion commonly resulting in the separation, as a slight white sediment, 
of lead sulphate usually present in the strong acid. Acidum Sul- 
phuricum Aromaticum, U. S. P., an acid greatly diluted with alcohol, 
in which are dissolved oil of cinnamon and tincture of ginger, con- 
tains about 20 per cent, by weight of official acid ; sp. gr. about 
0.939. It has been stated that in this preparation the acid and 
alcohol form some sulphovinic acid or ethyl-sulphuric acid, but the 
author has been unable to detect the latter. There are some definite 
compounds of sulphuric acid with water ; the first (H 2 S0 4 ,H 2 0) may 
be obtained in crystals. 

Sulphuric anhydride (S0 3 ) occurs in white crystals. It was for- 
merly called anhydrous sulphuric acid, but it has no acid properties. 
It may be made by distilling sulphuric acid with phosphoric anhy- 
dride (H 2 S0 4 + P 2 5 = 2HP0 3 + S0 3 ). On the large scale sulphuric 
acid is dissociated by heat, and the dried sulphurous anhydride and 
oxygen made to recombine. It appears to unite with sulphuric acid 
and some other sulphates to form compounds (B/ 2 S0 4 ,S0 3 ) resem- 
bling in constitution red potassium chromate or pyrochromate. The 
fuming sulphuric acid (H 2 S0 4 ,S0 3 ), sometimes termed pyrosulphuric 
acid (H 2 S 2 7 ), formerly made at Nordhausen in Saxony, seems to 
be such a body. 

Note. — Sulphuric acid is a most valuable compound to all chemists 
and manufacturers of chemical substances. By its agency, direct or 
indirect, many, if not most, chemical transformations are effected. 
To describe all its uses would be to write a work on Chemistry. 

Analytical Reactions (Tests). 

First Analytical Reaction. — To solution of a sulphate add 
solution of a barium salt ; a white precipitate (barium sulphate, 
BaS0 4 ) falls. Add nitric acid and boil the mixture ; the pre- 
cipitate does not dissolve. 

This reaction is as highly characteristic of sulphates as it has 
been stated to be of barium salts. ( Vide p. 104.) The only error 
likely to^ be made in its application is that of overlooking the fact 
that barium nitrate and chloride are less soluble in strong acid than 
in water. On adding the barium salt to the acid liquid, therefore, a 
white precipitate may be obtained, which is simply barium nitrate 
or chloride. The appearance of such a precipitate differs consider- 
ably from that of the barium sulphate ; hence a careful operator 
will not be misled. Should any doubt remain, water should be 



SULPHATES. 311 

added, which will dissolve the nitrate or chloride, but not affect the 
sulphate. 

Second Analytical Reaction. — Mix a fragment of an insol- 
uble sulphate (BaS0 4 , e. g.~) with potassium or sodium car- 
bonate, or, better, with both carbonates, and fuse the mixture 
in a small crucible. Digest the residue, when cold, in water, 
and filter ; the filtrate may be tested for the sulphuric radical. 

This is a convenient method of qualitatively analyzing insoluble 
sulphates, such as those of barium and lead. 

Third Analytical Reaction — Mix a fragment of an insoluble 
sulphate with a little alkaline carbonate on a piece of charcoal, 
taking care that some of the charcoal-dust is included in the 
mixture. Heat the little heap in the blowpipe flame until it 
fuses, and when cold add a drop of acid ; sulphuretted hydro- 
gen is evolved, recognized by its odor. 

This is another process for the recognition of insoluble sulphates. 
Other preparations of sulphur, and sulphur itself, give a similar re- 
sult. It is, therefore, rather a test for sulphur and its compounds 
than sulphates only, but the absence of other salts can be determined 
previously. 

Note. — The presence of the sulphuric radical in a solution having 
been proved by the above reactions, its occurrence as a neutral sul- 
phate of a metal is demonstrated by the neutral or nearly neutral 
deportment of the liquid with test-paper and the detection of the 
metal ; its occurrence as sulphuric acid or an acid sulphate by the 
sourness of the liquid to the taste and the abundant effervescence 
produced on the addition of a carbonate. 

Antidote. — In cases of poisoning by strong sulphuric acid, solution 
of sodium carbonate (common washing soda), magnesia and water, 
etc. may be administered as antidotes. 



QUESTIONS AND EXEECISES. 



State the formula and molecular weight of sulphuric acid. — How is it 
related to other sulphates ? — Write a short article on the manufacture 
of sulphuric acid, giving either diagrams or equations. — How may nitrous 
compounds be detected in and eliminated from sulphuric acid?— State 
the method for detecting arsenic in sulphuric acid, and explain the pro- 
cess by which it may be removed. — Define sulphates, acid sulphates, and 
double sulphates.— What percentage of real acid is contained in oil of 
vitriol? — State the strength of "diluted" and "aromatic" sulphuric 
acid. — By what process is sulphuric anhydride obtained from the ordinary 
sulphuric acid ? — Explain the reactions which occur in testing for sul- 
phates. — Ascertain by calculation the weight of oil of vitriol (of 96.8 per 
cent.) necessary for the production of 1 ton of dry ammonium sulphate. 
Ans. 1718 lbs. — Name the antidotes in cases of poisonjng by strong sul- 
phuric acid. 



312 THE ACIDULOUS RADICALS. 

CARBONIC ACID AND OTHER CARBONATES. 

Formula of the acid, H 2 C0 3 or CO(OH) 2 . Molecular weight, 
62. Formula of Carbonic Acid Gas or Carbonic Anhydride, 
commonly termed Carbonic Acid, C0 2 . Molecular weight, 44. 

Sources. — Carbonates (compounds containing the grouping C0 3 ) 
are very common in nature, the calcium carbonate (CaC0 3 ) being 
widely distributed as chalk, limestone, or marble. The hydrogen 
carbonate, true carbonic acid, is not known, unless, indeed, carbonic 
acid gas assumes that condition on dissolving in water. Such a 
solution (see p. 86) changes the color of blue litmus-paper, and the 
gas does not ; this may be because only the true acid (H 2 C0 3 ) affects 
the litmus, or because the gas (C0 2 ) cannot come into real contact 
with the litmus without a medium. From the commonest natural 
carbonate, calcium carbonate, is derived the carbonic constituent of 
the one most frequently used in medicine and in the arts generally, 
sodium carbonate. 

Sodium Carbonate, the old carbonate of soda, is prepared from the 
chief natural salt, the chloride, by two different processes. The first 
is "the Leblanc process." After the chloride has been converted 
into sulphate (salt cake) by sulphuric acid (or by sulphurous acid, 
air, and steam — Hargreave's modification), 2NaCl -f- H 2 S0 4 = Na 2 S0 4 
4- 2HC1, the sulphate is roasted with limestone and small coal, sodium 
carbonate and calcium sulphide being formed : Na 2 S0 4 + C 2 -j- CaC0 3 
= CaS -\- Na 2 C0 3 + 2C0 2 . The residual mass (black ash) is digested 
in water, in which the sodium carbonate dissolves, the calcium sul- 
phide remaining insoluble. The solution is evaporated to dryness, 
and yields crude sodium carbonate. This is roasted with a small 
quantity of sawdust to convert any caustic soda, resulting from the 
action of the lime on the carbonate, into neutral carbonate. The 
product is soda-ash. Dissolved in water and crystallized, it consti- 
tutes the ordinary " soda " used for washing purposes : recrystallized, 
and sometimes ground, it forms the official sodium carbonate (Sodii 
Carbonas, U. S. P.) (Na 2 CO 3 ,10H 2 O.) The reaction will be more in- 
telligible if regarded as occurring in two stages: 1st, reduction of 
the sodium sulphate to sulphide by the carbon of the coal, Na 2 S0 4 
-J- C 2 = Na 2 S-f-2C0 2 •, 2d, reaction of the sodium sulphide and cal- 
cium carbonate, giving soluble sodium carbonate ; thus, Na 2 S + CaC0 3 
= Na 2 C0 3 + CaS. 

2NaCl + H 2 S0 4 + CaC0 3 + C 2 = Na 2 C0 8 + CaS + 2HC1 -f 2C0 2 

The raw materials. The factory products. 

The sulphur in the residual calcium sulphide may be recovered 
by exposure to the action of the waste carbonic acid gas of lime- 
kilns, calcium carbonate being formed, and the diluting nitrogen 
passing off, more carbonic acid afterward causing sulphuretted 
hydrogen to be set free. The latter is either burnt and converted 
into sulphuric acid, or is caused to react with air on ferric oxide, 
sulphur being set free. 

The other process is " the ammonia process," so called because 
ammonia (NH 3 ) is used over and over again as the chief agent — or 



CARBONATES. 313 

chemical tool, so to say — in the factory. Strong brine from salt- 
beds is saturated first with ammonia gas (from coal which also 
yields gaseous fuel and coke), and then with carbonic acid gas (from 
coke-heated limestone). Sodium bicarbonate falls as a precipitate, 
and is afterward heated to furnish the sodium carbonate, with simul- 
taneous temporary recovery of part of the carbonic acid gas. The 
ammonium chloride concurrently produced is, by the latest improve- 
ments, separated and heated, and its vapors passed over magnesia, 
magnesium chloride and regenerated ammonia gas resulting. Air 
passed over the heated magnesium chloride furnishes chlorine and 
recovered magnesia. The chlorine passed over lime (from the lime- 
stone) furnishes chlorinated lime. The former part of this process 
was discovered by D}^ar and Hemming in 1838, and was applied, 
chiefly by Solvay, from 1861 to 1872; the working out of the chlo- 
rine-recovery by the magnesia method is largely due to Mond. 
The following notes will aid the student : a. Coal yields ammonia 
gas, gaseous fuel, and coke. b. CaC0 3 = CaO + C0 2 . c. 2NaCl + 
2NH 3 + 2C0 2 + 2H 2 = 2NaHC0 3 + 2NH 4 C1. d. 2NaHC0 3 = 
Na 2 C0 3 + H 2 + C0 2 . e. 2NH 4 C1 4- MgO = MgCl 2 + 2NH 3 4- 
H 2 0. /. MgCl 2 + = MgO + Cl 2 . g. Cl 2 + CaO = CaOCl 2 . (If 
the chlorine-recovery is not practised, then 2NH 4 C1 -\- CaO = 
2NH 3 4~ CaCl 2 , the latter being lost.) Rarely is a process carried 
on with such economy of elements as here obtains, while the salt, 
limestone, and fuel occur in England in close contiguity. After 
these raw materials, labor, wear and tear, loss, and capital are all 
paid for, single 1-cwt. casks of powdered bicarbonate (NaHC0 3 ) or 
of granular monohydrous carbonate (Na 2 C0 3 ,H 2 0) can be supplied 
in Great Britain at one penny per pound. 

2NaCl + CaC0 3 -f- = Na 2 C0 3 + CaOCl 2 

The raw materials. The factory products. 

Carbonic Acid Gas (C0 2 ), termed also Carbon Dioxide and Car- 
bonic Anhydride, is a product of the combustion of all carbonaceous 
matters. It is constantly exhaled by animals and inhaled by plants, 
its intermediate storehouse being the atmosphere, throughout which 
it is equally distributed by diffusion {vide p. 24) to the extent of 
about 4 parts in 10,000. A larger proportion than that just men- 
tioned gives to confined air depressing effects, 4 or 5 per cent, ren- 
dering the atmosphere poisonous when taken into the blood from 
the lungs. Carbonic acid, however, may be taken into the stomach 
with beneficial sedative effects ; hence, probably, much of the value 
of such effervescing liquids as soda-water, lemonade, and solutions 
of the various granulated preparations and effervescing powders. 
The gas liquefies on being compressed, and the liquid solidifies on 
being cooled. The weights of equal bulks of the gas, of air, and 
of hydrogen are as 22, 14.44, and 1. At common temperatures it 
dissolves in about its own volume of water, both being under the 
same pressure, the water retaining gas strongly if all air has been 
expelled. 

Sulphocarbonates resemble carbonates in constitution, but contain 
sulphur in place of oxygen. 



314 THE ACIDULOUS RADICALS. 

Sulphocarbonic Anhydride, CS 2 , commonly termed Carbon Bisul- 
phide or Bisulphide (Carbonei Disulphidum, U. S. P.), is a highly- 
volatile and inflammable liquid, easily made from its elements. Sp. 
gr. 1.268 to 1.269 at 15° C. ; boiling-point, 46° C. It may be ren- 
dered almost scentless by digestion with lime and then with copper 
turnings. Its possible impurities are dissolved sulphur, sulphur 
oils, and sulphuretted hydrogen. It is slightly soluble in water 
(about 1 in 400), forming a useful antiseptic fluid. 

ENACTIONS. 
Synthetical and Analytical Reactions. — 1. To a fragment of 
marble in a test-tube add water and then hydrochloric acid ; 
carbonic acid gas (C0 2 ) is evolved, and may be conveyed into 
water or solutions of salts by the usual delivery-tube. 

This is the process of the British Pharmacopoeia, and the one 
usually adopted for experimental purposes. On the large scale the 
gas is prepared from chalk or marble and sulphuric acid, frequent 
stirring promoting its escape. 

2. Pass the gas into lime-water ; a white precipitate of cal- 
cium carbonate (CaC0 3 ) falls. Solution of lead subacetate may 
be used instead of, and is perhaps even a more delicate test 
than, lime-water. 

The evolution of a gas on adding an acid to a salt, warming the 
mixture if necessary, the gas being inodorous and giving a white 
precipitate with lime-water, is sufficient evidence of the presence of 
-a carbonate. Carbonates in solutions of ammonia, potash, or soda 
may be detected by the direct addition of solution of lime. Car- 
bonates in presence of sulphites or hyposulphites may be detected 
by adding acid potassium tartrate, which decomposes carbonates 
with effervescence, but does not attack sulphites or hyposulphites. 

3. Blow air from the lungs through a glass-tube into lime- 
water ; the presence of carbonic acid gas is at once indicated. 

The passage of a considerable quantity of normal air through 
lime-water produces a similar effect. A bottle containing lime- 
water soon becomes coated with calcium carbonate from absorption 
of atmospheric carbonic acid gas. 

4. Fill a dry test-tube with the gas by passing the delivery- 
tube of the above apparatus to the bottom of the test-tube. 
Being rather more than once and a half as heavy as the air 
(1.529), it will displace the latter. Prove the presence of the 
gas by pouring it slowly, as if a visible liquid, into another 
test-tube containing lime-water; the characteristic cloudiness 
and precipitate are obtained on gently shaking the lime-water. 

In testing for carbonates by bringing evolved gas into contact 
with lime-water, the preparation and adaptation of a delivery-tube 



CARBONATES. 315 

may often be avoided by pouring the gas from the generating- tube 
into that containing the lime-water in the manner just indicated. 

5. Pass carbonic acid gas through lime-water until the pre- 
cipitate at first formed is dissolved. The resulting liquid is a 
solution of calcium carbonate in carbonic acid water. Boil the 
solution ; carbonic acid gas escapes, and the carbonate is again 
precipitated. 

This experiment will serve to show how chalk is kept in solution 
in ordinary well-waters, giving the property of " hardness," and 
how the/wr or stone-like deposit in tea-kettles and boilers is formed. 
It should be here stated that calcium sulphate produces similar 
hardness, and that these, with small quantities of magnesium sul- 
phate and carbonate, constitute the hardening constituents of well- 
waters, a curd (calcium or magnesium oleate) being formed whenever 
soap is used with such waters. An enormous amount of soap is wasted 
through the employment of hard water for washing purposes. The 
hardness produced by the earthy carbonates is termed " temporary 
hardness," because removable by ebullition ; that by the earthy 
sulphates, "permanent hardness," because unaffected by ebullition. 
The addition of lime-water or a mixture of lime and water removes 
temporary hardness (Reaction 2, p. 314), and sodium carbonate, 
"washing-soda," both temporary and permanent hardness, in the 
latter case sodium sulphate remaining in solution. Barium car- 
bonate (ground witherite) also decomposes calcium and magnesium 
sulphates, barium sulphate being precipitated and calcium or mag- 
nesium carbonates formed ; the latter and the carbonates originally 
in the water may then be precipitated by ebullition or by the action 
of lime-water. But the injurious effects of barium salts on man and 
the lower animals prevents the carbonate being used for purifying 
water for drinking purposes, as by accident or an unforeseen reac- 
tion a portion might become dissolved. 

6. Add a solution of potassium or sodium carbonate to a 
mercuric salt ; a brownish-red precipitate results. Add a solu- 
tion of potassium or sodium bicarbonate to a mercuric solution ; 
a white precipitate results, becoming red after some time. 



QUESTIONS AND EXERCISES. 

Name the chief natural carbonates. — What are the formulae of carbonic 
acid and carbonic acid gas ? — Adduce evidence of the existence of true 
carbonic acid. — Trace the steps by which the carbonic constituent of 
chalk is transferred to sodium by the two processes usually adopted in 
alkali-works — the manufacture of "soda." — Carbonic acid gas is con- 
stantly exhaled from the lungs of animals ; why does it not accumulate 
in the atmosphere? — What is the effect of pressure on carbonic acid gas? 
— State the specific gravity of carbonic acid gas ? — By what process may 
carbonic acid gas be obtained for experimental and manufacturing pur- 
poses? — Describe the action of carbonic acid gas on the potassium or 
sodium carbonate. — How may carbonic acid gas be detected in expired 



316 THE ACIDULOUS RADICALS. 

air? — To what extent is carbonic acid gas heavier than air? — Work sums 
showing what quantity of chalk (90 per cent, pure) will be required to 
furnish the carbonic acid gas necessary to convert 1 ton of potassium 
carbonate (containing 83 per cent, of K2CO3) into acid carbonate, suppos- 
ing no gas to be wasted. Ans. 1500 lbs.— Define " hardness " in water. — 
How may the presence of carbonates be demonstrated? 



OXALIC ACID AND OTHER OXALATES. 

Formula of Oxalic Acid, H 2 C 2 4 ,2II 2 or (COOH) 2 ,2H 2 0. Molecular 
weight, 126. 
Synonym. — Hydrogen Oxalate. 

Sources. — Oxalates occur in nature in the juices of some plants, 
as wood-sorrel, rhubarb, the common dock, and certain lichens, but 
the hydrogen oxalate (oxalic acid) and other oxalates are all made 
artificially. The carbon of many organic substances yields oxalic 
acid when those substances arc boiled with nitric acid, and an alka- 
line oxalate when they are roasted with a mixture of potassium 
and sodium hydrates. 

Experimental Process. — On the small scale a mixture of nitric 
acid 10 parts, loaf-sugar 2 parts, and water 3 parts quickly yields 
the acid. Abundance of red fumes are at first evolved. On cool- 
ing crystals are deposited. A more dilute acid, kept warm, acts 
more slowly, but yields a larger product. The following process is 
more economical : 

Manufacturing Process. — On the large scale sawdust is roasted 
with alkalies, resulting sodium oxalate decomposed by lime, with 
regeneration of the soda and formation of calcium oxalate, the 
latter digested with sulphuric acid, and the liberated oxalic acid 
(oxalic acid of commerce, B.P.) made commercially pure by recrys- 
tallization. 

Purified Oxalic Acid. — The acid made from sugar, recrystallized 
two or three times, is quite pure. Commercial acid should be mixed 
with insufficient water for complete solution, and the mixture occa- 
sionally shaken. Most of the impurities remain undissolved, and 
the saturated aqueous solution evaporated yields crystals which are 
fairly pure. 

Quant ivalcnce. — The elements represented by the formula C 2 4 
are those characteristic of oxalates. They form a bivalent grouping ; 
hence neutral oxalates (R / 2 C 2 4 ) and acid oxalates (R/HC 2 4 ) exist. 

Salt of Sorrel is a crystalline compound of oxalic acid with acid 
potassium oxalate, the crystals containing two molecules of water 
of crystallization (KHC 2 4 ,II 2 C 2 4 ,2H 2 0). 

Analytical Reactions (Tests). 
First Analytical Reaction, — To solution of an oxalate (ammo- 
nium oxalate, c. g.) add solution of calcium chloride ; a white 
precipitate falls (calcium oxalate, CaC 2 4 ). Add to the pre- 
cipitate excess of acetic acid ; it is insoluble. Add hydro- 
chloric acid ; the precipitate is dissolved. 



OXALATES. 317 

The formation of a white precipitate on adding a calcium or 
barium salt, insoluble in acetic but soluble in hydrochloric or nitric 
acid, is usually sufficient proof of the presence of an oxalate. The 
action of the liquid on litmus-paper, effervescence with sodium car- 
bonate, and absence of metals would indicate that the oxalate is 
that of hydrogen, oxalic acid. 

Note. — The barium oxalate is slightly soluble in acetic acid 
(Souchay and Lensscn), and enough may be dissolved by this acid 
from a mixed barium precipitate (produced on adding barium chloride 
or nitrate to a solution of mixed salts) to give the foregoing reaction 
on adding calcium chloride to the filtered acetic liquid — an effect 
sometimes useful in the analysis of mixed substances (Davies). 

Antidote. — In cases of poisoning by oxalic acid, or salt of sorrel, 
chalk and water may be administered as a chemical antidote (with 
the view of producing the insoluble calcium oxalate), emetics, and 
the stomach-pump or stomach-siphon being used as soon as possible. 

Second Analytical Reaction. — Heat a fragment of any dry 
common fixed metallic oxalate (a potassium oxalate, for exam- 
ple) in a test-tube ; decomposition occurs, carbonic oxide, CO 
(a gas that will be noticed subsequently) is liberated, and a 
carbonate of the metal remains. Add water and then an acid 
to the residue ; effervescence occurs. 

This is a ready test for ordinary insoluble oxalates, and is trust- 
worthy if, on heating the substance, no charring occurs, or not more 
than gives a gray color to the residue. Organic salts of metals de- 
compose when heated, and leave a residue of carbonate, but, except 
in the case of oxalates, the residue is always accompanied by much 
charcoal. Insoluble oxalates and organic salts of such metals as 
lead and silver are, of course, liable to be reduced to oxide or even 
metal by heat. Such oxalates may be decomposed by boiling with 
solution of sodium carbonate, filtering and testing the filtrate for 
oxalates by the calcium chloride test. 

Other Analytical Reactions. — Silver nitrate gives, with oxa- 
lates, a white precipitate (silver oxalate, Ag 2 C 2 4 ). Dry 

oxalates are decomposed when heated with strong sulphuric 
acid, carbonic oxide and carbonic acid gases escaping. If much 
of the substance be operated on, the gas may be washed with 
an alkali, the carbonic acid be thus removed, and the carbonic 
oxide be ignited ; it will be found to burn with a characteristic 
bluish flame. Oxalates, when mixed with water, black man- 
ganese oxide (free from carbonates), and sulphuric acid, yield 
carbonic acid gas, which may be tested by lime-water in the 

usual manner. Not only such insoluble oxalates as those of 

lead and silver above referred to, but any common insoluble 
oxalate, such as that of calcium or magnesium, may be decom- 
posed by ebullition with solution of sodium carbonate ; after 



318 THE ACIDULOUS RADICALS. 

filtration the oxalic radical will be found in the clear liquid as 
soluble sodium oxalate. 



QUESTIONS AND EXEECISES. 

Explain the constitution of oxalates. — State how oxalates are obtained. 
— What is the quantivalence of the oxalic radical? — Give the formula of 
" salt of sorrel." — Mention the chief test for oxalic acid and other soluble 
oxalates. — Name the antidote for oxalic acid, and describe its action. — 
By what reactions are insoluble oxalates recognized? 



TARTARIC ACID AND OTHER TARTRATES. 

Formula of Tartaric Acid, H 2 C 4 H 4 6 or C 2 H 2 (OH) 2 (COOH) 2 . Molecu- 
lar weight, 150. 

Synonym. — Hydrogen Tartrate. 

Sources. — Tartrates exist in the juice of many fruits, but it is 
from that of the grape that our supplies are usually obtained. 
Grape-juice contains much acid potassium tartrate (KHC 4 H 4 6 ), 
which is gradually deposited when the juice is fermented, as in 
making wine ; for acid potassium tartrate, not very soluble in aque- 
ous liquids, is still less so in spirituous, and hence crystallizes out 
as the sugar of the grape-juice is gradually converted into alcohol. 
It is found, with calcium tartrate, lining the vessels in which wine is 
kept ; and it is from this crude substance, termed argal or argol, 
also from the albumenoid yeasty matter or " lees" deposited at the 
same time, as well as from what tartrate may be remaining in the 
marc left after the juice has been pressed from the grapes, that by 
rough recrystallization " tartar," still containing 6 or 7 per cent, or 
more of anhydrous calcium tartrate (CaC 4 H 4 6 ), is obtained. From 
the tartar tartaric acid and other tartrates are prepared. In old 
dried grapes (raisins, Uvce, B. P.) crystalline masses of tartar and 
of grape-sugar are constantly met with. 

Cream of tartar, purified by crystallization (Potassii Bitartras, 
U. S. P.), occurs as "a gritty white powder or fragments of cakes 
crystallized on one surface ; " of a pleasant acid taste, soluble in 
180 parts of cold and 6 of boiling water, insoluble in spirit.* 

" If 1.2 grm. of potassium bitartrate be repeatedly agitated, during 
half an hour, with a mixture of 5 cc. of acetic acid and 1 cc. of 

'* A boiling solution of tartar yields a floating crust of minute crystals 
on cooling, just as milk yields a floating layer of cream ; hence the term 
cream of tartar. "It is called tartar" says Paracelsus, "'because it pro- 
duces oil, water, tincture, and salt, which burn the patient as Tartarus 
does." Tartarus is Latin (Taprapos, Tartaros, Greek) for hell. The prod- 
ucts of its destructive distillation are certainly somewhat irritating in 
taste and smell, and the "salt" (potassium carbonate) that is left is 
diuretic, and in larger quantities powerfully corrosive. 



TARTRATES. 319 

water, and the mixture be then diluted with 30 cc. of water and 
filtered, the clear filtrate should not be rendered turbid, within one 
minute, by the addition of 0.5 cc. of ammonium oxalate T. S. (limit 
of calcium salt)."— U. S. P. 

Quantivalence. — The elements represented by the formula C 4 H 4 6 
are those characteristic of tartrates. They form a bivalent grouping ; 
hence neutral tartrates (B/ 2 C 4 H 4 6 ) and acid tartrates (R/HC 4 H 4 6 ) 
exist. Potassium tartrate, the Potassii Tartras of the United States 
Pharmacopoeia (K 2 C 4 H 4 6 ), and Rochelle salt, or potassium and 
sodium tartrate, the official Potassii et Sodii Tartras, U. S. P. (Soda 
Tartrate, B. P.), are illustrations of neutral tartrates, while cream 
of tartar is an example of acid tartrates. The only official tartrate 
not apparently included in these general formulae is tartar emetic 
(Antimonium Tartar atum, B. P., Antimonii et Potassii Tartras, 
U. S. P.), which is sometimes regarded as the double tartrate of 
potassium and a hypothetical radical, antimonyl (SbO) ; thus, 
KSbOC 4 H 4 6 . Probably, however, it is but an antimony oxytartrate 
(Sb 2 2 C 4 H 4 6 ) with normal potassium tartrate (K 2 C 4 H 4 6 ) ; for there 
are several oxycompounds of antimony analogous to the oxycom- 
pounds of bismuth that have been described (p. 254), normal salts 
partially decomposed by water into oxides, and many of these oxy- 
compounds readily unite with normal salts of other basylous radicals. 
Tartar emetic would thus be antimony oxytartrate with potassium 
tartrate [Sb 2 2 C 4 H 4 6 ,K 2 C 4 H 4 6 or K/'St/'^CJ^O^'O"]. 

Tartaric Acid. 

Tartaric Acid, the Hydrogen Tartrate (Acidum Tartaricum, U. S. 
P.), is obtained, according to the British Pharmacopoeia, by boiling 
cream of tartar with water, adding chalk till effervescence ceases, 
and then calcium chloride so long as a precipitate falls ; the two 
portions of calcium tartrate thus consecutively formed are thoroughly 
washed, treated with sulphuric acid, the mixture boiled for a short 
time, resulting calcium sulphate mostly separated by filtration, the 
filtrate concentrated by evaporation, any calcium sulphate that may 
have deposited removed as before, and concentration continued until 
the solution is strong enough to crystallize. Calcium tartrate from 
9 ounces of cream of tartar requires 5 ounces by weight of sulphuric 
acid for complete decomposition. 



2KHC 4 H + O fi -f- CaC0 3 = CaC 4 H 4 6 

Acid potassium Calcium Calcium 
tartrate. carbonate. tartrate. 


+ K 2 C 4 H 3 6 + H 2 + CO, 

Potassium Water. Carbonic 
tartrate. acid gas. 


K 2 C 4 H 4 6 + CaCl 2 = 

Potassium Calcium 
tartrate. ~ chloride. 


CaC 4 H 4 6 + 2KC1 

Calcium Potassium 
tartrate. chloride. 


2CaC 4 H 4 6 + 2H 2 S0 4 = 

Calcitmi Sulphuric 
tartrate. acid. 


2CaS0 4 + 2H 2 C 4 H 4 6 

Calcium Tartaric 
sulphate. acid. 



Tartaric acid occurs in trade as colorless crystals or the same 
powdered. It is strongly acid and readily soluble in water or spirit. 



320 THE ACIDULOUS RADICALS. 

1 part in 8 of water and 2 of spirit of wine forms " Solution of Tar- 
taric Acid," B. P. Its aqueous solution is not stable. 

Parcels of tartaric acid often contain crystals of an allotropic or 
physically isomeric modification. (Vide " Allotropy" and " Isome- 
rism " in Index.) It is termed paratartaric acid (irapa, para, beside) 
or racemic acid (racemus, a bunch of grapes), and is a combination 
of ordinary tartaric acid, whose solution twists a ray of polarized 
light to the right hand (dextrotartaric or dextroracemic acid), and 
of lsevotartaric or lgevoracemic acid, whose solution twists a polarized 
ray to the left.* Racemic acid is inactive in this respect, the oppo- 
site properties of its constituents neutralizing each other. Racemic 
acid is less soluble in alcohol than tartaric acid. 

Reactions. 

Potassium Tartrate, or Tartrate of Potassium. 

Synthetical Reactions. — To a small quantity of a strong 
solution of potassium carbonate add acid potassium tartrate 
so long as effervescence occurs ; the resulting liquid is solu- 
tion of neutral potassium tartrate, Potassii Tartras, U. S. P. 
(K 2 C 4 H 4 6 ), crystals of which may be obtained on evaporation. 

Note. — This is a common method of converting an acid salt of a 
bivalent acidulous radical into a neutral salt. The carbonate added 
need not be a carbonate of the same, but may be of a different 
metal ; compounds like Rochelle salt (KNaC 4 H 4 6 ) are then obtained. 
Thus: 

Potassium and Sodium Tartrate. 

Synonyms. — Tartrate of Potassium and Sodium 5 Tartrate of Pot- 
ash and Soda 5 Rochelle Salt. 

To a strong hot solution of sodium carbonate add acid potas- 
sium tartrate until effervescence ceases ; the resulting liquid is 
solution of potassium and sodium tartrate : on cooling it yields 
crystals. This is the official process (Soda Tartarata, B. P. ; 
Potassii et Sodii Tartras, U. S. P.) (KNaC 4 H 4 6 ,4H 2 0). 

Na 2 C0 3 + 2KHC 4 H 4 6 = 2KNaC 4 H 4 6 + H 2 4- C0 2 

Sodium Acid potassium Potassium and Water. Carbonic 

carbonate. tartrate. sodium tartrate. • acid gas. 

Crystals of Rochelle salt are usually halves of colorless transpa- 
rent right rhombic prisms, slightly efflorescent in dry air, soluble 
in 5 parts of boiling water. Potassium tartrate is slightly deliques- 
cent, soluble in about 4 parts of boiling water. 

* According to Van 't Hoff and Le Bel, all compounds that cause such 
rotation contain at least one atom of carbon with which is united four 
different atoms or radicals. Such carbon atoms are conveniently termed 
asymmetrical. 



TARTRATES. 



321 



Equivalent Weights of Tartaric Acid, Potassium Carbonate, Potas- 
sium Bicarbonate, Sodium Carbonate (crystallized), Sodium 
Bicarbonate, and Ammonium and Magnesium Carbonates repeated 
for 20 parts of each (and, incidentally, for other proportions). 



Tart, acid . 
Potas. carb. 
Pot. bicarb. 
Sod. carb. . 
Sod. bicarb. 
Amnion, carb 
Magnes. carb 



H 2 C 4 H 4 6 =150 

K 2 C0 3 (of 84 per cent.) . . =164 

2(KHC0 3 ) . =200 

Na 2 CO 3 ,10H 2 O =286 

2(NaHC0 3 ) =168 

(N a H 11 C,0 6 )-s-3X2 . . . .=105 
(MgC0 3 ) 3 Mg2HO,4H 2 0-^4 =95.5 



20 


18J 


15 


10* 


171 


28* 


22 


20 


16* 


11* 


19* 


31* 


26| 


24* 


20 


14 


23| 


38J 


38 


34| 


28* 


20 


34 


54* 


22* 


20i 


16f 


Hi 


20 


32 


14 


12| 


10* 


U 


12* 


20 


12| 


11* 


n 


6| 


Hi 


18J 



31* 

34* 

42 

60 

35i 

21£ 

20 



Thus 20 parts (grains or other weights) of tartaric acid neutralize 
22 of potassium carbonate, 26f of potassium bicarbonate, 38 of 
sodium carbonate, 22J of sodium bicarbonate, 14 of ammonium 
carbonate, or 12| of magnesium carbonate. Other quantities of 
tartaric acid (18£, 15, 10J, 17f, 28^, 31 J) saturate the amount 
of salts mentioned in the other columns, and vice versa. A similar 
table for citric acid will be found at p. 325, and for both acids in 
the Appendix. These tables afford good illustrations of both of the 
laws of chemical combination (pp. 47, 198). The reader should 
verify a few of the numbers by calculation from the atomic weights 
of the elements concerned in the reactions, remembering that the 
salts formed are considered to be neutral in constitution. In medi- 
cal practice effervescing saline draughts are often designedly pre- 
scribed to contain an amount of acid or alkali considerably in excess 
of the proportions required for perfect neutrality. 

Effervescent Tartar ated Soda Powder (Pidvis Sodce Tartar atoe 
Effervescens, B. P.), or Seidlitz Powder, consists of 3 parts of 
Rochelle salt (120 grains), with 1 part (40 grains) of acid -sodium 
carbonate (the mixture usually wrapped in blue paper), and 1 part 
(38 grains) of tartaric acid (wrapped in white paper). When 
administered, one powder is dissolved in a tumbler rather more 
than half full of water, the other added, and the mixture drunk 
during effervescence. It will be seen that the salts swallowed are 
potassium and sodium tartrate (KNaC 4 H 4 6 ,4H 2 0), sodium tartrate 
(Na 2 C 4 H 4 6 ,2H 2 0), and acid sodium or potassium tartrate. The 
last-mentioned salt results because, for one reason, 1\ grains of the 
tartaric acid is in excess of the quantity necessary for the formation 
of neutral sodium tartrate ; and, for another reason, because while 
carbonic acid remains in great excess, a neutral tartrate containing 
potassium may be converted more or less into acid potassium tar- 
trate and a bicarbonate. This amount of acid salt gives, according 
to the taste of some persons, agreeable acidity to the draught. The 
United States formula (Pulvis Effervescens Compositus, U. S. P.) 
includes rather less tartaric acid, so that only neutral salts are 
formed, and the occurrence of the gritty acid potassium tartrate 



322 THE ACIDULOUS RADICALS. 

avoided. " Double " Seidlitz powders contain a double dose of 
Rochelle salt. 

Analytical Reactions (Tests). 

First Analytical Reaction. — To solution of any normal tar- 
trate, or tartaric acid made neutral by solution of soda, add 
solution of calcium chloride ; a white precipitate (calcium tar- 
trate, CaC 4 H 4 6 ,4H 2 0) falls. Collect the precipitate on a filter, 
wash, place a small quantity in a test-tube, and add solution of 
potash : on stirring the mixture the precipitate dissolves. Heat 
the solution : calcium tartrate is again precipitated. 

In this reaction a fair amount of the calcium chloride solution 
should be added at once, and the test be performed without delay, 
or the calcium tartrate will assume a crystalline character and be 
with difficulty dissolved by the potash. The potash should be quite 
free from carbonate. 

The solubility of calcium tartrate in cold potash solution enables 
the analyst to distinguish between tartrates and citrates, otherwise 
a difficult matter. Calcium citrate is not soluble, or only to a very 
slight extent, in the alkali. The absence of much ammoniacal salt 
must be ensured, calcium citrate as well as tartrate being soluble in 
solutions of salts of ammonium. 

Second Analytical Reaction. — Acidulate a solution of a tar- 
trate with acetic acid, add potassium acetate, and well stir the 
mixture ; a crystalline precipitate (acid potassium tartrate) 
slowly separates. 

This reaction is not applicable in testing for very small quantities 
of tartrates, the acid potassium tartrate being not altogether insol- 
uble. The precipitate being insoluble in alcohol, however, the 
addition of spirit of wine renders the test far more delicate. 

Third Analytical Reaction. — To a neutral solution of a tar- 
trate add solution of silver nitrate ; a white precipitate (silver 
tartrate, Ag 2 C 4 H 4 6 ) falls. Boil the mixture ; it blackens, 
owing to the reduction of the salt to metallic silver. Or, before 
boiling, add a drop or less of ammonia ; a mirror will form on 
the tube, adhering well to the glass if the tube was thoroughly 
cleansed. Even an insoluble tartrate, placed in a dry tube 
with a few fragments of silver nitrate and a drop or less of 
ammonia added, gives a mirror-like character to each fragment 
of silver salt when the tube is gently rotated some inches 
above a flame. 

Other Reactions. — Tartrates heated with strong sulphuric 
acid char immediately. Tartaric acid and the soluble tar- 
trates prevent the precipitation of ferric and other hydrates by 
alkalies, solutions of double tartrates being formed (which on 



CITRATES. 323 

evaporation yield liquids that do not crystallize, but, spread on 
sheets of glass, dry up to thin transparent plates or scales). 
The iron potassio-tartrate {Ferri et Potassii Tartras, U. S. P. ; 

Ferrum Tartaratum B. P.) is a preparation of this kind. 

Tartrates decompose when heated, carbonates being formed and 
carbon set free, the gaseous products having a peculiar more or 
less characteristic smell resembling that of burnt sugar. 



QUESTIONS AND EXERCISES. 

State the origin of tartaric acid and other tartrates, and explain the 
deposition of argol, crude acid potassium tartrate, during the manufacture 
of wine. — What is the chemical formula, and what are the characters, of 
"cream of tartar"? — Mention the formula and quantivalence of the tar- 
taric radical.— Write formula? of various tartrates, including tartar emetic. 
—Give equations or diagrams illustrative of the production of tartaric 
acid from cream of tartar. — By what general process may normal or 
double tartrates be obtained from acid potassium tartrate? — Workout 
sums proving the correctness of some of the figures given on p. 321 as 
showing the saturating power of tartaric acid for various quantities of 
different carbonates, and give diagrams or equations of the reactions. — 
State the names and work sums showing quantities of the salts resulting 
from the admixture of 120 grains of potassium and sodium tartrate, 40 
grains of acid sodium carbonate, and 38 grains of tartaric acid (Seidlitz 
powder). — Enumerate the tests for tartrates, and explain the effect of 
heat on tartrates of the metals. 



CITRIC ACID AND OTHER CITRATES. 

Formula of Citric Acid, H 3 C 6 H 5 7 ,H 2 0. Molecular weight, 210. 
Synonym. — Hydrogen Citrate. 

Source. — Citric acid {Acidum Citricum, V. S. P.) exists in the 
juice of the gooseberry, currant, cherry, strawberry, raspberry 
(Rubus Idceus, U. S. P.), and many other fruits, as well as in other 
parts of plants. The pulp of the fruit of Tamarindus indica 
(Tamarindus, U. S. P.) contains from 1 to 12 per cent, (in addition 
to 1.5 of tartaric acid, .5 of malic acid, and 3 per cent, of acid 
potassium tartrate). But it is from the lemon or lime that the 
acid of commerce is usually obtained. For this purpose concen- 
trated lemon-juice is exported from Sicily, concentrated bergamot- 
juice from the Calabrian coast of South Italy, and concentrated 
lime-juice from the West Indies. The lime-fruit from Citrus berga- 
mia is official in the Pharmacopoeia of India. 

Process. — The British Pharmacopoeia directs that the hot lemon- 
juice (4 pints) be saturated by powdered chalk — that is, whiting — 
(4J ounces), the resulting calcium citrate collected on a filter, washed 
with hot water till the liquor passes from it colorless (by which 
not only the coloring matter, but the mucilage, sugar, and other 
constituents of the juice, is got rid of), then mixed with cold water 
(1 pint), decomposed by sulphuric acid (2$ fluidounces in 1 J pints 



324 THE ACIDULOUS RADICALS. 

of water), the mixture boiled for half an hour, filtered, the solu- 
tion evaporated to a density of 1.21, set aside for twenty-four 
hours, then poured off from any deposit of crystalline calcium sul- 
phate, further concentrated, and set aside to crystallize. If the 
quantity of calcium citrate to be decomposed is indefinite, the sul- 
phuric acid may be added until a little of the supernatant fluid 
gives, after a minute or two, a precipitate with solution of calcium 
chloride. The concentrated citric solution generally crystallizes 
very slowly. Shaken violently, however, in a bottle with a granule 
or two of solid acid, it quickly yields its citric acid in a pulverulent 
form, and this, drained and redissolved in a very small quantity of 
hot water, yields crystals fairly quickly (Warington). 
2H 3 C 6 H 5 7 + 3CaC0 3 = Ca 3 2C 6 H 5 7 + 3H 2 + 3C0 2 

Citric acid Calcium Calcium Water. Carbonic 

(impure). carbonate. citrate. acid gas. 

Ca 3 2C 6 H 5 7 + 3H 2 S0 4 = 2H 3 C 6 H 5 7 -f 3CaS0 4 

Calcium Sulphuric Citric acid Calcium 

citrate. acid. (pure). sulphate. 

Quantivalence. — The elements represented by the formula C 6 H 5 7 
are those characteristic of citrates. They form a trivalent grouping ■ 
hence three classes of salts may exist — one, two, or three atoms of 
the basylous hydrogen in one molecule of the acid, H 3 C 6 H 5 7 , being 
displaced by equivalent proportions of other basylous radicals. 
Constitutional formula, C 3 H 4 (OH)(COOH) 3 . 

Citric acid itself is the only citric compound of much direct 
importance to the pharmacist. It usually occurs in colorless crys- 
tals soluble in half their weight of boiling and three-fourths of cold 
water, less soluble in spirit, and insoluble in ether. A solution of 
36 to 46 grains in 1 ounce of water forms a sort of artificial lemon- 
juice. Citrates heated with strong sulphuric acid to about 215° F. 
evolve carbonic oxide gas, and at higher temperatures acetone and 
carbonic acid gas. 

The artificial production of citric acid has been accomplished by 
Grimaux and Adam, who, starting with glycerin, produce certain 
chloro- and cyano-derivatives, and ultimately citric acid itself. 

Action of Heat on Citric Acid. — Citric acid, slowly heated, first 
loses its water of crystallization ; afterward (347° F.) the elements 
of another molecule of water are evolved, and a residue obtained 
from which ether extracts aconitic acid, H 3 C 6 H 3 O e , identical with 
the aconitic acid (and the acid first termed equisetic) in various spe- 
cies of Aconitum and Equisetum. 

The official lemon-juice (Limonis Succus, U. S. P.) is to be freshly 
expressed from the ripe fruit, have a specific gravity not less than 
1.030, and contain about 7 per cent, of citric acid (H 3 C 6 H 5 7 ,H 2 0). 
The acidity may be ascertained by adding solution of potash or 
soda (the strength of which has been determined previously with 
pure crystals of citric acid) till red litmus-paper is fairly turned 
blue. Before applying this test to commercial specimens of lemon- 
juice the absence of notable quantities of sulphuric, hydrochloric, 
acetic, tartaric, or other acid must be ensured by application of 
appropriate reagents. (See also "Lemon-juice," in Index.) 



CITRATES. 



325 



Lime-juice as imported into England contains an average of 7.84 
per cent, of citric acid, rarely rising to 10 per cent, and very seldom 
falling to 7 per cent. Containing but little sugar and mucilage, it 
requires no addition of spirit to preserve it. Lemon-juice requires 
about 40 per cent, of proof spirit to prevent fermentation (Conroy). 

Equivalent Weights of Citric Acid, Potassium Carbonate, Potas- 
sium Bicarbonate, Sodium Carbonate, {crystallized), Sodium Bi- 
carbonate, and Ammonium and Magnesium Carbonates repeated for 
rts of each (and, incidentally, for other proportions). 



Citric acid, 
Pot. carb., . 
Pot. bicarb., 
Sod. carb., . 
Sod. bicarb., 
Amm. carb. 
Mag.carb., . 



H 3 C 6 H 5 7 ,H a O =210 

(K 2 C0 3 ; of 84 per cent.) -- 2 X 3=246£ 

3(KHC0 3 ) =300 

(Na 2 C0 3 ; 10H 2 O) -5-2X3 . . .=429 

3(NaHC0 3 ) =25B 

(N 3 H 11 C a 6 ) =157 

(MgC0 3 ) 3 Mg2HO,4H 2 -4-8X3 =143 



20 


17 


14 


n 


1G| 


26| 


23J 


20 


16£ 


U\ 


19| 


3H 


28* 


24J 


20 


14 


24 


38J 


41 


34j 


28J 


20 


34 


54^ 


24 


20£ 


16| 


HI 


20 


32 


15 


12j 


10£ 


7i 


m 


20 


13£ 


11| 


9* 


6f 


iii 


m 



29i 

S4i 

41| 

60 

35 

21| 

20 



Thus 20 parts (grains or other weights) of citric acid neutralize 23 J 
of potassium carbonate, 28 £ of potassium bicarbonate, 41 of sodium 
carbonate, 24 of sodium bicarbonate, 1 5 of ammonium carbonate, or 
13 J of magnesium carbonate. Other quantities of citric acid (17, 
14, 9|, 16f , 26f , 29£) saturate the amounts of salts mentioned in 
the other columns, and vice versa. 

This table, the similar one for tartaric acid (p. 321), and that for 
both acids {vide Appendix) afford good illustrations of both of the 
laws of chemical combination (pp. 47, 198). The reader should 
verify a few of the numbers by calculation from the atomic weights 
of the elements concerned in the reactions, remembering that the 
salts formed are considered to be neutral in constitution. In medical 
practice effervescing saline draughts are often designedly prescribed 
to contain an amount of acid or alkali considerably in excess of the 
proportions required for perfect neutrality. 

Analytical Reactions (Tests). 

First Analytical Reaction. — To a dilute solution of any 
neutral citrate, or citric acid carefully neutralized by alkali, 
add solution of calcium chloride and boil ; a white precipitate 
(calcium citrate, Ca 3 2C G H 5 7 ) falls. Treat the precipitate as 
for calcium tartrate (p. 322) ; it is not perceptibly dissolved by 
the potash. 

A mixture of citrates and tartrates can be separated by this re- 
action. They are precipitated as calcium salts, and the rapidly 
washed precipitate mixed with solution of potash, diluted and 
filtered : the filtrate contains the tartrate, which is shown to be 
15 



326 THE ACIDULOUS RADICALS. 

present by reprecipitation on boiling. The precipitate still on the 
filter is washed, dissolved in solution of ammonium chloride, and 
the solution boiled 5 the calcium citrate is reprecipitated. The pres- 
ence of much sugar interferes with this reaction. A dilute solution 
of a citrate is not precipitated by calcium chloride until the liquid is 
heated : precipitation from a strong solution, also, is not thoroughly 
complete without ebullition of the mixture. This reaction is not 
thoroughly satisfactory, calcium citrate being slightly soluble in 
alkalies, in the solutions of salts produced in the reaction, and to 
a very slight extent even in cold water. It is readily soluble in 
acetic acid. 

Second Analytical Reaction. — To a neutral solution of a 
citrate add solution of silver nitrate ; a white precipitate (silver 
citrate, Ag 3 C 6 H 5 7 ) falls. Boil the mixture ; the precipitate does 
not blacken as silver tartrate does, or only after long boiling. 

Other Analytical Reactions. — Citric acid forms no precipitate 

corresponding with the acid potassium tartate. Lime-water, 

in excess, gives no precipitate with citric acid or citrates unless 
the solution is boiled, calcium citrate being slightly soluble in 
cold, but not in hot, water ; it usually precipitates tartrates in 

the cold. Citrates when heated with strong sulphuric acid 

do not char immediately. Citric acid and citrates prevent 

the usual precipitation of iron by alkalies, soluble double com- 
pounds being formed. The Ferri et Ammonii Citras, U. S. P., 

is a preparation of this kind. Metallic citrates decompose 

when heated, carbonates being formed and carbon set free ; the 
odor of the gaseous products is not so characteristic as that of 

tartrates. According to Cailletet, a cold saturated solution 

of red potassium chromate turns a solution of tartaric acid 
dark brown, carbonic acid gas being evolved, while a solution 
of citric acid only slowly becomes of a light brown. 

PuscTi's test for the detection of tartaric acid in citric acid depends 
on the well-known difference in the action of sulphuric acid on tar- 
taric acid and on citric acid. It consists in adding to 1 gramme 
of powdered citric acid in a dry test-tube 10 grammes of strong 
pure (colorless) sulphuric acid, and keeping the part of the tube 
containing the mixture immersed in boiling water for an hour. The 
citric acid dissolves with evolution of gas and frothing to form a 
lemon-colored liquid, and if the sample be pure this color undergoes 
no change within half an hour ; but if as much as J per cent, of 
tartaric acid be present, the lemon color becomes brownish within 
that time, and in an hour the mixture is red-brown. 






QUESTIONS AND EXEECISES. 

What is the source of citric acid ? — Describe the preparation of citric 
acid, giving diagrams. — Illustrate by formulae the various classes of tar- 



PHOSPHATES. 327 

trates and citrates. — State the average proportion of citric acid in lemon- 
juice. — Work out sums proving the correctness of some of the figures 
given on p. 325, as showing the saturating power of citric acid for various 
carbonates. — What are the tests for citrates? — How are tartrates sepa- 
rated from citrates ? 



PHOSPHORIC ACID AND OTHER PHOSPHATES. 

Formula of the Acid, H 3 P0 4 or PO(OH) 3 . Molecular weight, 98. 
Synonym. — Hydrogen Phosphate. 

Source. — The source of the ordinary normal phosphates and of 
phosphorus itself [Phosphorus, U. S. P.) is the normal calcium phos- 
phate (Ca 3 2P0 4 ). It is the chief constituent of the bones and teeth 
of animals, being derived from the plants on which they feed, plants 
again obtaining it from the soil. Compounds of phosphorus are 
also met with in the brain, nerves, muscles, blood, saliva, and, 
according to Kirkes, even in tissues so simple that one must assume 
that the compounds are necessary constituents of the substance of 
the primary cell. They escape from the system both in the urine 
and in the faeces. 

Process. — Phosphorus (P = 31) is obtained from bones by the fol- 
lowing processes : The bones are burnt to remove all traces of animal 
matter. The resulting bone-earth is treated with hot and fairly 
strong sulphuric acid, by which phosphoric acid and calcium sulphate 
are produced: 

Ca 3 2P0 4 + 3H 2 S0 4 = 2H 3 P0 4 + 3CaS0 4 . 

The acid fluid, strained from the sulphate and concentrated, is 
mixed with charcoal, coke, or sawdust and dried in an iron pot. 
At this stage water escapes and metaphosphoric acid remains : 

2H 3 P0 4 = 2HP0 3 -f 2H 2 0. 

The mixture is the** to be transferred to a fireclay retort and 
strongly heated ; phosphorus vapor is evolved and is condensed under 
water : 

4HP0 3 + C 12 = 2H 2 + 12CO + P 4 . 

The phosphorus is purified by melting under water containing sul- 
phuric acid and red potassium ehromate, and is filtered through can- 
vas and cast into sticks. 

Properties. — Phosphorus is "a semi-transparent, colorless, wax- 
like solid (in sticks or cakes), which emits white vapors when ex- 
posed to the air. Specific gravity, 1.77. It is soft and flexible at 
common temperatures, melts at 110° F., ignites in the air at a tem- 
perature a little above its melting-point, burning with a luminous 
flame and producing dense white fumes. It is very poisonous. In- 
soluble in water, but soluble in ether and in boiling oil of turpen- 



328 THE ACIDULOUS RADICALS. 

tine, also in carbon bisulphide. It is soluble in oil which has been 
previously heated for a short time to about 300° F. to expel moisture 
— 1 part in 90 of dried almond oil constituting phosphorated oil 
( Oleum Phosphoratum, U. S. P.). A mixture, or rather a solution, of 
phosphorus in chloroform, mixed with althea, acacia, glycerin, coated 
with balsam of Tolu (previously dissolved in ether), forms the official 
phosphorus pills (Pilulce Phosphoric U. S. P.)." 

Granulated or pulverulent phosphorus is obtained by placing a 
portion under equal parts of spirit and water in a bottle, standing 
the bottle in warm water till the phosphorus melts, then inserting 
the stopper (glass, not cork), and shaking the whole till cold. 

Red or Amorphous Phosphorus. — Ordinary phosphorus kept at a 
temperature of about 450° F. in an atmosphere from which air is 
excluded becomes red, opaque, insoluble in liquids in which ordinary 
phosphorus is soluble, oxidizes extremely slowly, and only ignites 
when heated to near 500° F. It is used in the manufacture of sev- 
eral varieties of lucifer-matches, not emitting the poisonous jaw- 
destroying fumes given off by ordinary phosphorus. 

Quantivalence. — The atom of phosphorus is quinquivalent, as 
seen in the pentachloride (PC1 5 ) and oxychloride (POCl 3 ) ; but it 
often exhibits trivalent activity, as seen in the trichloride (PC1 3 ) and 
trihydride (PH 3 ). 

Zinc Phosphide, Zn 3 P 2 (Zinci Phosphidum, U. S. P.), occurs as 
a grayish-black powder or in crystalline fragments having a metal- 
lic lustre. It may be obtained by throwing phosphorus upon melted 
zinc. 

Molecular Weight. — Phosphorus is an exception to, the rule that 
the atomic weights (in grains, grammes, etc.) of elements occupy 
similar volumes of vapor at similar temperatures, the equivalent 
weight of phosphorus (31) only giving half such a volume. Hence, 
while the molecular weights — that is, double the atomic weights — 
of oxygen (0 2 = 32), hydrogen (H 2 = 2), nitrogen (N 2 = 28), etc., 
give a similar bulk of vapor at any given temperature, the double 
atomic weight of phosphorus (P 2 = 62) only gives half this bulk ; 
that is, four times the atomic weight of phosphorus must be taken 
to obtain the whole bulk. It would appear, therefore, that the 
molecule of phosphorus contains four atoms, P 4 = 124. As with 
sulphur, however, phosphorus in the state ordinarily known to us 
may be abnormal, and conditions yet be found in which the mo- 
lecular weight is double the atomic weight. 

Phosphoric Acid. 

Synonyms. — Orthophosphoric Acid ; Hydrogen Phosphate. 

The chief use of phosphorus in pharmacy is for the produc- 
tion of diluted phosphoric acid. Phosphorus is boiled with 
nitric acid and water until dissolved. The solution, evaporated 
to a low bulk to remove nitrous compounds, and diluted so as 
to contain 85 per cent, of acid (H 3 P0 4 ), constitutes the Acidum 
Phosphoricum, U. S. P., a colorless liquid of specific gravity 



PHOSPHATES. 329 

1.710. The latter, diluted so as to contain 10 per cent, of the 
acid, constitutes the Acidum JPhosphoricum Dilutum, U. S. P., 
a colorless, sour liquid of specific gravity 1.057. If the neces- 
sary appliances are at hand, specimens may be prepared by the 
official process as follows : f of an ounce of the concentrated, 
or a 1 pint of the diluted, is made by boiling together, in a 
flask attached to a vertical condenser, 103 grains of phosphorus, 
1| fluidounces of the official nitric acid, and 2 ounces of water. 
By some such arrangement the condensed products are returned 
to the flask. The operation is continued until the phosphorus 
has disappeared. 

3P 4 + 20HNO 3 + 8H 2 = 12H 3 P0 4 + 20NO 

Phosphorus. Nitric acid. Water. Phosphoric acid. Nitric oxide. 

The liquid remaining in the flask is then transferred to a dish 
(preferably of platinum), evaporated down to about J an ounce, 
and, lastly, diluted with distilled water. 

The use of the water in the former part of the process is to mod- 
erate the reaction. Strong hot nitric acid oxidizes phosphorus with 
almost explosive rapidity ; hence the acid must be diluted in the 
first instance, and the dilution be maintained to prevent its becom- 
ing too strong by loss of water. Time is saved by using a strong 
acid, but in that case constant supervision is necessary, in order that 
water may be added or the temperature otherwise reduced should 
the action become too violent. Deficiency of nitric acid must also 
be avoided, or some phosphorous acid (H 2 PH0 3 ) will be formed. 

Markoe, also to economize time, modifies the process by adding 
for every ounce of phosphorus 4 or 5 grains of iodine, and, drop by 
drop, 25 or 30 drops of bromine. The iodine and bromine unite 
with the phosphorus with a readiness, or even violence, that would 
be explosive if not controlled by the presence of the cold fluids — 
further cooled, if necessary, by immersing the vessel in cold water. 
Phosphorus iodide (PI 5 ) and phosphorus bromide (PBr 5 ) are at once 
formed. These in the presence of water immediately yield hydriodic 
and hydrobromic acids (HI, HBr) and phosphoric acid. The nitric 
acid attacks the hydriodic and hydrobromic acids, forming the lower 
oxides of nitrogen, which escape as gas, water, and free iodine and 
bromine. The latter unite with more phosphorus, and the reactions 
are repeated. This carrying power of a little iodine or bromine or 
both would perhaps be indefinitely prolonged if no vapor of these 
elements or their acids escaped with the gases. The phosphorus 
having disappeared, excess of nitric acid is got rid of roughly by 
dropping in clean rags or paper (nitric oxide, carbonic acid gas, and 
water being formed), and the last portions by adding oxalic acid 
(which even still more readily yields similar products). Evapora- 
tion to a syrupy consistence finally removes all traces of iodine, 
bromine, oxalic acid, and moisture. The product is then diluted to 
any required extent. 



330 



THE ACIDULOUS RADICALS. 




Experimental Process. — A flask, in the neck of which a funnel is 
inserted and a second funnel inverted, so 
Fig. 40. that its mouth rests within the mouth of 

the first, is an efficient and convenient ar- 
rangement of apparatus for the official 
process, especially if the operation be con- 
ducted slowly. (See Fig. 40.) 

Solution of phosphoric acid evaporated 
to a sp. gr. of 1.850 yields a mass of pris- 
matic crystals of H 3 P0 4 , especially if a 
crystal or two be dropped into the fluid 
(Cooper). Further evaporated, it leaves a 
residue which melts at a low red heat, 
yielding pyrophosphoric acid, and, finally, 
metaphosphoric acid (Glacial Phosphoric 
Acid). 

A commercial variety of phosphoric acid, 
containing no large amount of impurity, 
is prepared by well digesting a mixture of 
bone-ash, sulphuric acid, and water, filtering, concentrating, precip- 
itating calcium by strong sulphuric acid, and heating until sulphuric 
vapors cease to escape ; also by burning phosphorus to phosphoric 
anhydride, dissolving the latter in water, and boiling with a little 
nitric acid to oxidize any lower acids of phosphorus and to cause 
any meta- or pyro-phosphoric acid to take up the elements of water. 
Prepared from bones, phosphoric acid is apt to develop fungoid 
deposit (Jensen). Prepared from ' phosphorus, it occasionally con- 
tains arsenum in the form of arsenic acid. The latter is detected 
and removed, together with any traces of platinum or lead, on pass- 
ing sulphuretted hydrogen through the warmed acid. 

Quantivalence. — The elements represented by the formula P0 4 
are those characteristic of phosphates. The grouping is trivalent 5 
hence there may exist trimetallic phosphates (M / 3 P0 4 ). dimetallic 
acid phosphates (M' 2 HP0 4 ), or monometallic acid phosphates 
(M / H 2 P0 4 ), and, lastly, trihydric phosphate (H 3 P0 4 ), or common 
phosphoric acid. These are the ordinary phosphates, or orthophos- 
phates, met with in nature or used in pharmacy ; the rarer pyro- 
phosphates and metaphosphates, as well as the phosphites and 
hypophosphites, will be mentioned subsequently. Crude dry 
calcium phosphate ground with sulphuric acid yields the very 
largely used artificial manure termed " superphosphate." It con- 
tains acid calcium phosphate (CaH 4 2P0 4 ,2H 2 0) and calcium phos- 
phate (CaS0 4 ,2H 2 0). 

Analytical Reactions (Tests). 

First Analytical Reaction. — To an aqueous solution of a 
phosphate (e. g. Na 2 HP0 4 ) add solution of magnesium sulphate 
with which ammonium chloride and ammonia have been mixed ; 
a white crystalline precipitate falls (ammonio-magnesian phos- 
phate, MgNH 4 P0 4 ). 



PHOSPHATES. 331 

Ammonium chloride is added to prevent the precipitation of 
magnesium hydrate. Arsenates, which have close analogy to 
phosphates, give with the magnesium reagent a precipitate of sim- 
ilar character. 

Second Analytical Reaction. — To an aqueous solution of a 
phosphate add solution of silver nitrate ; light yellow silver 
phosphate (Ag 3 P0 4 ) is precipitated — completely, if the mix- 
ture be neither acid nor alkaline. To a portion of the precipi- 
tate add ammonia ; it dissolves. To another portion add nitric 
acid ; it dissolves. By the former part of this reaction phos- 
phates may be distinguished from their close allies the arsen- 
ates, silver arsenate being of a chocolate color. 

Third Analytical Reaction. — To a solution (in a few drops 
of acid) of a phosphate insoluble in water (e. g. Ca 3 2P0 4 ) add 
the acetate of an alkali-metal (easily made by adding to soda 
or ammonia in a test-tube excess of acetic acid), and then a 
drop or two of solution of ferric chloride ; a yellowish-white 
precipitate falls (ferric phosphate, Fe 2 2P0 4 ), insoluble in acetic 
acid. Too much of the ferric chloride must not be added or ferric 
acetate will be produced, in which the ferric phosphate is to 
some extent soluble. 

To remove the whole of the phosphoric radical from the solu- 
tion add ferric chloride so long as a precipitate is produced, and 
boil ; ferric phosphate and oxyacetate are precipitated. 

To obtain confirmatory evidence of the presence of phosphate 
in this precipitate, and to separate the phosphoric radical as a 
more characteristic phosphate, collect the precipitate on a filter, 
wash, drop some solution of ammonia on it, then ammonium 
sulphydrate, and finally wash with water ; black ferrous sul- 
phide remains on the filter, while ammonium phosphate occurs 
in the filtrate. To the filtrate add a mixture of solutions of 
magnesium sulphate and ammonium chloride, and well stir ; a 
granular precipitate (ammonio-magnesian phosphate) appears. 

Fourth Analytical Reaction.— In diluted nitric acid dissolve 
a little calcium phosphate (or any other phosphate), and then 
add solution of ammonium molybdate, and gently heat ; a yel- 
low precipitate falls. 

This precipitate contains what is somewhat indefinitely termed 
phospho-molybdic acid — a compound of molybdic acid with phos- 
phoric acid (about 4 per cent, of H 3 P0 4 ) with ammonia (nearly 7 
per cent.). 

Ammonium molybdate is obtained by roasting native molyb- 
denum sulphide (MoS.„ U. S. P. ; (NH 4 ) 2 Mo0 4 )— which much resem- 
bles lead ; hence the name of the metal, from judivfidos, molubdos, lead — 
to molybdic oxide or anhydride (Mo0 3 ), dissolving the latter in water, 
adding ammonia, evaporating, and crystallizing. 



332 THE ACIDULOUS RADICALS. 

Molybdates having the following formulae (M = 1 univalent atom 
of any metal) have been obtained : M 2 Mo0 4 ; MHMo0 4 ; MHMo0 4; - 
H 2 Mo0 4 . According to Carington, commercial ammonium molyb- 
date is commonly the intermediate of the three salts. 

Note. — The foregoing two reactions are useful in the analysis of 
bone-earth, of other earthy iron phosphate, and all phosphates in-. 
soluble in water. Only arsenates give similar appearances, but the 
acid solution of these may be decomposed by agitation with sulphur- 
ous acid, ebullition, and subsequent treatment with sulphuretted 
hydrogen — yellow arsenous sulphide, As 2 S 3 , being then precip- 
itated. 

Other Analytical Reactions. — Solutions of barium and cal- 
cium salts give, with aqueous solutions of phosphates, white 
precipitates (of the respective phosphates BaHP0 4 or Ba 3 - 
2P0 4 , and CaHP0 4 or Ca 3 2P0 4 ), all of which are soluble in 
acetic and the stronger acids ; lead acetate a white precipitate. 



QUESTIONS AND EXERCISES. 

State the source of phosphorus. — Give equations or diagrams explana- 
tory of the isolation of phosphorus from its natural compounds. — What 
is the composition of farmers' " superphosphate," and how is it prepared ? 
Enumerate the properties of phosphorus. — Mention some solvents of 
phosphorus. — How are the official varieties of phosphoric acid made? 
Describe the precautions to be observed in making this acid. — What are 
the strengths of the official acids ? — Write formulae illustrative of all 
classes of orthophosphates. — Mention the chief tests for soluble and insolu- 
ble phosphates. — By what reactions may phosphates be distinguished 
from arsenates. 



Vanadium, V, 51.3, is a very rare element, and is here men- 
tioned only because of its exceedingly interesting relationship 
to nitrogen, phosphorus, arsenum, and antimony, it with them 
forming five closely-connected members of one family. Dis- 
covered, but not isolated, by Sefstrom, and its compounds 
investigated by Berzelius, it has only of late years been ob- 
tained in a free state and fully studied by Roscoe. 

N 2 5 , N 2 4 , N 2 3 , N 2 2 , N 2 0. v 2 5 , v 2 o 4 , v 2 o 3 , v 2 o 2 , VA 

Orthophosphates . . R / 3 P0 4 Orthovanadates . . R/ 3 V0 4 

Pyrophosphates . . B/ 4 P 2 7 Pyrovanadates . . R/ 4 V 2 7 

Metaphosphates . . R/P0 3 Metavanadates . . R / V0 3 

Isomorphous Minerals. 

Apatite 3(Ca 3 2P0 4 ),CaF 2 

Pyromorphite 3(Pb 3 2P0 4 ),PbCl 2 

Mimetesite 3(Pb 3 2As0 4 ),PbCl 2 

Vanadinite 3(Pb 3 2V0 4 ),PbCl 2 



BORATES. 333 

BORIC ACID AND OTHER BORATES. 

Formula of Boric Acid, H 3 B0 3 . Molecular weight, 62. 

The composition of artificial boric acid, sometimes termed ortho- 
boric acid, hydrogen borate, and boracic acid, is expressed by the 
formula H 3 B0 3 (Acidum Boricum, U. S. P.) ; out at a temperature 
of 212° F. this body loses the elements of water and yields metaboric 
acid, HB0 2 , which at higher temperature becomes boric anhydride 
(B 2 3 ). Metaboric acid exists in the jets of steam (fumerolles or 
suffioni) that issue from the earth in some districts of Tuscany, and 
collects in the water of the lagoni (lagoons or little lakes) formed at 
the orifices of the steam-channels. This acid liquid, evaporated by 
aid of the waste natural steam and neutralized by sodium carbonate, 
gives common borax, possibly a sodium and hydrogen metaborate, 
with water of crystallization (2NaB0 2 ,2HB0 2 ,9H 2 0), or possibly a 
sodium metaborate with boric anhydride (2NaBO 2 ,B 2 O 3 ,10II 2 O) ; or 
possibly a sodium pyroborate (Na 2 B 4 O\,10II 2 O), analogous to potas- 
sium pyrochromate (K 2 Cr 2 7 ) or pyrosulphuric acid (H 2 S 2 0\). It is 
sometimes termed sodium biborate. Its official name is Sodii Boras, 
Borate of Sodium or Sodium Borate. It occurs " in transparent 
colorless crystals, occasionally slightly effloresced, with a weak 
alkaline reaction ; insoluble in rectified spirit, soluble in water." 
Native borax, or tincal, and other borates are also found in Thibet, 
Nevada, Peru, Chili, and recently in California in the Clear Lake dis- 
trict. The introduction of the natural borax from California has 
reduced the price to about one-half its former amount. The Cali- 
fornian borax is represented as forming large portions of the crystal- 
line bed of a dried-up lake. Borax is also largely made by boiling 
native calcium borax with sodium carbonate. 

Fused borax readily dissolves metallic oxides, as will have been 
noticed already in testing for cobalt and manganese. Hence, besides 
its use in medicine, it is employed as a flux in refining and other 
metallurgic and ceramic operations. 

Quantivalence. — The boric radical is trivalent (B0 3 /// ) ; the meta- 
boric, univalent (BO/). 

The element boron, like carbon, occurs in the amorphous, graphi- 
toidal, and crystalline conditions. It is a trivalent element (B /// ), 
yielding definite salts, such as the chloride (BC1 3 ) and fluoride (BF 3 ). 
Its atomic weight is 11. 

Reactions. 
First Synthetical Reaction. — To a hot solution of a crystal 
of borax add a few drops of sulphuric acid and set aside ; on 
cooling crystalline scales of boric acid (H 3 B0 3 ) (Acidum Bori- 
cum, U. S. P.) are obtained. They may be purified by collect- 
ing on a filter, slightly washing, drying, digesting in hot alco- 
hol, filtering, and setting aside ; pure boric acid is deposited. 
The acid may also be recrystallized from water. 50 grains dis- 
solved in 1 ounce of rectified spirit constitute " Solution of 
Boric Acid," B. P. If 310 parts of boric acid be added to 
15* 



334 THE ACIDULOUS RADICALS. 

glycerin at 150° C, and after being kept at that temperature 
for some time diluted to 1000 parts, Glyceritum Boroglycerini, 
U. S. P., is obtained. Money of Borax, formed of 2 parts of 
borax to 16 of honey, is a very old antiseptic for the mouths 
of infants troubled by the growth called " thrush," the official 
British variety {Mel Boracis, B. P.) containing, in addition to 
the foregoing, 1 part of glycerin. 

Boric acid occurs in "colorless, pearly, lamellar crystals •, unctuous 
to the touch ; taste feebly sour and bitter and leaving a sweetish 
after-flavor in the mouth. Soluble in 25 parts of water, 5 of glycerin, 
16 of rectified spirit at 60° F. (15.5° C), and in 3 of boiling water. 
It changes the color of litmus to wine-red ; turmeric-paper, moistened 
with an aqueous solution slightly acidified with hydrochloric acid, 
becomes brownish-red on gently drying, and this color changes to a 
greenish if solution of potash be added. The alcoholic solution 
burns with a flame tinged with green. The crystals liquefy when 
warmed, and on careful ignition lose 43J per cent, of their weight, 
the product solidifying on cooling to a brittle glass-like mass (B. P.). 

Boric acid is a very weak compound. Indeed, the alkalinity of 
borax is as great as if it contained no acidulous material. The acid 
only slowly decomposes carbonates. 

Second Synthetical Reaction. — Mix together 1 part of boric 
acid, 4 parts of acid potassium tartrate, and 10 or 20 of water ; 
evaporate to a syrupy consistence, spread on plates, and set 
aside for dry scales to form. The resulting substance is, in 
water, far more readily soluble than either of its constituents, 
and is known as potassium boro-tartrate or soluble cream of tar- 
tar. The Prussian tartarus boraxatus differs from the foregoing 
French variety in containing 1 part of borax to 3 of acid potas- 
sium tartrate. 

Analytical Reactions (Tests). 

First Analytical Reaction. — Dip a piece of turmeric-paper 
(paper soaked in tincture of turmeric-tubers and dried) into a 
solution of boric acid ; it is colored brown red, as by alkalies. 

The usual way of applying this test is as follows : Add to a solu- 
tion of any borate a few drops of hydrochloric acid, immerse half 
of a slip of turmeric-paper in the liquid, then remove the hydro- 
chloric acid by drying the paper over a flame. Concentrated hydro- 
chloric acid and ferric chloride produce a somewhat similar effect. 

Second Analytical Reaction. — To a fragment of a borate or 
a metaborate (borax, for example) in a small dish or watch- 
glass add a drop of sulphuric acid, and then a little alcohol ; 
warm the mixture and set light to the spirit ; the resulting 
flame will be tinged of a greenish color at its edges by the 
volatilized metaboric acid or boric anhydride. 



BENZOATES. 335 

The liquid should be well stirred while burning. Salts of copper 
and some metallic chlorides produce a somewhat similar color. The 
flame-test may also be applied to a little of a mixture of the borate 
with strong sulphuric acid on a platinum wire. Glycerin may be 
used in place of sulphuric acid (lies), the reaction with borax being, 
according to Dunstan, the formation of glyceryl borate, C 3 H 5 B0 3 , 
water, and sodium metaborate, the glyceryl borate and water react- 
ing immediately to form boric acid and glycerin. 

Other Analytical Reactions. — In solutions of borax barium 
salts give a white precipitate (barium metaborate, Ba2B0 2 ), 
soluble in acids and alkaline salts. Silver nitrate also affords a 
white precipitate (silver metaborate, AgB0 2 ), soluble in nitric 
acid and in ammonia. Calcium chloride, if the solution is not 
too dilute, gives a white precipitate (calcium borate, CaB0 2 ). 



QUESTIONS AND EXEECISES. 

Illustrate the relation of vanadium to nitrogen by formulae of com- 
pounds of each element. — Describe the preparation of borax. — Give the 
formulae of boric acid, metaboric acid, and borax. — Mention the tests for 
borates or metaborates. 



The foregoing acids and other salts contain the only acididous 
radicals that are commonly met with in analysis or in ordinary 
medical or pharmaceutical operations. There are, however, many 
others which occasionally present themselves. The chief of these 
will now be shortly noticed ; they are arranged in alphabetical 
order to facilitate reference. 



SALTS OF RARER ACIDULOUS RADICALS. 

Anemonic Acid. — Pulsatilla, U. S. P., is the official name for the 
herbs of Anemone Pulsatilla and A. pratensis. These, together with 
several species of Ranunculus, on distillation with water yield a 
heavy, yellow, acrid oil, which in contact with water yields crystal- 
line poisonous anemonin (C 15 H 12 6 ) and amorphous anemonic acid 
(C ]5 H u 7 ). 

Benzoic Acid (HC 7 H 5 2 ) and other Benzoates. — Slowly 
heat a fragment of benzoin (gum benjamin) (Benzohmm, U. S. 
P.) in a test-tube ; benzoic acid (Acidum Benzoicum, U. S. P.), 
the hydrogen benzoate, rises in vapor and condenses in small, 
white, feathery plates and needles on the cool sides of the 
tube. If the benzoin is first mixed with twice its weight of 
sand or roughly powdered pumice-stone, and the heat very 
cautiously applied, the product will be less likely to be burnt 



336* SALTS OF RARER ACIDULOUS RADICALS. 

and a larger quantity will be yielded. By repeated sublima- 
tion 10 to 15 per cent, may be obtained. 

A more economical process is to boil the benzoin with one- 
fourth its weight of lime, filter, concentrate, decompose the 
solution of calcium benzoate by hydrochloric acid, collect the 
precipitated benzoic acid, press between paper, dry, and sublime 
in a tube or other vessel. 

2HC 7 II 5 2 + Ca2HO = Ca2C 7 H 5 2 + 2H 2 

Benzoic acid Calcium Calcium Water, 

(impure). hydrate. benzoate. 

Ca2C 7 H 5 2 + 2HC1 = CaCl 2 + 2IIC 7 H 5 2 

Calcium Hydrochloric Calcium Benzoic acid 

benzoate. acid. chloride. (pure). 

There is always associated with -the product a minute quantity 
of a mixture of volatile oils of agreeable odor, suggesting that of 
hay, and yielding, according to Jacobsen, methyl benzoate, guaiacol 
(methoxycatechoi), catechol, acetylguaiacol, benzyl benzoate, ben- 
zophenone, and benzoylguaiacol. 

Benzoic acid is also prepared on a large scale artificially from 
naphthalin, one of the crystalline by-products in the distillation of 
coal for gas. The naphthalin is oxidized by nitric acid to naphthalic 
or phthalic acid : 

C 10 H 8 + 40 2 - H 2 C 8 HA + H 2 C 2 4 

Naphthalin. Oxygen. Phthalic acid. Oxalic acid. 

The phthalic acid is neutralized by lime and the calcium phthalate 
heated with calcium hydrate in a covered vessel at a temperature 
of about 640° F. for several hours. Calcium benzoate and carbonate 
arc formed, and from the powder the benzoic acid is set free by 
by action of hydrochloric acid. 

2CaC 8 H 4 4 + Ca2HO = Ca2C 7 H 5 2 + 2CaC0 3 
Calcium Calcium Calcium Calcium 

phthalate. hydrate. benzoate. carbonate. 

The crystalline deposit formed when essential oil of almonds 
(benzoic aldehyde) is exposed to the air is benzoic acid. 

2C 6 II 5 COII + 2 = 2C 6 H 5 COOTI or 2HC V H 5 2 

Benzoic aldehyde. Oxygen. Benzoic acid. 

Pure sublimed benzoic acid is also obtained from hippuric acid 
(p. 340). Such acid, if not thoroughly purified, may have an 
urinoid odor. 

Jacobsen has prepared benzoic acid from benzotrichloride (tri- 
chloromethylbenzene, C 6 II 5 CC1 3 ), one of the trichlorotoluenes, by 
heating with glacial acetic acid and zinc chloride. This acid, if 
not very highly purified, may give a green color to flame when 
placed on platinum wire with a little copper oxide. In artificial 
benzoic acid the fragrant volatile oil characteristic of the acid from 
benzoin is of course absent. 

Official Benzoates. — To a little benzoic acid add a few drops 



BENZOATES. 337 

of solution of ammonia or of sodium carbonate ; it readily dis- 
solves, forming corresponding benzoates (Ammonii Beiizoas, 
U. S. P., Sod* Benzoas, U. S. P., NaC 7 H 5 2 ). 

HC 7 H 5 2 + NH 4 HO = NH 4 C 7 H 5 2 + H 2 

Benzoic acid. Ammonia. Ammonium benzoate. Water. 

On evaporation acid crystals or, ammonia being added, neu- 
tral crystals, of ammonium benzoate are deposited. 

Properties. — Benzoic acid is also soluble in other alkaline 
liquids, forming benzoates. It is slightly soluble in cold water, 
more so in hot, and readily soluble in rectified spirit. It melts 
at 248° F. and boils at 462°, volatilizing with only a slight 
residue. Heated with lime, it yields benzene. It dissolves in 
cold sulphuric acid without decomposition, is again deposited 
on dilution, and the traces of odoriferous and other substances 
present in the acid from benzoin only slightly color the fluid, 
even on gently warming. 

Tests for Benzoates. — To a portion of a solution of a ben- 
zoate add a drop or two of sulphuric or hydrochloric acid ; a 
white crystalline precipitate (benzoic acid) separates. To 
another portion, carefully made neutral, add a drop or two of 
neutral solution of ferric chloride ; ' a reddish precipitate (ferric 
benzoate) results. 

Cinnamic JLci'c?(C 8 H 7 COOH). — Benzoic acid is distinguished 
from an allied body, cinnamic acid, the hydrogen cinnamate 
(occurring in balsams of Peru, Tolu, and storax, and sometimes 
in benzoin), by not yielding benzaldehyde (C 6 H 5 COH) (oil of 
bitter almonds) when distilled with chromic acid ; that is, with 
a mixture of red potassium chromate and sulphuric acid, or 
when rubbed with half its weight of potassium permanganate. 

Old hard balsam of Tolu yields cinnamic acid on boiling 

with lime and water and precipitating by hydrochloric acid. 

Jacobsen makes it artificially by the prolonged reaction of 

glacial acetic acid and benzodichloride in the presence of zinc 
chloride. 

Carminic Acid (C u H u 8 ). — This is the coloring principle (about 
10 per cent.) of the dried female Coccus Cacti, or cochineal {Coccus, 
U. S. P.). The carmine of trade, when unadulterated {vide Phar- 
maceutical Journal,- 1859-60, p. 546), is carminic acid- united with 2 
or 3 per cent, of alumina and lime, or, occasionally, of tin oxide or 
albumen. It should be wholly soluble in solution of ammonia, giv- 
ing an apparently clear, rich purple liquid. Carmine with French 
chalk or starch constitutes face rouge or animal rouge. 

Merrick tests the relative value of several samples of cochineal or 
carmine by observing how much solution of potassium permanganate 



338 SALTS OF RARER ACIDULOUS RADICALS. 

is required to change the color of a decoction to faint pink. The 
silvery coating of cochineal is a wax, coccerin. 

Cetraric Acid is the bitter principle of Iceland "moss" (Cetra- 
ria, U. S. P.). In the lichen it is associated with much starch. 
Lichestearic also is present. 

Chrysophanic Acid (C 15 H ao 4 ). — This yellow acid is found in 
various species of rhubarb-root (Rheum, U. S. P.), and, under the 
name of parietinic acid, in various common yellow lichens. Kuble 
considers — DragendorfF also — that the chrysophanic acid of rhubarb 
is only produced when a glucoside, chrysophan, is acted on by a fer- 
ment in the presence of water. The formation of chrysophanic 
acid is probably, in most if not in all cases, preceded by the occur- 
rence of crysophan or an allied body. The author found it in 
"chrysarobin," a name given by Kemp to the pith, etc. of a legu- 
minous tree (Andira araroba), (Chrysarobinum, U. S. P.). Chrys- 
arobin is also known as Araroba powder, Bahia powder, Brazil 
powder, G-oa powder, and ringworm powder. The chrysarobin, as 
it occurs in the tree or when fresh, has been shown by Liebermann 
and Seidler to have the formula C 30 H 2t .O 7 ; this, by oxidation and 
elimination of water, yields the chrysophanic acid, more or less of 
which occurs with the chrysarobin according to the age of the 
chrysarobin, and to, perhaps, the presence or absence of a ferment. 
A solution of chrysarobin in alkali rapidly absorbs oxygen, the fluid 
yielding chrysophanic acid. Chrysophanic acid may be obtained in 
crystals of a golden-yellow color, hence the name (from xP v<y °Si 
chrusos, gold, and <paivo), phaino, I shine). Its synonyms are Rha- 
ponticin, Rheic Acid, Rhein, Rheumin, Rhubarbaric Acid, Rhubarb- 
arin, Rumicin. Chrysophanic acid, actual or potential, black, red- 
brown, and red resins (Aporetine, JPhceoretine, and Erythroretine), a 
bitter principle, and tannic acid are considered to be the conjoint 
source of the therapeutic properties of rhubarb. Chrysophanic acid 
may also be obtained from several species of Rumex or dock. " Ru- 
micin" is a preparation of yellow dock [Rumex, U. S. P.). Cascara 
Sagrada, or sacred bark [Rhamni Purshiani Cortex, B. P.), accord- 
ing to Limousin, contains chrysophanic acid, a glucoside (?), a fer- 
ment, and various resins being also said to be present. 

Emodin, C 15 H 10 O 5 , is apparently closely associated, chemically, 
with chrysophanic acid. It is obtained with chrysophanic acid in 
the preparation of the latter from rhubarb. It also occurs in black 
alder bark (Rhamni Frangulod Cortex, B. P.), according to Lieber- 
mann and Waldstein. It is said to be derived, together with glu- 
cose, from frangulin, C 21 H 20 O 9 , the glucoside of the dried bark. 

Cornic Acid, or Cornin. — This is, according to Geiger, the crys- 
talline bitter principle of the bark of Cornus fiorida or Dogwood. 
A crystalline resin is also present. 

Cyanic Acid (HCNO) and other Cyanates.— The redu- 
cing power of potassium cyanide (KCN) (or ferrocyanide, 



FORMATES. 339 

K 4 FeC 6 N 6 ) on metallic compounds is due to the avidity with 
which it absorbs oxygen and forms cyanate (KCNO). 

Process. — Fuse a few grains of potassium cyanide in a small 
porcelain crucible, and add powdered lead oxide ; a globule of 
metallic lead is at once set free, excess of the oxide converting 
the whole of the potassium cyanide into potassium cyanate. 

Urea. — Potassium cyanate (KCNO), or, better, lead cyanate 
(Pb2CNO), treated with ammonium sulphate, yields ammonium 
cyanate (NH 4 CNO) ; and solution of ammonium cyanate, when 
simply heated, changes to artificial urea (CH 4 N 2 0), the most im- 
portant constituent of urine, and the chief form in which the nitro- 
gen of food is eliminated from the animal system. The process will 
be more fully described subsequently in connection with Urea. 

Formic Acid (HCH0 2 ). — The red ant {Formica rufa) and several 
other insects when irritated eject a strongly acid, acrid liquid having 
a composition expressed by the above formula, and which has appro- 
priately received the name of formic acid ; it is also contained in the 
leaves of the stinging-nettle. (According to Church, the sting of 
the wasp is alkaline.) 

Process. — It may be artificially prepared by heating equal 
weights of oxalic acid and glycerin to a temperature of from 
212° to 220° F. for fifteen hours, and then distilling the mix- 
ture with a considerable volume of water. The formic acid 
slowly passes over, glycerin being regenerated. The dilute 
acid may be concentrated by neutralizing with lead carbonate, 
filtering, evaporating to a small bulk, collecting the deposited 
crystalline lead formate, drying, decomposing in a current of 
dry sulphuretted hydrogen at 212° F., and rectifying the 
resulting syrupy acid from dry lead formate. It should be 
fluid at 48° F. and boil at 212° F. The following are the chief 
reactions : 

C 3 H 5 3HO -f H 2 CA = C 3 H 5 HOC 2 4 + 2H 2 

Glycerin. Oxalic acid. Glyceryl hydrato-oxalate. Water. 

C 3 H 5 HOCA + 2H 2 = C 3 H 5 3HO + HCHO, + C0 2 

Glyceryl hydrate-- Water. Glycerin. Formic Carbonic 

oxalate. acid. anhydride. 

Formic Acid may be instructively though not economically pre- 
pared by the oxidatien of methylic alcohol (wood spirit), just as 
acetic acid and valerianic acid are obtained from ethylic alcohol 
and amylic alcohol respectively. 

CH 3 HO + 2 = HCH0 2 + H 2 

Methylic alcohol. Oxygen. Formic acid. Water. 

Tests. — Formic acid does not char when heated alone or with 
sulphuric acid, but splits up into carbonic oxide gas and water. It 



340 SALTS OF BARER ACIDULOUS RADICALS. 

is recognized by this property and by its reducing action on salts 
of gold, platinum, mercury, and silver. It is solid below 32° F. 

Gallic Acid. — See Tannic Acid. 

Hemidesmic Acid. — The supposed active principle of hemidesmus- 
root (Hemidesmi Radix, B. P.). 

Hippuric Acid (HC 9 H 8 N0 3 ) is a constituent of human urine 
(much increased on taking benzoic acid), but is prepared from the 
urine of the horse (hence the name, from lirTrog, hippos, a horse), or, 
better, from that of the cow. To such urine add a little milk of 
lime, boil for a few minutes, remove precipitated phosphates by 
nitration, drop in hydrochloric acid until the liquid, after well 
stirring, is exactly neutral to test-paper, concentrate to about one- 
eighth the original bulk, and add excess of strong hydrochloric 
acid ; impure hippuric acid is deposited. From a solution of the 
impure acid in hot water chlorine gas removes the color, and the 
liquid deposits crystals of pure hippuric acid on cooling. 

Tests. — To a solution of a hippurate add neutral solution of ferric 
chloride ; a brown precipitate (ferric hippurate) results. Salts of 
silver and mercury give white precipitates. Heat hippuric acid in 
a test-tube ; it chars, benzoic acid sublimes, and vapors of charac- 
teristic odor are evolved ; they contain, amongst other bodies, hydro- 
cyanic acid and a substance smelling somewhat like Tonka bean. 

The crystalline form of hippuric acid is characteristic ; it will 

be described in connection with the subject of Urine. 



QUESTIONS AND EXERCISES. 



Give the preparation, composition, properties, and tests of benzoic 
acid, employing equations or diagrams. — What is the nature of carmine? 
— Name the bitter principle of Iceland " moss." — Mention the coloring 
principle of rhubarb. — To what is rhubarb considered to owe its medi- 
cinal activity? — How is potassium cyanate prepared, how converted into 
an ammonium salt, and what are the relations of the latter to urea ? — 
Give the formula of cyanic acid, ammonium cyanate, and urea. — What 
is the chemical formula of formic acid ? — Describe the artificial produc- 
tion of formic acid. — Describe the relation of formic acid to wood spirit. 
— State the sources, characters, and tests of hippuric acid. 



Hydroferrocyanic Acid (H 4 Fe // Cy 6 or H 4 Fcy //// ) and other 
Ferrocyanides. — The ferrocyanide of most interest is that of potas- 
sium, the old "yellow prussiate of potash" (Potassii Ferrocyani- 
dum, U. S. P.) (K 4 FeC 6 N 6 ,3H 2 0), the formation of which was alluded 
to in connection with hydrocyanic acid (see p. 280). It cannot be 
regarded as simply a double salt of potassium cyanide Avith ferrous 
cyanide (FeCy 2 ,4KCy), its chemical properties being entirely differ- 
ent from either of those substances : moreover, unlike potassium 
cyanide, it is not poisonous. Most of the reactions point to the 



FERRICYANIDES. 341 

conclusion that its iron and cyanogen are intimately united to form 
a definite quadrivalent radical appropriately termed ferrocyanogen 
(FeC 6 N 6 or Fey). 1 part of potassium ferrocyanide in 10 of water 
forms the official " Potassium Ferrocyanide Test-solution," U. S. P. 

Tests. — Many of the ferrocyanides are insoluble, and are 
therefore precipitated when solution of potassium ferrocyanide 
is added to the various salts. Those of iron and copper, being 
of characteristic color, are adopted as tests of the presence of 
the metals or of the ferrocyanogen, as the case may be. To 
solution of potassium ferrocyanide add a ferric salt ; a dark- 
blue precipitate (iron ferrocyanide, Fe 4 Fcy 3 , prussian blue) 
falls. To another portion add solution of a copper salt ; a red- 
dish-brown precipitate (copper ferrocyanide, Cu 2 Fcy) results. 

Note. — The ferrocyanogen in potassium ferrocyanide is broken up 
when the salt is heated with sulphuric acid, carbonic oxide being 
evolved if the acid is strong (that is, ordinary oil of vitriol — H 2 S0 4 
with 2 or 3 per cent, of water), and hydrocyanic acid if weak: 

K 4 FeC 6 N 6 ,3H 2 + 3H 2 + 6H 2 S0 4 = 2K 2 S0 4 + FeS0 4 

+ 3(NH 4 ) 2 S0 4 + 6CO. 

2K 4 FeCv 6 + 6H 2 S0 4 + xll 2 = FeK 2 FeCy 6 + 6KHS0 4 + 6HCy 

4- *H 2 0. 

Hydrocyanic Acid has already been described. {Vide p. 279.) 

Carbonic Oxide (CO). — Heat two or three fragments of potas- 
sium ferrocyanide with eight or ten times their weight of sulphuric 
acid, and as soon as the gas begins to be evolved remove the test- 
tube from the flame, for the action, when once set up, proceeds 
somewhat tumultuously. Ignite the carbonic oxide at the mouth 
of the tube ; it burns with a pale-blue flame, the product of combus- 
tion being carbonic acid gas (C0 2 ). 

Carbonic oxide is a direct poison. It is generated whenever coke, 
charcoal, or coal burns with an insufficient supply of air. Hence 
the danger of open fires in the more or less closed apartments of 
ordinary dwellings. 

Carbonic oxide may also be obtained from oxalic acid. {Vide 
p. 371.) 

Hydroferricyanic Acid (H 6 Fe"' 2 Cy 12 or H 6 Fdcy vl ) and 
other Ferricyanides. — Pass chlorine gas slowly through 
solution of potassium ferrocyanide until the liquid, after fre- 
quent shaking, ceases to give a blue precipitate, when a minute 
portion is taken out on the end of a glass rod and brought into 
contact with a drop of dilute solution of a ferric salt; it now 
contains potassium ferricyanide (B. P.) (R^Fe^Cy^ or 
K 6 Fdcy vl ), red prussiate of potash, as it is termed from the color 
of its crystals. Excess of chlorine must be carefully avoided, 
as cyanogen chloride and other compounds are then formed. 
(Such a result does not ensue if bromide be used instead of 



342 SALTS OF RARER ACIDULOUS RADICALS. 

chlorine, but the process is less economical. Other processes 
are known.) 

2K' 4 Fe"Cy' 6 + C1' 2 = 2K'CI' + K' 6 Fe 2 '"Cy' 12 . 

Note. — The removal of two atoms of potassium from the ferro- 
cyanide molecules is the only change of composition that occurs 5 
but the ferrocyanogen is altered in quality, its iron passing from 
the ferrous to the ferric condition, from bivalent to trivalent 
activity — altered to a condition in which it no longer precipitates 
ferric salts, but gives a dark-blue precipitate with ferrous salts. 

The radical is distinguished as ferricyanogen. 

Test. — To some of the solution add solution of ferrous sulphate ; a 
dark-blue precipitate falls. This precipitate is ferric ferricyanide 
(Turnbull's blue), Fe // 3 Fe /// 2 Cy / 12 or Fe" 3 Fdcy VI . 

K 6 Fdcy + 3FeS0 4 = Fe 3 Fdcy + 3K 2 S0 4 . 

It will be noticed that the change in the condition of the iron 
keeps up the balance of the atomic values of the various parts of 
the radicals or of the salts ; the quantivalential equilibrium is main- 
tained. 

A solution of 1 part of potassium ferricyanide in about 10 parts 
of water constitutes the " Potassium Ferricyanide Test-solution," 
U. S. P. 

Hydrofluoric Acid (HF) and other Fluorides. — Molec- 
ular weight of HF, 20. The chief use of hydrofluoric acid 
is in etching on glass. The operation, performed on the small 
scale, also constitutes the best test for fluorine, the elementary 
radical of all fluorides. 

Process and Test. — Warm any odd piece of window-glass, 
having an inch or two of surface, until a piece of beeswax 
rubbed on one side yields a thin oily film. When cool, make 
a cross, letter, or other mark on the glass by pressing a pointed 
piece of wood, a penknife, or file through the wax. Place a 
few grains of powdered fluor-spar, the commonest natural fluor- 
ide, in a porcelain crucible (or a lead cup), add a drop or two 
of sulphuric acid, cover the crucible with the prepared glass, 
waxed side downward, and gently warm the bottom of the 
crucible in a fume-chamber or in the open air in such a way as 
not to melt the wax. After a few minutes remove the glass, 
wash the waxed side by pouring water over it, scrape off" most 
of the wax, then warm the glass and wipe off the remainder ; 
the marks made through the wax will be found to be perma- 
nently etched on the glass ; the acid has eaten into or etched 
(from the German atzen, to corrode) the glass. 

Calcium fluoride and sulphuric acid yield hydrofluoric acid, thus : 
CaF 2 4- H 2 S0 4 = CaS0 4 -f 2HF. The hydrofluoric acid gas and the 
silica of the glass then yield gaseous silicon fluoride (SiFJ, which 



HYPOPHOSPHITES. 343 

escapes, and water, thus : 4HF + Si0 2 = 2H 2 -+- SiF 4 . 

being removed from the glass, leaves furrows or etched portions. 

Note. — In the experiment just described the liberated hydro- 
fluoric acid also attacks the siliceous glazing of the porcelain cruci- 
ble ; so that in important cases, where search is made for very 
small quantities of fluorine, vessels of platinum or lead must be 
employed. 

Uses. — The aqueous solution of hydrofluoric acid, used by etchers, 
and commonly termed simply hydrofluoric acid or "fluoric" acid, is 
prepared in leaden stills and receivers and kept in leaden or gutta- 
percha bottles. Except these materials, as well as platinum and 
fluor-spar, hydrofluoric acid rapidly attacks any substance of which 
bottles and basins are usually made. It quickly cauterizes the skin, 
producing a painful, slow-healing sore. A mixture of hydrofluoric 
acid and ammonium fluoride, known as "white acid," is also used 
for etching glass. 

Quantivalence. — The atom of fluorine, like that of chlorine, 
bromine, or iodine, is univalent (F / ). The great analogy existing 
between these radicals extends to their compounds. 

Fluorine has been isolated by electrolyzing hydrofluoric acid 
(Moissan). It is a gas having a light greenish-yellow color and a 
penetrating and irritating odor, somewhat recalling that of strong 
hypochlorous acid. It combines with great avidity with all elements 
except oxygen. 

Hypophosphorous Acid (H 3 P0 2 or HPH 2 2 ) and other 
Hypophosphites. — Boil together in a fume-chamber, two or 
three grains of phosphorus, three or four grains of slaked lime, 
and about a quarter of an ounce of water, until phosphoretted 
hydrogen, a spontaneously inflammable, badly-smelling gas, 
ceases to be evolved. The lime must not be in great excess, or 
the hypophosphite will be converted into phosphate as fast as 
formed. The mixture, filtered and excess of lime removed by 
carbonic acid gas, yields solution of calcium hypophosphite 
(Ca2PH 2 2 ) (Calcii Hypophosphis, IT. S. P.). The salt may be 
obtained in crystals by evaporation and slow cooling. 

2P 4 + 6H 2 + 3CaH 2 2 = 3(Ca2PH 2 2 ) + 2PH 3 . 

Phosphoretted Hydrogen (PH 3 ). — The above reaction is also that 
by which phosphoretted hydrogen, the third hydride of phosphorus, 
may be prepared. If the gas is to be collected, the phosphorus and 
water may first be boiled in a flask until a jet of spontaneously 
inflammable phosphorus vapor escapes, with steam, from the end 
of the attached delivery-tube. Strong hot solution of caustic potash 
or soda is next very gradually poured into the flask through a 
funnel tube previously fitted into the cork, the liquid being kept 
boiling. Phosphoretted hydrogen is then evolved, and, if the 
delivery-tube dip under water, may be collected, or allowed to slowly 
pass up through the water, bubble by bubble, so as to burst 
spontaneously into flame and form the peculiar vortex rings of 



344 SALTS OF RARER ACIDULOUS RADICALS. 

smoke (phosphoric anhydride) characteristic of the experiment. The 
spontaneous inflammability is due to the presence of a lower 
hydride, P 2 H 4 . 

Other hypophosphites (Mg2PH 2 2 ,6H 2 ; Fe2PH 2 2 ,6H 2 ; etc.) 
may thus be obtained from other hydrates or by double decomposi- 
tions of the calcium salt and carbonates. 

The potassium hypophosphite (Potassii Hypophosphis, U. S. P.) 
(KPH 2 2 ) may be obtained in the same way from its hydrate, and 
many other hypophosphites (Mg2PH 2 2 ,6H 2 0, Fe2PH 2 2 ,6H 2 0, etc.) 
similarly from other hydrates, or by double decomposition of the 
calcium salt and carbonates. 

Sodium Hijpophosphite (NaPH 2 2 ,H 2 0) (Sodii Hypophosphis, 
U. S. P.), the old soda hypophosphite, is made by decomposing 
solution of calcium hypophosphite by sodium carbonate, filtering, 
and evaporating to dryness. It is a white, granular, or lamellar 
deliquescent substance : Ca2PH 2 2 + Na 2 C0 3 = 2NaPH 2 2 + CaC0 3 . 
When heated, the water is first evolved, then hydrogen and 
spontaneously inflammable phosphoretted hydrogen, and a mixture 
of sodium pyrophosphate and metaphosphate remains (Rammels- 
burg) : 5NaPH 2 2 = Na 4 P 2 7 + NaP0 3 + 2PH 3 + 2H 2 . 

Hypophosphorous Acid, the hydrogen hypophosphite, may be pre- 
pared by decomposing the calcium salt by oxalic acid, or, better, the 
pure barium salt by sulphuric acid, filtering and evaporating ; qui- 
nine hypophosphite by dissolving the alkaloid in hypophosphorous 
acid, or by decomposing quinine sulphate by barium hypophosphite. 
The latter is obtained on boiling excess of pure barium hydrate with 
ammonium hypophosphite until all ammonia is evolved. The am- 
monium salt is formed on bringing calcium hypophosphite and 
ammonium oxalate together in presence of a little ammonia. 

Diluted Hypophosphorous Acid is official (Acidum Hyphosphorosum 
Dilutum, U. S. P.). It is a colorless, inodorous, sour liquid, contain- 
ing about 10 per cent, of the real acid. 

Hypophosphite of Iron (Fe 2 6PH 2 2 ) (Ferri Hypophosphis, U. S. P., 
N. P.) or Ferric Hypophosphite, may be obtained by dissolving ferric 
hydrate in cold aqueous hypophosphorous acid and evaporating the 
solution. 

The hypophosphites are often used in medicine in the form of 
syrups (Syrupus Hypophosphitum, U. S. P., and Syr. Hypophos- 
phitum cum Ferro, U. S. P.). The term hypophosphite is in allusion 
to the smaller amount {vtto, hupo, under or deficiency) of oxygen in 
these compounds (R/ 3 P0 2 ) than in the phosphites (R 3 P0 3 ), a class of 
salts having again less oxygen in their molecules than exists in 
those of the phosphates (R 3 P0 4 ). The prefix hypo has similar sig- 
nificance in such words as hyposulphite and hypochlorite. 

Tests. — To a portion of the above solution of calcium hypo- 
phosphite add solution of barium chloride, calcium chloride, or 
lead acetate ; in neither case is a precipitate obtained, whereas 
soluble phosphates and phosphites yield white precipitates (of 
barium calcium or lead phosphate or phosphite). To other 



HYPOPHOSPHITES. 345 

portions add solutions of silver nitrate and mercuric chloride ; 
the respective metals (HgO first, then Hg) are precipitated as 
by phosphites. To another small portion add zinc and dilute 
sulphuric acid ; hydrogen and phosphoretted hydrogen are 
evolved as from phosphites. To another portion add sufficient 
oxalic acid to remove the calcium ; filter ; to the solution of 
hypophosphorous acid add solution of copper sulphate and 
slowly warm the mixture ; a solid brown precipitate results 
(cuprous hydride, Cu 2 H 2 ) : increase the heat to the boiling- 
point ; a gas (hydrogen) is evolved and metallic copper is set 
free. Add the ordinary nitric solution of a molybdate or tung- 
state to a hypophosphite solution, and then a very little sul- 
phurous acid ; a blue precipitate results, or in very dilute 
solutions a blue color, deepened on shaking or gently warming. 
Heat a small quantity of a solid hypophosphite on the end of 
a spatula in a flame, and note the resulting phosphorescent 
light and smell ; for it splits up into pyrophosphate, a little 
metaphosphate, hydrogen, phosphoretted hydrogen, and water, 
the official calcium hypophosphite yielding about 80 per cent, 
of residue. The free acid undergoes similar but more complete 
decomposition. 

7(Ca2PH 2 2 ) = 3Ca 2 P 2 7 + Ca2P0 3 + 6PH 3 + H 2 + 4H 2 . 

5 grains of calcium hypophosphite, if of good quality, will 
almost decolorize a solution of 12 grains of potassium perman- 
ganate on boiling the mixture for about ten minutes. 5 grains 
of sodium hypophosphite should almost decolorize 11 J grains 
of permanganate under similar conditions. 

The same effect follows the addition of the permanganate to 
an acid solution of a phosphite, but not to that of an ortho-, 
meta-, or pyro-phosphate. 

Hyposulphurous Acid (H 2 S 2 3 ) and other Hyposul- 
phites. — The only hyposulphite of much interest in pharmacy 
is the sodium salt {Hyposulphite of Sodium, U.S. P., the old 
hyposulphite of soda) (Na 2 S 2 3 ,5H 2 0). Hyposulphites are 
now more usually termed Thiosulphates (e. g. H«S0 3 S ; Na 2 S0 3 S), 
being regarded as sulphates {e.g. Na 2 S0 4 ) in whose molecules 
one atom of oxygen is displaced by one of sulphur (delov, 
theion, sulphur.) 

Process. — Heat together gently or set aside in a warm place 
a mixture of solution of sodium sulphite (Na 2 S0 3 ) and a little 
powdered sulphur ; combination slowly takes place and sodium 
hyposulphite is formed. The solution, filtered from excess of 
sulphur, readily yields crystals. (The solution of sodium 



346 



SALTS OF BARER ACIDULOUS RADICALS. 



sulphite may be made by saturating solution of soda with sul- 
phurous acid gas.) 

Use of Sodium Hyposulphite in Quantitative Analysis. — In 
the British Pharmacopoeia sodium hyposulphite is given as a 
reagent for the quantitative estimation of free iodine in volu- 
metric analysis. To a few drops of iodine-water add cold 
mucilage of starch ; a deep-blue color (starch iodide) is pro- 
duced. To the product add solution of sodium hyposulphite 
until the blue color just disappears. This absorption of iodine 
is sufficiently definite and delicate to admit of application for 
quantitative purposes. It depends on the combination of the 
iodine with half of the sodium in two molecules of the hypo- 
sulphite, the hyposulphurous radicals of the two molecules 
apparently coalescing to form a new radical, the tetrathionic 
(from rirpas, tetras, four, and deTov, theion, sulphur), sodium 
tetrathionate (Na 2 S 4 6 ) and sodium iodide being formed. 

Sulphur Oxyacids. — It will be as well here to give the for- 
mulae of other oxyacids of sulphur, forming with the four 
already mentioned a series that is as useful as the series of 
compounds of nitrogen and oxygen in illustrating the sound- 
ness of Dalton's atomic theory. The first-named (see table 
below) (H 2 S0 2 ) is more usually termed hyposulphurous acid, 
and the fourth (H 2 S 2 3 ) thiosulphuric acid. Moreover, there 
appears to be an acid (H 2 S 2 4 ) between those having the for- 
mulae H 2 S 2 3 and H 2 S 2 6 , which Bernthsen says is really 
Schiitzenberger's hydrosulphurous acid, but which the latter 
chemist says is probably a distinct acid : 



Hydrosulphurous acid H 2 S0 2 
Sulphurous acid . . . H 2 S0 3 
Sulphuric acid .... H 2 S0 4 
Hyposulphurous, or 

Thiosulphuric acid H 2 S 2 3 



Dithionic acid . . 
Trithionic acid . 
Tetrathionic acid 
Pentathionic acid 



H 2 S 2 4 
H 2 S 2 6 
H 2 S 3 6 
H 2 S 4 6 
H 2 S 5 6 



Use of u Hypo" in Photography. — The sodium hyposulphite 
is ' largely used in photography to dissolve silver chloride, 
bromide, or iodide off plates which have been exposed in the 
camera. Prepare a little silver chloride by adding a chloride 
(sodium chloride) to a few drops of solution of silver nitrate. 
Collect the precipitated chloride on a filter, wash, and add a 
few drops of solution of sodium hyposulphite ; the silver salt 
is dissolved, solution of sodium and silver hyposulphite 
being formed. The solution of this double hyposulphite has 
a remarkably sweet taste, sweeter than syrup if the solu- 
tion is strong. The double sodium and gold hyposulphite 



LACTATES. 347 

has been employed for giving a pleasant tint to photographic 
prints. 

Test. — To solution of a hyposulphite add a few drops of 
dilute sulphuric or other acid and smell the mixture cautiously ; 
hyposulphurous acid is set free, but. at once begins to decom- 
pose into sulphurous acid, recognized by its odor, and free 
sulphur (2H 2 S 2 3 = 2H 2 S0 3 + S 2 ). This reaction constitutes 
the best test for hyposulphites. Another test of a soluble 
simple hyposulphite is its power of dissolving silver chloride 
with production of a more or less sweet solution. 



QUESTIONS AND EXEECISES. 

Give the formula of potassium ferrocyanide. — What is the supposed 
constitution of potassium ferrocyanide ? — Enumerate the tests for ferro- 
cyanogen. — What are the respective reactions of potassium ferrocyanide 
with strong and weak sulphuric acid ? — Mention and explain a common 
source of carbonic oxide in households. What is the product of its com- 
bustion? — Write equations or diagrams illustrative of the changes 
effected in potassium ferrocyanide during its conversion into ferricyanide. 
By what reactions may the presence of a ferricyanide in a solution be 
demonstrated ? — State the difference between prussiau blue and Turn- 
bull's blue, — Describe the source, mode of preparation, chief use of, and 
test for, hydrofluoric acid. — Illustrate by a diagram the preparation of 
sodium hyposulphite. — Mention the characteristic reactions of sodium 
hyposulphite. — Give the names and formulae of eight acids each contain- 
ing hydrogen, sulphur, and oxygen. 



Lactic Acid (HC 3 H 5 3 ) and other Lactates. — Lactic acid 
occurs naturally in willow-bark (Dott). When milk turns sour, 
its sugar has become converted into an acid appropriately 
termed lactic (Jac, lactis). Other saccharine and amylaceous 
substances also by fermentation yield lactic acid. The hydro- 
gen lactate (lactic acid) is official (Acidum Lacticum, U. S. P.). 

Process. — Calcium lactate and lactic acid may be prepared as 
follows : Mix together 8 parts of sugar, 1 of common cheese, 
3 of chalk, and 50 of water, and set aside in a warm place 
(about 80° F.) for two or three weeks ; a mass of small crys- 
tals of calcium lactate results. Remove these, recrystallize 
from hot water, decompose by sulphuric acid, avoiding excess, 
digest in alcohol, filter off the calcium sulphate, evaporate the 
clear solution to a syrup : this residue is ordinary lactic acid, 
Acidum Lacticum II. S. P., sp. gr. 1.213; it contains 75 per 
cent, of real acid. 3 fluid parts of this acid diluted with water 
to 20 fluid parts forms the Acidum Lacticum Dilutum, B. P. ; 
sp. gr. 1.040. 

Strontium Lactate, Sr(C 3 H 5 03) 2 ,3H 2 (Strontii Lactas, IT. S. 
P.) is a permanent white crystalline powder, soluble in water 



348 SALTS OF RARER ACIDULOUS RADICALS. 

and in alcohol. It may be prepared by dissolving the car- 
bonate in lactic acid. 

2(HC 3 H 5 3 ) + SrC0 3 = Sr(C 3 H 5 3 ) 2 + H 2 + C0 2 

Filter, concentrate, and allow to crystallize. 

Ferrous Lactate (Ferri Lactas, U. S. P., Fe2C 3 H 5 3 ,3H 2 0) 
may be made by digesting iron filings in warm diluted lactic 
acid (1 acid to 16 water) till effervescence of hydrogen ceases, 
filtering, and setting aside to cool and crystallize. The crystals 
are collected, washed with alcohol, and 'dried. This ferrous 
lactate occurs in greenish-white crystalline crusts or grains, of 
a mild, sweetish, ferruginous taste, soluble in 48 parts of cold 
and 12 of boiling water, but insoluble in alcohol. Exposed to 
heat, it froths up, gives out thick white acid fumes, and 
becomes black, sesquioxide of iron being left. If it be boiled 
for fifteen minutes with nitric acid of the specific gravity 1.20, 
a white granular deposit of mucic acid will occur on the cool- 
ing of the liquid. 

Test. — No single reaction of lactic acid is sufficiently dis- 
tinctive to form a test. The crystalline form of the calcium 
lactate, as seen by the microscope, is characteristic. The pro- 
duction of this salt and the isolation of the syrupy acid itself 
are the only means, short of quantitative analysis, on which 
reliance can be placed. Lactic acid is soluble in water, alcohol, 
and ether, but almost insoluble in chloroform. It is only 
slightly colored by cold sulphuric acid. Warmed with potassium 
permanganate, it gives the odor of aldehyde. 

A variety of lactic acid has been obtained from the juice of 
flesh ; it is termed sarcolactic acid (from aap^. <rapxds, sarx, sar- 
cos, flesh) Unlike lactic acid, it is precipitated by solution of 
copper sulphate. 

Malic Acid (C 4 H 6 5 ) and other Malates (from malum, an apple). 
— The juice of unripe apples, gooseberries, currants, rhubarb- 
stalks, strawberries, grapes, etc. contains malic acid, hydrogen 
malate and potassium malate. When isolated it occurs in deliques- 
cent prismatic crystals. 

Tests. — Calcium malate (CaC 4 H 4 5 ) is soluble in water ; 
hence the aqueous solution of malic acid or other malate is not 
precipitated by lime-water or calcium chloride ; but on adding 
spirit of wine a white precipitate falls, owing to the insolubility 
of the calcium malate in alcohol. Malates are precipitated by 
lead salts ; on warming the precipitate (lead malate) with acetic 
acid, it dissolves, separating out in acicular crystals on cooling. 
If the mixture be heated without acid, the precipitate aggluti- 



MECONATES. MET A PHOSPHATES. 349 

nates and fuses. Hot strong sulphuric acid chars malic acid 
far less readily than it does nearly all other organic acids. 

Asparagin (C 4 H 8 N 2 3 ,H 2 0). — This proximate principle of plants 
occurs in many vegetable juices, and doubtless plays a very import- 
ant part in their nutrition. It is deposited in crystals when the 
fresh juices of asparagus, marsh-mallow, etc. are rapidly evapor- 
ated. It is noticed here because malic acid is readily obtained 
from it by oxidation, nitrogen being eliminated, and because its 
exact natural position among chemical substances is not yet well 
made out. The atoms of its molecule are those of ammonium 
aspartate (NH 4 C 4 H 6 N0 4 ), into which it is converted when its solu- 
tion is long boiled. Decomposed by aid of ferments, asparagin, 
absorbing hydrogen, yields ammonium succinate (NH 4 ) 2 C 4 H 4 4 . 

Meconic Acid (H 2 C 7 H 2 7 ,3H 2 0). — Opium contains meconic 
acid (from fj.rjxc»v, mekon 1 a poppy) partially combined with 
morphine. To concentrated infusion of opium, nearly neutral- 
ized with ammonia, add solution of calcium chloride ; calcium 
meconate is precipitated. Wash the precipitate, place it in a 
small quantity of hot water ; add a little hydrochloric acid ; 
the clear liquid (filtered if necessary) deposits scales of me- 
conic acid on cooling (Acidum Meconicum, B. P.). 

Tests. — To solution of meconic acid or other meconate or to 
infusion of opium add a neutral solution of ferric chloride ; a 
red solution (of ferric meconate) is produced. To a portion of 
the mixture add solution of corrosive sublimate; the color is 
not destroyed : to another portion add hydrochloric acid ; the 
color is discharged. (These reagents act on iron sulphocyanate, 
which is of similar tint, in exactly the opposite manner.) To 
another portion add a drop of a diluted acid and boil ; the color 
is not discharged. (A solution of ferric acetate, which is of 
similar color, is decomposed in boiling, giving a colorless fluid 
and a red precipitate — ferric oxyacetate.) 

The normal potassium, sodium, and ammonium meconates are 
soluble in water, the acid meconates very slightly soluble ; barium, 
calcium, lead, copper, and silver meconates are insoluble in water, but 
soluble in acetic acid. 

Metaphosphoric Acid (HP0 3 ) and other Metaphos- 
phates. — Prepare phosphoric anhydride (P 2 5 ) by burning a 
small piece of phosphorus in a porcelain crucible placed on a 
plate and covered by an inverted test-glass, tumbler, half-pint 
measure-glass, or some such vessel. After waiting a few min- 
utes for the phosphoric anhydride to fall, pour a little water on 
the plate and filter the liquid ; the product is solution of meta- 
phosphoric acid (from /j^rd, meta, a preposition denoting change) 
or hydrogen metaphosphate, P 2 5 -f H 2 = 2HP0 3 . 
16 



350 SALTS OF KAKER ACIDULOUS RADICALS. 

Tests. — To solution of metaphosphoric acid add silver amnio- 
nio-nitrate, or to a neutral metaphosphate add solution of silver 
nitrate ; a white precipitate (AgP0 3 ) is obtained. This reac- 
tion sufficiently distinguishes metaphosphates from the ordinary 
phosphates or orthophosphates (from opdo?, orthos, straight), 
as the common phosphates may, for distinction, be termed 
(which give, it will be remembered, a yellow precipitate with 
silver nitrate). Another variety of phosphates shortly to be 
considered, the pyrophosphates, also give a white precipitate 
with silver nitrate. To the solution of metaphosphoric acid 
obtained as above, or by the action of acetic acid on a meta- 
phosphate, add an aqueous solution of white of egg ; coagula- 
tion of the albumen ensues. Neither orthophosphoric nor pyro- 
phosphoric acid coagulates albumen. Boil the aqueous solu- 
tion of metaphosphoric acid for some time ; on testing the 
solution the acid will be found to have been converted into 
orthophosphoric acid : 

HP0 3 + H 2 = H 3 P0 4 (orthophosphoric acid). 

The ordinary medicinal phosphoric acid is made from phos- 
phorus and nitric acid, the liquid being evaporated to a syrupy 
consistence to remove the last traces of nitric acid. It may 
contain pyrophosphoric and metaphosphoric acids if the heat 
employed be high enough to remove the elements of water : 

2H 3 P0 4 — H 2 = H 4 P 2 7 (pyrophosphoric acid). 
H3PO4 — H 2 = HP0 3 (metaphosphoric acid). 

On redilution the metaphosphoric acid only slowly reabsorbs 
water. - If, therefore, on testing, metaphosphoric acid be found 
to be present, the solution should be boiled until conversion to 
orthophosphoric acid has occurred. 

Nitrous Acid (HN0 2 ) and other Nitrites. — Strongly 
heat a fragment of potassium or sodium nitrate on a piece of 
platinum-foil ; oxygen is evolved and potassium or sodium 
nitrite remains. 

Test. — Dissolve the residue in water, add a few drops of 
dilute sulphuric acid, then a little weak solution of potassium 
iodide, and, lastly, some starch mucilage ; the deep-blue " starch 
iodide" is produced: 2HI f 2HN0 2 = 2H 2 + 2NO f I 2 . 
Repeat this experiment, using potassium nitrate instead of 
nitrite ; no blue color is produced. 

Test for Nitrites in Water. — This liberation of iodine by nitrites, 
and not by nitrates, is a reaction of considerable value in searching 
for nitrites in ordinary drinking waters, the occurrence of such 



NITRITES. 351 

salts, except in very deep-seated springs, being held to indicate the 
presence of nitrogenous organic matter in a state of oxidation or 
decay. The sulphuric acid used in the operation must be pure and 
the potassium iodide free from iodate. If much organic matter is 
present, however, the nitric acid liberated by the sulphuric may be 
reduced to nitrous acid. It is perhaps best, therefore, to add acetic 
acid, and (Fresenius) distil over 10 or 20 per cent, of the water and 
apply the test to this distillate. Very dilute solutions of nitrous 
acid may thus be distilled without the slightest decomposition. 

Commercial Nitrous Acid. — The liquid commonly termed in 
pharmacy "nitrous acid" is simply nitric acid impure from the 
presence of nitrous acid. 

Other nitrites used in medicine are nitrites of organic basylous 
radicals : ethyl nitrite (C 2 H 5 N0 2 ), or nitrous ether, is the most 
important constituent of Spii'itus ^Etheris Nitrosi, U. S. P. ( Vide 
Index.) Amyl nitrite (C 5 H n N0 2 ) is also official {Amyl Nitris, 
U. S. P.). Ammonium nitrite, on being heated, yields pure nitrogen 
gas: 

NH 4 N0 2 = 2H 2 + N 2 . 

Sodium Nitrite, NaN0 2 (Sodii Nitris, U. S. P.). It yields ruddy 
nitrous fumes on the addition of sulphuric acid, and gives the usual 
deep-brown color with iron sulphate (p. 289). It is in the form of 
white fused masses or colorless hexagonal crystals, slightly deli- 
quescent, and gradually oxidizes in the air to nitrate ; very soluble 
in water, but only slightly so in alcohol. The official salt should 
conform to the following tests : It should readily dissolve in 20 parts 
of water, forming a colorless solution, and leaving no insoluble resi- 
due (absence of insoluble mucilage impurities). If 1 one drop of 
hydrochloric acid and a few drops of starch be added to 5 cc. of the 
aqueous solution, no blue coloration should appear (absence of 
iodide). 5 cc. of the aqueous solution, mixed with an equal volume 
of hydrogen sulphide, should produce no coloration or precipitate 
(absence of lead, arsenic, copper, etc.). 0.15 grm. of sodium nitrite 
dissolved in 5 cc. of water and introduced into a nitrometer, followed 
by a solution of 1 grm. "of potassium iodide in 6 cc. of water and 15 
cc. of normal sulphuric acid, should liberate nitrogen dioxide gas, 
which should measure not less than 50 cc. at 15° C. (59° F.) or 
51.7 cc. at 25° C. (77° F.), corresponding to not less than 97.6 per 
cent, of the pure salt. 

Ophelic Acid (C 13 H 20 O 10 ). — This is one of the principles to which 
the herb Ophelia chirata, or Chiretta (Chirata, B. P.), owes its bit- 
terness. It is an amorphous yellow body. Another is Chiratin 
(C 26 H 48 15 ), decomposable by hydrochloric acid into Chiratogenin 
(C 13 H 24 3 ) and ophelic acid (Hohn). 

Phosphorous Acid (H 3 P0 3 , or P(OH) 3 , or H 2 PH0 3 ).— The three 
acids of phosphorus — namely, phosphoric acid (H 3 P0 4 ), phospho- 
rous acid (H 2 PH0 3 ), and hypophosphorous acid (HPH 2 2 ) — differ 
from each other in the proportion of oxygen, the molecules contain- 
ing four, three, and two atoms respectively. In constitution they 



352 



SALTS OF RARER ACIDULOUS RADICALS. 



differ by the hypothetical phosphoric radical or grouping being 
trivalent, the phosphorous radical bivalent, and the hypophospho- 
rous radical univalent. These three acids and corresponding salts 
must not be confounded with pyrophosphoric and metaphosphoric 
acids and salts : the former are acids of phosphorus ; the latter 
varieties of phosphoric acid : the former differ in proportion of 
oxygen, the latter by the elements of water : 



Acids of Phosphorus. 



Varieties of Phosphoric Acid. 



H 3 P0 4 , phosphoric acid. H 3 P0 4 , (ortho)phosphoric acid. 

H 2 PH0 3 , phosphorous acid. H 4 P 2 7 , pyrophosphoric acid. 

HPH 2 2 , hypophosphorous acid. HP0 3 , metaphosphoric acid. 

When hypophosphorous acid is exposed to the air, oxygen is 
absorbed and phosphorous acid results ; by prolonged exposure 
more oxygen is absorbed and phosphoric acid is obtained. When 
phosphoric acid — or rather, for distinction, orthophosphoric acid — 
is heated, every two molecules yield the elements of a molecule of 
water, and pyrophosphoric acid results ; by prolonged exposure to 
heat more water is evolved and metaphosphoric acid is obtained. 
These differences will be further evident if the formulae be written 
empirically, nearly all being doubled, thus : 

H 6 P 2 4 , hypophosphorous acid. 
H 6 P 2 6 , phosphorous acid. 
H P O 1 phosphoric acid, or 

6 2 8 ' { orthophosphoric acid. 
H 4 P 2 O v , pyrophosphoric acid. 
H 2 P 2 6 , metaphosphoric acid. 

Or thus : 

phosphoric acid 
H 6 P 2 8 
phosphorous acid /\ pyrophosphoric acid 
H 6 P 2 6 / \ H 4 P 2 7 

hypophosphorous acid/ \ metaphosphoric acid 

H 6 P 2 4 . / \ H 2 I 

From the central compound, ordinary phosphoric acid, the acids of 
phosphorus differ by regularly diminishing proportions of the ele- 
ment oxygen, the varieties of phosphoric acid by regularly dimin- 
ishing proportions of the elements of water. 

Prepare phosphorous acid by exposing a moist stick of phos- 
phorus to the air ; a thin stream of heavy white vapor falls, 
which contains the acid in question. A simple method of col- 
lection is to place the stick in an old test-tube having a hole in 
the bottom, to support this tube by a funnel or otherwise, the 
neck of the funnel being supported in a bottle, test-glass, or 
tube, at the bottom of which is a little water. Or phosphorous 
oxide, P 4 6 , may first be obtained by heating phosphorus in a 



PYROPHOSPHATES. 353 

tube, through which a slow current of air is drawn, condensing 
the fumes in a U-tube surrounded by a freezing mixture, and 
then decomposing the oxide by water. Or chlorine is passed 
through phosphorus melted under water : PC1 3 + 3H 2 = 
P(HO) 3 + 3HC1. Having collected some phosphorous acid, 
apply the various tests already alluded to under Hypophos- 
phorous Acid, first carefully neutralizing the phosphorous acid 
by an alkali. The means by which the varieties of phosphoric 
acid are distinguished have been given under Metaphosphoric 
Acid. 

Other soluble phosphites are prepared by neutralizing phos- 
phorous acid with alkalies, and the insoluble phosphites by 
double decomposition. 

Associated with phosphorous acid prepared as above stated there 
is said to be an acid of the formula H 2 P0 3 , termed hypophosphoric 
acid. Its anhydride would be P 2 4 . 

It is interesting to note that during the oxidation of phosphorus 
in moist air, not only are phosphoric, hypophosphoric, and phos- 
phorous acids formed, but also ozone (0 3 ), hydrogen peroxide 
(H 2 2 ), and a small quantity of ammonium nitrate (NH 4 N0 3 ). 

Pyrogallic Acid. — See Tannic Acid. 

Pyrophosphoric Acid (H 4 P 2 0) 7 and other Pyrophos- 
phates.— Heat ordinary sodium phosphate (Na 2 HP0 4 ,12H 2 0) 
in a crucible ; water of crystallization is first evolved, and dry 
phosphate (Na 2 HP0 4 ) remains. Further heat to redness ; two 
molecules yield one of water, while a salt having new proper- 
ties is obtained : 2Na 2 HP0 4 — H 2 = Na 4 P 2 7 . It is termed 
sodium pyrophosphate, in allusion to its origin (nop, pur, fire). 
From its solution in water it may be obtained in prismatic crys- 
tals (Na 4 P 2 O 7 ,10H 2 O), Sodii Pyrophosphas, U. S. P., Pyrophos- 
phate of Sodium, or Sodium Pyrophosphate. Phosphoric acid 
itself is similarly affected by heat : 2H 3 P0 4 — H 2 = H 4 P 2 7 
(pyrophosphoric acid), though metaphosphoric acid is also 
formed. Other pyrophosphates are similarly produced, or by 
double decomposition and precipitation, or by neutralizing pyro- 
phosphoric acid by an oxide, hydrate, or carbonate. Ferri Pyro- 
phosphas Solubilis, U. S. P., is official. 

Tests. — To solution of a pyrophosphate add solution of silver 
nitrate ; a dense white precipitate falls (silver pyrophosphate, 
Ag 4 P 2 7 ), differing much in appearance from the white gelat- 
inous silver metaphosphate or the yellow orthophosphate. To 
pyrophosphoric acid or to a pyrophosphate mixed with acetic 
acid add an aqueous solution of albumen (white of egg) ; no 



354 SALTS OF RARER ACIDULOUS RADICALS. 

precipitate occurs. Metaphosphoric acid, it will be remem- 
bered, gives a white precipitate with albumen. 



QUESTIONS AND EXERCISES. 

What are the sources of lactic acid ?— How is lactic acid usually pre- 
pared ?— Name some of the plants in which malic acid is found. — Whence 
is meconic acid derived ? — By what process may meconic acid be isolated ? 
— Which is the best test for the meconic radical ?— Distinguish meconates 
from sulphocyanates. — Give the mode of manufacture of hypophosphites. 
— How is phosphoretted hydrogen prepared? — By what ready method 
may metaphosphoric acid be obtained for experimental purposes? — Name 
the tests for metaphosphates. — How may meta- or pyro -phosphoric acid 
be converted into orthophosphoric acid ? — Describe the preparation of 
phosphorous acid. — State the relations of the acids of phosphorus to each 
other.— How are the pyrophosphates prepared ?— Define, by formulae, 
metaphosphates, pyrophosphates, orthophosphates, phosphites, and hypo- 
phosphites. — Mention the tests by which meta-, pyro-, and ortho-phos- 
phates are analytically distinguished. — How are hypophosphites and 
phosphites detected ? 

Silicic Acid (H 4 Si0 4 ) and other Silicates. — Silicates of various 
kinds are among the commonest of minerals. The various clays 
are aluminium silicates ; the volcanic substance termed pumice-stone 
is a porous aluminium and alkali-metal or alkaline-earth metal 
silicate ; meerschaum is an acid magnesium silicate : the ordinary 
sandstones are chiefly silica ; sand, flint, quartz, agate, chalcedony, 
and opal are silicic anhydride or silica (Si0 2 ). Tripoli, a polishing 
powder now found in many other countries than Tripoli, and con- 
sisting of infusorial skeletons, is nearly pure silica. Bath brick, 
used in knife-polishing, is a silico-calcareous deposit found in the 
estuary at Bridgewater and other places. Tourmalines, plates of 
which, cut parallel to the axis of a crystal, are used as polarizers or 
analyzers in microscopy, are all aluminium silicates with varying 
iron, copper, manganese, etc. silicates. Asbestos, or amianth, is a 
fibrous calcium and magnesium silicate, the length of the fibres 
being from less than one inch to five feet. A single silk-like fibre 
can easily be fused, but even in very small masses and for all prac- 
tical purposes asbestos is infusible, and of course incombustible. It 
is also a bad conductor of heat. It is already largely used in pack- 
ing piston-rods and joints and for steam apparatus generally ; as a 
covering for boilers to prevent loss of heat by radiation ; and for so 
lining ceilings, floors, and other partitions as to render rooms, etc. 
fireproof. Artificial acid, and therefore insoluble, silicates are 
familiar under the forms of glass' and earthenware. Common Eng- 
lish window-glass is usually calcium, sodium, and aluminium sili- 
cate ; French glass, calcium and sodium silicate ; Bohemian, chiefly 
potassium and calcium silicate ; English flint or crystal glass for 
ornamental, table, and optical purposes is mainly potassium and 
lead silicate. Earthenware is mostly aluminium silicate (clay), 
with more or less of the more fusible silicates — namely, those of 



SILICATES. 355 

calcium, sodium, and potassium, and in the commoner forms, iron 
silicate. The various kinds of porcelain (China, Sevres, Meissen, 
Berlin, English), Wedgwood-ware, and stoneware are varieties of 
earthenware. Kaolin, or China clay, which is disintegrated fel- 
spar, not more common in China than in Devonshire and Cornwall, 
is the clay which yields the finest translucent porcelain. Crucibles, 
bricks, and tiles are clay-silicates. Fire-clay contains excess of silica 
and very small proportions of the fusible silicates ; hence its refrac- 
tory character. Mortar is essentially calcium silicate. Portland, 
Roman, and other " hydraulic" cements* are calcium silicates with 
more or less aluminium silicate. 

Mix together a few grains of powdered flint or sand with 
about five or six times its weight of sodium carbonate and an 
equal quantity of potassium carbonate, and fuse a little of the 
mixture on platinum-foil in the blowpipe flame ; the product is 
an alkaline, and therefore soluble, silicate, a kind of soluble glass. 
Boil the foil in water for a few minutes ; filter ; to a portion 
add excess of hydrochloric acid, evaporate the solution to dry- 
ness, and again boil the residue in water and acid ; silicon oxide, 
silicic anhydride, or silica (Si0 2 ) remains as a light, flaky, in- 
soluble powder. 

The soluble glass or glass liquor of trade commonly contains 10 
or 12 per cent, of soda (NaHO) to 20 or 25 per cent, of silica (Si0 2 ). 
"When of sp. gr. 1.300 to 1.400 it satisfies official requirements 
{Liquor Sodii Silicatis, Solution of Sodium Silicate, U. S. P.). 

The foregoing operation constitutes the test for silicates. By 
fusion with alkali the silicate is decomposed and a soluble alkaline 
silicate formed. On addition of acid, silicic acid (H 4 Si0 4 ) is set 
free, but remains in solution if the fluid is not too strong. The 
heat subsequently applied eliminates water and reduces the silicic 
acid to silica (Si0 2 ), which is insoluble in water or acid. By the 
addition of hydrochloric acid to soluble glass, and removal of the 
resulting alkaline chloride and excess of hydrochloric acid by dial- 
ysis (a process to be subsequently described), a pure aqueous solu- 
tion of silicic acid may be obtained ; it readily changes into a gelat- 
inous mass of silicic acid. Possibly some of the natural crystallized 
varieties of silica may have been obtained from the silica contained 
in such an aqueous solution, nearly all waters yielding a small 
quantity of silica when treated as above described. 

A variety of silicic acid (H 2 Si0 3 ), sometimes termed diabasic to 
distinguish it from the normal or tetrabasic acid (H 4 Si0 4 ), results 
when the aqueous solution of the latter is evaporated in vacuo. 

Siliciuretted hydrogen, or silicon hydride (SiH 4 ), is a sponta- 
neously inflammable gas formed on treating magnesium silicide 
with hydrochloric acid. It is the analogue of light carburetted 
hydrogen or methane (CH 4 ). A liquid silicon chloride (SiCl 4 ) 

* For an article on " Cements " generally see Pharmaceutical Journal 
for April 17, 1880. 



356 SALTS OF RARER ACIDULOUS RADICALS. 

analogous to carbon tetrachloride (CC1 4 ) and a gaseous fluoride 
(SiF 4 ) also exist. 

Many other analogies are traceable between the elements silicon 
and carbon, including, perhaps, boron, especially amongst their 
organic compounds. 

Succinic Acid (H 2 C 4 H 4 4 ). — Amber (Succinum) is a resin usually 
occurring in association with coal and lignite. From the fact that 
fragments of coniferous fruit are frequently found in amber, and 
impressions of bark on its surface, it is considered to have been an 
exudation from a species of Pinus now probably extinct. Heated 
in a retort, amber yields, first, a sour aqueous liquid containing 
acetic acid, and another characteristic body appropriately termed 
succinic acid; secondly, a volatile liquid known as oil of amber 
{Oleum Succini, U. S. P. 1880), resembling the oil yielded by most 
resinous substances under similar circumstances ; and, thirdly, a 
pitchy residue allied to asphalt. The succinic acid is a normal 
constituent of the amber ; the acetic acid is produced during distil- 
lation. Succinic acid has also been found in wormwood, in several 
pine resins, and in certain animal fluids, such as those of hydatid 
cysts and hydrocele. It may be obtained artificially from butyric, 
stearic, or margaric acid by oxidation. Tartaric, malic, and succinic 
acids are also convertible the one into the other. 

Succinates are neutral (R/ 2 C 4 H 4 4 ) and acid (R/HC 4 H 4 4 ) ; a 
potassium and hydrogen succinate (KHC 4 H 4 4 ,H 2 C 4 H 4 4 ,H 2 0), 
analogous to the superacid oxalate, salt of sorrel, also exists. 
Soluble succinates give a bulky brown precipitate with neutral 
ferric chloride, only less voluminous than ferric benzoate ; a white 
precipitate with lead acetate, soluble in excess of either reagent ; 
with silver nitrate a white precipitate after a time ; with barium 
chloride no precipitate at first, but a white one (barium succinate) 
on the addition of ammonia and alcohol. Succinates are distin- 
guished from benzoates by the last-named reaction and by not 
yielding a precipitate on the addition of acids. {Vide p. 337.) 

SULPHOCYANIC ACID (HCNS) AND OTHER SlJLPHOCYAN- 

ates. — Boil together sulphur and solution of potassium cyan- 
ide ; solution of potassium sulphocyanate (KCNS) is formed. 
Warm the liquid, add hydrochloric acid till it faintly reddens 
litmus-paper, and filter ; any potassium sulphide is thus decom- 
posed, and the solution may then be used for the following re- 
actions. The salt readily crystallizes. 

Tests. — To a small portion of the solution add a ferric salt 
(Fe 2 Cl 6 ) ; a deep blood-red solution (ferric sulphocyanate) is 
formed. To a portion of the red liquid add a little hydro- 
chloric acid ; the color is not discharged (ferric meconate, a salt 
of similar tint, is decomposed by hydrochloric acid). In the 
acid liquid place a fragment or two of zinc ; sulphuretted hydro- 
gen is evolved and the red color disappears. 



SULPHOCYANATES. 357 

To another portion of the ferric sulphocyanate add solution 
of corrosive sublimate ; the color is at once discharged (ferric 
meconate is unaffected by corrosive sublimate). The ferric is 
the best test of the presence of a sulphocyanate, and indirectly 
is also a good test of the presence of hydrocyanic acid or cyan- 
ogen (see p. 284). Solutions of pure ferrous salts are not col- 
ored by the solution of sulphocyanate. Red ferric acetate is 
decomposed by ebullition. Neither the ferric acetate nor the 
meconate yields its color to ether, but on shaking ferric sulpho- 
cyanate solutions with ether the latter takes up the salt and 
becomes of a purple color. 

To solution of a sulphocyanate add solution of mercuric 
nitrate ; mercuric sulphocyanate is precipitated as a white 
powder. 

Pharaoh' 1 s Serpents. — Mercuric sulphocyanate, thoroughly washed 
and made up into a little cone, forms the toy termed Pharaoh's ser- 
pent. It readily burns when ignited, the chief product being a 
light solid matter (mellon, C 9 N 13 , and melam, C 3 H 6 N 6 ) which issues 
from the cone in a snake-like coil of extraordinary length. The 
other products are mercuric sulphide (of which part remains in the 
snake and part is volatilized), nitrogen, sulphurous and carbonic 
acid gases, and vapor of metallic mercury. (For details concerning 
the economical manufacture of sulphocyanates see Pharmaceutical 
Journal, 2d series, vol. vii. p. 581 and p. 152.) 

The sulphocyanic radical (CNS) is often termed sulphocyanogen 
(Scy), and its compounds regarded as sulphocyanides. Saliva con- 
tains sulphocyanates. 

Tannic Acid, Gallotannic Acid, or Tannin. — Digallic Acid 
(Acidum Tannicum, U. S. P., C u H 10 O 9 ). — This is a very common 
astringent constituent of plants, but is contained in largest quan- 
tity in galls (excrescences on the oak formed by the puncture and 
deposited ova of an insect). English galls contain from 14 to 28 
per cent, of tannic acid; Aleppo galls (Galla, U. S. P.), 25 to 65. 
It is present also in the white oak (Quercus Alba, U. S. P.). 

Gallotannic acid, C 6 H 2 (OH) s COO-C 6 H 2 (OH) 2 COOH. 
Gallic acid (p. 360), C 6 H 2 (OH) 3 COOH. 

Process. — " Expose powdered galls [about an ounce is suf- 
ficient for the purpose of study] to a damp atmosphere for 
two or three days, and afterward add sufficient ether to form 
a soft paste. Let this stand in a well-closed vessel for twenty- 
four hours ; then, having quickly enveloped it in a linen cloth, 
submit it to strong pressure, so as to separate the liquid por- 
tion, which contains the bulk of the tannin in solution. Re- 
duce the pressed cake to powder, mix it with sufficient ether, 
to which one-sixteenth of its bulk of water has been added, 
16* 



358 SALTS OF RARER ACIDULOUS RADICALS. 

to form again a soft paste, and press this as before. Mix the 
expressed liquids, and expose the mixture to spontaneous evap- 
oration until, by the aid subsequently of a little heat, it has 
acquired the consistence of a soft extract ; then place it on 
earthen plates or dishes and dry it in a hot-air chamber at a 
temperature not exceeding 212° F." 

The resulting tannic acid occurs in " pale yellow vesicular 
masses or thin glistering scales, with a strongly astringent 
taste and an acid reaction, readily soluble in water and recti- 
fied spirit, very sparingly soluble in pure ether, though soluble 
in the ethereal fluid used in the foregoing process — a fluid 
which is really a mixture of true ether, water, and alcohol 
(both the latter contained in the common " ether ") and a 
little added water also. 

Medicinal Uses. — Tannic acid is very soluble in water, and in this 
form is usually administered in medicine. Its official (British) prep- 
arations are Glycerinum Acidi Tannici, Suppositoria Acidi Tannici, 
Suppositoria Acidi Tannici cum Sapone, and Trochisci Acidi 
Tannici. The preparations of the United States Pharmacopoeia are 
Collodium Stypticum, 20 grm. in 100 cc. ; Glyceritum Acidi Tannici, 
20 per cent. ; Trochisci Acidi Tannici, 0.06 grm. in each ; and 
Unguentum Ac di Tannici, 20 per cent. 

Tests. — To an aqueous solution of tannic acid add aqueous 
solution of gelatin ; a yellowish- white flocculent compound of 
the two substances is precipitated. 



-The above reaction also serves to explain the chemical 
principle involved in tanning — the operation of converting skin into 
leather. In that process the skin is soaked in infusion of oak-bark 
( Quercus Cortex, B. P.), the tannic acid of which, uniting with the 
gelatinous tissues of the skin, yields a compound very well repre- 
sented by the above precipitate. The outer bark of the oak con- 
tains little or no tannic acid, and is commonly shaved off from the 
pieces of bark which are large enough to handle ; useless coloring- 
matter is thus also rejected. Other infusions and extracts besides 
that of oak-bark (chiefly catechu, sumach, and valonia) are largely 
used by tanners ; if used alone, these act too quickly and give a 
harsh, hard, less durable leather. The tannic acid of these prepara- 
tions is probably slightly different from that of oak-bark. 

To an aqueous solution of tannic acid add a neutral solution 
of a ferric salt ; dark bluish-black ferric tannate is slowly pre- 
cipitated. This is an excellent test for the presence of tannic 
acid in vegetable infusions. The precipitate is the basis of 
nearly all black writing-ink. Ferrous salts give at first only 
a slight reaction with tannic acid, but the liquid gradually 
darkens : characters written with a liquid of this kind, of 



TANNATES. 359 

proper strength, become quite black in a few hours, and are 
very permanent. 

To an aqueous solution of tannic acid add solution of tartar 
emetic ; antimony tannate is precipitated. This reaction and 
that with gelatin are useful in the quantitative estimation of 
the amount of tannic acid in various substances, the separation 
of the gelatin tannate being much promoted by previously add- 
ing some heavy neutral powder, such as barium sulphate, and 
well stirring while adding the gelatin. 

Tannic acid, as it occurs in oak-bark, is said to be a glucoside ; 
that is, like several other substances, it yields glucose (grape-sugar) 
when boiled with dilute sulphuric or hydrochloric acid, the other 
product being gallic acid. Possibly, however, the sugar is not a 
necessary constituent of the tannin, certainly not of all of them. 

Catechu (Catechu, B. P.), Gambler or Terra Japonica, an extract 
of the Uncaria Gambler ; as well as the true Catechu Cutch, or 
Terra Japonica, an extract from the Acacia Catechu (Catechu, 
U. S. P., Catechu nigrum, P. I.) and A. Suma; East Indian Kino 
(Kino, U. S. P.), from the Pterocarpus marsupium ; also Bengal or 
Butea Kino, from the palas or dhak tree, Butea frondosa (Butece 
Gummi vel Kino Bengalensis, P. I.) ; Botany Bay or Australian 
kinos from various species of Eucalyptus or blue-gum trees ; and 
some other vegetable products — contain a variety of tannic acid 
(mimotannic acid), which gives a greenish precipitate with neutral 
solutions of ferric salts. According to Paul and Kingzett, it yields, 
when decomposed, unfermentable sugar and an acid different to 
ordinary gallic acid. Catechu and gambier also contain catechuic 
acid or catechin, C 13 H 12 5 , a body occurring in minute colorless 
acicular crystals, and, like mimotannic acid, affording a green preci- 
pitate with ferric salts. 

Bael-fruit (Belce Fruetus, U. S. P.), from the JEgle Marmelos, is" 
said to owe its power as a remedy for dysentery and diarrhoea to a 
variety of tannic acid, but this is questionable. About 10 per 
cent, of tannic acid is contained in the leaves of Castanea dentata 
(Castanea, U. S. P.), the tree yielding edible chestnuts. The rind 
of the fruit of the pomegranate (Punica granatum) ( Granati Cortex, 
P. 1.) contains tannic acid. The astringency of pomegranate-root 
bark (Granati Radicis Cortex, B. P. and P. I., Granatum, U. S. P.) 
is due to a tannic acid (its anthelmintic properties probably to a 
resinoid matter, or possibly to what Tanret states to be a liquid 
alkaloid, pelletierine, C 16 H 30 N 2 O 2 ). A tannic acid also probably 
gives the astringency to logwood (Hcematoxylon, TJ. S. P.). Rhatany- 
root bark (Krameria, TJ. S. P.) contains about 20 per cent, of tannic 
acid, its active astringent principle ; rhubarb-root about 9 per cent. 
Bearberry-le&ves (Uva Ursi, TJ. S. P.) owe most of their therapeutic 
power to about 35 per cent, of tannic acid. (The cause of their 
influence on the kidneys is not yet traced.) They also contain 
arbutin, a crystalline glucoside. Larch-bark (Laricis Cortex, B. P.), 
the inner bark of Pinus Larix or Larix Europcea, contains, accord- 



360 SALTS OF RARER ACIDULOUS RADICALS. 

ing to Stenhouse, a considerable amount of a tannic acid giving 
olive-green precipitates with iron salts, and larixin and larixinic 
acid (C 10 H 10 O 5 ), a somewhat bitter substance. Areca-nuts or betel- 
nuts, from the Areca palm (Areca Catechu), besides the alkaloid 
arekane (Bombelon), contain a very active alkaloid, arecoline, 
C 8 H 13 N0 2 (Jahns), said to be the vermifugal principle ; arecaine, an 
inert alkaloid (Jahns), and, according to Fluckiger and Hanbury, 
about 16 per cent, of " tannic matter." The extract of the fruit of 
gab, or Diospyros embryopteris (Diospyri Fructus, P. I.) is a 
powerful astringent containing tannic acid. The rhizome (Gera- 
nium, U. S. P.) of Geranium maculatum, spotted cranesbill or arum- 
root, contains both tannic and gallic acids. Sumac, or shumac, or 
sumach, the leaves and stalks of various species of Rhus, chiefly 
Rhus coriaria, contains ordinary tannic acid and gallic acid. The 
fruit of sumach (Rhus glabra, U. S. P.) contains tannic and much 
malic acid. The bark of Prinos verticillatus, the black alder or 
winterberry, contains tannin and a bitter principle. The principal 
constituent of the bark of the root of Rubus villosus, or high black- 
berry, and of R. canadensis and R. trivialis (Rubus, U. S. P.), is 
tannic acid. 

Gallic Acid (H 3 C 7 H 3 3 ,H 2 0) (Acidum Gallicimi, U. S. P.) 
occurs in small quantity in oak-galls and other vegetable sub- 
stances, but is always prepared from tannic acid. Gallic acid 
forms slender acicular, fawn-colored crystals, soluble in one 
hundred and eighteen times their weight of cold or three of 
boiling water, freely in spirit, sparingly in ether. 

" Boil 1 part of coarsely powdered galls with 4 fluid parts 
of diluted sulphuric acid for half an hour, then strain through 
calico while hot ; collect the crystals that are deposited on 
cooling, and purify these with animal charcoal and repeated 
crystallization." 

Test. — To an aqueous solution of gallic acid add a neutral 
solution of a ferric salt ; a bluish-black precipitate of ferric 
gallate falls, similar in appearance to ferric tannate. Ferrous 
salts also are blackened by gallic acid. To more of the solu- 
tion add an aqueous solution of gelatin ; no precipitate occurs. 
By the latter test gallic is distinguished from tannic acid. 

Pyrogallic Acid, or Pyrogallol, C 6 H 3 (OH) 3 . — This substance sub- 
limes in light feathery crystals when gallic acid is heated. It is 
very soluble in water, alcohol, and ether. Or it may be formed by 
heating gallic acid with three or four times its weight of glycerin to 
a temperature of 190° or 200° C. for a short time, until carbonic 
acid ceases to be evolved. Longer heating at lower temperatures is 
not equally effective, and below 100° C. probably no pyrogallol is 
produced (Thorpe). To an aqueous solution add a neutral solution 
of a ferric salt ; a red color is produced which turns dark bluish on 
the addition of ammonia. To another portion add a ferrous salt ; a 



URATES. 361 

deep-blue color results. The aqueous solution of pyrogallol reduces 
solutions of silver, mercury, and gold salts in the cold. 

Test for the Three Acids. — To three separate small quantities 
of milk of lime in test-tubes add, respectively, tannic, gallic, 
and pyrogallic acids ; the first slowly turns brown, the second 
more rapidly, while the pyrogallic mixture at once assumes a 
beautiful purplish-red color changing to brown. These reac- 
tions are characteristic ; they are accompanied by absorption 
of oxygen from the air. 

Use of Pyrogallic Acid in Gas Analysis. — A mixture of pyrogallic 
acid and solution of potash absorbs oxygen with such rapidity and 
completeness that a strong solution of each, passed up successively 
by a pipette into a graduated tube containing air or other gas, forms 
an excellent means of estimating free oxygen. The value of this 
method may be roughly proved by pouring a small quantity of each 
solution into a phial, immediately and firmly closing its mouth with 
a cork, thoroughly shaking the mixture, and then removing the 
cork under water : the water rushes in and occupies about one-fifth 
of the previous volume of air, indicating that the atmosphere con- 
tains one-fifth of its bulk of oxygen. The small amount of carbonic 
acid gas present in the air is also absorbed by the alkaline liquid ; 
in delicate experiments this should be removed by the alkali before 
the addition of pyrogallic acid. 

Toxicodendric Acid is the volatile, excessively acrid, and poisonous 
principle of the poison oak or poison ivy, the fresh leaves of which 
are official (Rhus toxicodendron, U. S. P.). 

Uric Acid (H 2 C 5 H 2 N 4 3 ) and other Urates. — Acidulate 
a few ounces of human urine with hydrochloric acid, and set 
aside for twenty -four hours : a few minute crystals of uric acid 
will be found adhering to the sides and bottom of the vessel 
and floating on the surface of the liquid. 

Microscopical Test. — Remove some of the floating particles 
by a slip of glass, and examine by a powerful lens or micro- 
scope ; the chief portion will be found to be in yellowish semi- 
transparent crystals, more or less square, two of the sides of 
which are even and two very jagged ; but other forms are com- 
mon. (See the lithographs in the section on Urinary Sedi- 
ments.) 

Chemical Test. — Collect more of the deposit, place in a 
watch-glass or small white evaporating-dish, remove adherent 
moisture by a piece of blotting- or filter-paper, add a drop or 
two of strong nitric acid, and evaporate to dryness ; the residue 
will be red. When the dish is cold add a drop of solution of 
ammonia ; a purplish-crimson color results. The color is deep- 
ened on the addition of a drop of solution of potash. 



362 SALTS OF RARER ACIDULOUS RADICALS. 

Notes. — Uric acid (or lithic acid) and sodium, potassium, calcium, 
and ammonium urates (or lithates) are common constituents of 
animal excretions. Human urine contains about 1 part of urate 
(usually sodium urate) in 1000. When more than this is present 
the urate is often deposited as a sediment in the excreted urine, 
either at once or after standing a short time. Uric acid or other 
urate is also occasionally deposited before leaving the bladder, and, 
slowly accumulating there, forms a common variety of urinary 

calculus. Some urates are not definitely crystalline, but, when 

treated with dilute nitric acid or a drop of solution of potash and 
then a drop or two of acetic acid, jagged microscopic crystals of uric 
acid are usually formed. All urates yield the crimson color when 
treated as above described. This color is due to a definite sub- 
stance, murexid, C 8 H 8 N 6 6 (from the murex, a shell-fish of similar 
tint, and from which the ancient and highly valued purple dye 
seems to have been prepared), and the test is known as the murexid 
test. The formation of murexid is due to the action of ammonia on 
alloxan (C 4 H 2 N 2 4 ,4H 2 0) and other white crystalline products of the 
oxidation of uric acid by nitric acid. Murexid is a good dye ; it 
may be prepared from guano (the excrement of sea-fowl), which 
contains a large quantity of ammonium urate. The excrement of 
the serpent is almost pure ammonium urate. 

Uric acid and the urates will again be alluded to in connection 
with the subject of Morbid Urine. 

Constitution of Uric Acid. — The physiological and pathological 
importance of uric acid has obtained for it great attention from 
chemists, a knowledge of its constitution being rightly regarded as 
amongst the most prominent of chemical desiderata. (For accounts 
of what has been done in this direction in recent years students of 
organic chemistry may consult the Pharmaceutical Journal, 3d 
Series, vol. xiv. p. 771 ; vol. xv. pp. 119 and 411 ; and vol. xviii. p. 
69. See also page 390.) 

Valerianic Acid, or Valeric Acid (HC 5 H 9 2 ), and 
other Valerianates. — In a test-tube place a few drops of 
amylic alcohol (fousel oil) with a little dilute sulphuric acid 
and a grain or two of red potassium chromate ; cork the tube, 
set aside for a few hours, and then heat the mixture ; valeri- 
anic acid, the hydrogen valerianate, of characteristic valerian- 
like odor, is evolved. 

Valerianic acid occurs in valerian-root in association with the 
essential oil from which it is apparently derived {vide Index), but is 
usually prepared artificially, by the foregoing process, from amylic 
alcohol, to which it bears the same relation as acetic acid does to 
common alcohol : 

C 2 H 5 HO + 2 = HC 2 H 3 2 + H 2 0. 
C 6 H u HO + 2 = HC 5 H 9 2 + H 2 0. 

Sodium Valerianate (NaC 5 H 9 2 ) (Sodii Valerianae, B. P.), 
the old valerianate of soda, is prepared from the valerianic acid 



VALERIANATES. 363 

and amyl valerianate obtained on distilling the mixture of 
amylic alcohol (4 fl. oz.), sulphuric acid (6J fl. oz. with 10 of 
water), and red potassium chromate (9 oz. in 70 of water).' The 
mixture should stand for several hours before heat is applied. 

2(K 2 Cr0 4 ,O0 3 ) -f 8H a S0 4 = 2(K 2 S0 4 ,O 2 3S0 4 ) + 8H 2 + 30 2 

Bed potassium Sulphuric Potassium and chromium Water. Oxygen, 

chromate. acid. sulphate (chrome alum). 

C 5 H n HO + 2 = HC 5 H 9 2 + H 2 

Amylic Oxygen. Valerianic Water, 

alcohol. acid. 

2C 6 H u HO + 2 = CsHnCVBA + 2H 2 

Amylic Oxygen. Amyl valerianate. Water, 

alcohol. 

The distillate (70 or 80 oz.) is saturated with soda, which not only- 
yields sodium valerianate with the free valerianic acid, but decom- 
poses the amyl valerianate produced at the same time, more sodium 
valerianate being formed and some amylic alcohol set free, according 
to the following equations : 

HC 5 H 9 2 + NaHO = NaC § H 9 2 + H 2 0. 

Valerianic Soda. Sodium Water, 

acid. valerianate. 

C 5 H u C 5 H 9 2 + NaHO = NaC 5 H 9 0° + C 5 H u HO. 

Amyl Soda. Sodium Amylic 

valerianate. valerianate. alcohol. 

From the solution of sodium valerianate (which should be 
made neutral to test-paper by careful addition of soda solution) 
the solid white salt is obtained by evaporation to dryness and 
cautious fusion of the residue. The mass obtained on cooling 
should be broken up and kept in a well-closed bottle. It should 
be entirely soluble in spirit. 

Other Valerianates, as zinc valerianate (Zinci Valerianae, 
U. S. P.) and Ferric Valerianate {Ferri Valerianas, U. S. P., 
Fe 2 6C 5 H 9 2 ), may be made by double decomposition of sodium 
valerianate with the sulphate or other salt of the metal the 
valerianate of which is desired, the new valerianate either pre- 
cipitating or crystallizing out. A hot solution of zinc sulphate 
(5f parts) and sodium valerianate (5 parts) in water (40 parts) 
gives a crop of crystals of zinc valerianate on cooling. 

Tests. — Heated with diluted sulphuric acid, valerianates of 
the metals give valerianic acid, which has a highly characteristic 
smell. Sodium valerianate thus treated, and the resulting oily 
acid liquid purified by agitation with sulphuric acid and distil- 
lation, furnishes valerianic acid, Dry ammonia gas passed into 
valerianic acid gives white lamellar crystals of Ammonium 
Valerianate {Ammonii Valerianas, NH^CsHgO^ U. S. P.). 

The amylic alcohol (C 5 II n HO) from which valerianates are pre- 



364 SALTS OF RARER ACIDULOUS RADICALS. 

pared may contain the next lower homologue, butylic alcohol 
(C 4 H 9 HO). ( Vide " Homology " in the Index.) This, during oxida- 
tion, will be converted into butyric acid (HC 4 H 7 2 ), the next lower 
homologue of valerianic acid (HC 5 H 9 2 ), and hence the various 
valerianates be contaminated by some butyrates. These are detected 
by distillation with diluted sulphuric acid and addition of solution 
of copper acetate to the distillate, which at once becomes turbid if 
butyric acid be present. In this reaction valerianic and butyric 
acids are produced by double decomposition of the valerian- 
ate and butyrate by the sulphuric acid, and distil over on the appli- 
cation of heat. On the addition of copper acetate (Cu2C. 2 H 3 2 ) copper 
butyrate (Cu2C 4 H 7 2 ,H 2 0) is formed, and, being almost insoluble in 
water, is at once precipitated or remains suspended, giving a bluish- 
white opalescent liquid. Copper valerianate (Cu2C 5 H 9 2 ) is also 
formed after some time, but is far more soluble than the butyrate, 
and only slowly collects in the form of greenish oily drops, which 
gradually pass into greenish-blue hydrous crystalline copper vale- 
rianate (Larocque and Huralt). 

Vanillic Acid (HC 8 H 7 3 ), or Vanillin (C 8 H 8 3 ),or Methylpro- 
tocatechuic Aldehyde (C 7 H 5 CH 3 3 ), is the body to which is due the 
odor and flavor of vanilla. It also occurs in Siam benzoin, Rosa 
canina, etc. The white crystals commonly found on vanilla (the 
prepared unripe pods of Vanilla planifolia), previously termed 
vanillin, were found by Carles to be a weak acid. It occurs in 
vanilla to the extent of from 1J to 3 per cent. Vanillin has in 
recent years been prepared artificially by Tiemann and Haarman 
from coniferin, a glucoside existing in the sapwood of pines. The 
body remaining after the removal of glucose from coniferin, or, in- 
deed, coniferin itself, by action of a mixture of red potassium chro- 
mate and sulphuric acid, yields the vanillin. It also may be ob- 
tained by a series of reactions starting from that of carbonic acid 
on potassium carbolate ; also from the eugenol of oil of cloves. By 
action of hydrochloric acid vanillin yields methyl chloride and pro- 
tocatechuic aldehyde. Such reactions will be better understood when 
the pupil has studied succeeding sections on what is commonly 
termed Organic Chemistry. Artificial vanilla is less stable than 
natural vanillin, perhaps because with the latter is associated a 
preservative resin. 



QUESTIONS AND EXERCISES. 

What is the constitution of nitrites? — Mention a test for nitrites in 
potable waters. — Which nitrites are official? — Give the names of some 
natural and artificial silicates. — What is " soluble glass " ?— Distinguish 
between silica and silicic acid. — How are silicates detected ? — What is 
the quantivalence of silicon ? — Mention the sources, formulae, and analyt- 
ical reactions of succinates.— State the mode of manufacture and tests 
of sulphocyanates. — What proportion of tannic acid is contained m galls? 
— Describe the official process for the preparation of tannic acid. — Ex- 
plain the chemistry of " tanning." — Enumerate the tests for tannic acid. 
— What is the assumed constitution of tannic acid? — Mention official 
substances other than galls whose astringency is due to tannic acid. — 



DETECTION OP ACIDULOUS RADICALS. 365 

How is gallic acid prepared? — By what reaction is gallic distinguished 
from tannic acid ? — Mention the characteristic properties of pyrogallic 
acid. — Explain the murexid test for uric acid. — Describe the artificial 
preparation of valerianic acid and other valerianates, giving diagrams 
or equations. — What is the formula of valerianic acid ? — How are buty- 
rates detected in presence of valerianates? 



DETECTION OF THE ACIDULOUS RADICALS 
OF SALTS SOLUBLE IN WATER. 

Analytical operations may now be resumed, the detection of acidu- 
lous radicals being practised for two or three days, and then full 
analyses made, both for basylous and acidulous radicals. To this 
end a few compounds of stated metals (potassium, sodium, or am- 
monium) should be placed in the hands of the practical student for 
examination according to the following paragraphs and tables. 
Mixtures in which both basylous and acidulous radicals may be 
sought should then be analyzed. 

In examining salts soluble in water, and concerning which no 
general information is obtainable, search must first be made for any 
basylous radicals by the appropriate methods. ( Vide pp. 224 or 
257-262.) Certain metals having been thus detected, a little reflec- 
tion on the character of their salts will at once indicate what acidu- 
lous radicals may be and what cannot be present. Thus, for in- 
stance, if the substance under examination is freely soluble in water 
and lead is found, only the nitric and acetic radicais need be sought, 
none other of the lead salts than nitrate or acetate being freely 
soluble in water. Moreover, the salt is more likely to be lead 
acetate than nitrate, for two reasons : the former is more soluble 
than the latter, and is by far the commoner salt of the two. Medical 
and pharmaceutical students have probably, in dispensing, already 
learned much concerning the solubility of salts, and whether a salt 
is rarely employed or is in common use. And, although but little 
dependence can be placed on the chances of a salt being present or 
absent according to its rarity, still the point may have its proper 
weight. If in a mixture of salts, ammonium, potassium, and mag- 
nesium have been found associated with the sulphuric, nitric, and 
hydrochloric radicals, and we are asked how we suppose these bodies 
may exist in the mixture, it is far more in accordance with common 
sense to suggest that sal-ammoniac, nitre, and Epsom salt were 
originally mixed together than to suppose any other possible combi- 
nation. Such appeals to experience regarding the solubility or 
rarity of salts cannot be made by any one not previously acquainted, 
or insufficiently acquainted, with the characters of salts ; in such 
cases the relation of a salt to water and acids can be ascertained by 
referring to the following table (p. 368) of the solubility or insolu- 
bility of about five hundred of the common and rarer salts met with 
in chemical operations. 

The opposite course to the above (namely, to ascertain what acidu- 
lous radicals are present in a mixture, and then to appeal to experi- 



366 DETECTION OF ACIDULOUS RADICALS. 

ence to tell what basylous radicals may be and what cannot be pres- 
ent) is impracticable ; for acidulous radicals cannot be separated out, 
one after the other, from one and the same quantity of substance by 
a similar treatment to that already given for basylous radicals. 
Indeed, such a sifting of acidulous radicals could scarcely be accom- 
plished at all or only by a vast deal of labor. The basylous radicals 
must therefore first be detected. 

Even when the basylous radicals have been found, the acidulous 
radicals which may be present must be sought for singly, the only 
additional aid which can be brought in being the action of sulphuric 
acid, a barium salt, a calcium salt, silver nitrate, and ferric chloride 
on separate small portions of the solution under examination, as 
detailed in the second of the following tables. 

Practical Analysis. 

Commence the analysis of an aqueous solution of a salt or 
salts, the basylous radicals in which are known, by writing out 
a list of the acidulous radicals which may be, or, if more 
convenient, of those which cannot be, present. To this end 
consult the following table (p. 368) of the solubility of salts 
in water. Look for the name of the metal of the salt in the 
vertical column ; the letters S and I indicate which salts are 
soluble and which insoluble in water, an asterisk attached to 
the S meaning that the salt is slightly soluble. The acidulous 
part of the name is given in the top line of the table. All the 
names are in alphabetical order, for facility of reference. 

Some of the salts marked as insoluble in water are soluble in 
aqueous solutions of soluble salts, a few forming soluble double 
salts. To characterize salts as soluble, slightly soluble, or insoluble 
only roughly indicates their relation to water : on the one hand, very 
few salts are absolutely insoluble in water ; on the other, there is a 
limit to the solubility of every salt. 

If only one, two, or perhaps three given acidulous radicals can 
be in the liquid, test directly for it or them according to the re- 
actions given in the previous pages. If several may be present, 
pour small portions of the solution, rendered neutral if necessary 
by ammonia, into five test-tubes, and add respectively sulphuric 
acid, barium nitrate or chloride, calcium chloride, silver nitrate, 
and ferric chloride ; then considt the table on p. 369 in order to 
correctly interpret the effects these reagents may have produced. 

Remarks on the Table, p. 369. 

The first point of value to be noticed in connection with this table 
is one of a negative character — namely, if either of the reagents 
gives no reaction, it is self-evident that the salts which it decomposes 
with production of a precipitate must be absent. Then, again, if 



DETECTION OF ACIDULOUS RADICALS. 367 

the action of one of the reagents indicates the absence of certain 
acidulous radicals, those radicals cannot be amongst those precipi- 
tated by the other reagents ; thus, if the action of sulphuric acid 
points to the absence of sulphides, sulphites, carbonates, cyanides, 
and acetates, these salts may be struck out of the other lists, and the 
examination of subsequent precipitates be so far simplified. Or if 
the barium precipitate is soluble in hydrochloric acid and the calcium 
precipitate in acetic acid, neither sulphates nor oxalates can be 
present. Observing these and other points of difference, which will 
be seen on careful and thoughtful reflection, and remembering the 
facts suggested by a knowledge of what basylous radicals are present, 
one acidulous radical after the other may be struck off as absent or 
present, leaving only one or two as the objects of special experiment. 
Among the chief difficulties to be encountered will be the separation 
from each other of chlorides, bromides, iodides, and cyanides, or of 
tartrates from citrates, and confirmatory tests of the presence of cer- 
tain compounds. These may all be surmounted on referring back 
to the reactions of the various radicals, as described under their 
hydrogen salts, the acids. 

In rendering a solution neutral for the application of the various 
group-tests^ the necessary employment of any large amount of 
acid or of alkali must be noted, the presence of actual alkalies 
(that is, hydrates) or of acids themselves— -free acids, so called — 
respectively being thereby indicated. Free acids also betray them- 
selves by the abundant effervescence which results on the addition 
of a carbonate. 

Sulphuric acid, the first group-reagent, may itself yield, especially 
when heated with some solid substances, sulphurous acid or hydro- 
sulphuric acid (see p. 275) : hence the production of the latter acids 
from a diluted solution only is evidence of the presence of a sul- 
phide or sulphite. 

In the precipitate produced by barium chloride, the second group- 
reagent, the oxalic radical may be specially sought by the test de- 
scribed in the "note" on p. 275. 

Calcium chloride does not precipitate citrates readily or completely 
in the cold ; therefore the mixture should be filtered and the filtrate 
boiled ; calcium citrate then falls. Calcium tartrate is soluble in 
solution of ammonium chloride when quite freshly precipitated, but 
not after it has become crystalline. From their solution in ammo- 
nium chloride, calcium tartrate is mostly precipitated by ammonia, 
and citrate on boiling. 

The rarer acidulous radicals will very seldom be met with. Ben- 
zoates, hippurates (which give benzoic acid), hypochlorites, hyposul- 
phites, nitrites, and valerianates show themselves under the sul- 
phuric treatment. Ferrocyanides, ferricyanides, meconates, succin- 
ates, sulphocyanates, iannates, and gallates appear among the salts 
whose presence is indicated by ferric chloride ; formates, hypophos- 
phites, malates, and others by silver nitrate. Urates char when 
heated, giving an odor resembling that of burnt feathers. . 

In actual practice the analyst nearly always has some clue to the 
nature of rarer substances placed in his hands. 



368 



DETECTION OF ACIDULOUS RADICALS. 



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Cyanides, white. 

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Sulphites, white. 

Carbonates, white. 

Oxalates, white. 

Tartrates, white. 

Phosphates, yellow. 

Citrates, white. 
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370 ANALYSIS OF SALTS. 

If chromium and arsenum have been detected among the basylous 
radicals, those elements may be present in the form of chromates, 
arsenates, and arsenites, yielding with barium chloride yellow barium 
chromate and white barium arsenate and arsenite, and with silver 
nitrate red silver chromate, brown silver arsenate, and yellow silver 
arsenite. 



QUESTIONS AND EXEECISES. 

In analyzing an aqueous solution of salts, for which radicals would 
you first search, the basylous or the acidulous? and why? — In an aque- 
ous solution there have been found magnesium (Mg) and potassium (K), 
with the sulphuric radical (SO4) and iodine (I) ; state the nature of the 
salts which were originally dissolved in the water, and mention the 
principles which guide you to the conclusions. — Give a sketch of the 
method by which to analyze a neutral or only faintly acid aqueous 
liquid for the acidulous radicals of salts. In what stage of the process 
would the following salts be detected? a. Carbonates and sulphates. 
b. Oxalates, c. Tartrates and nitrates, d. Acetates and sulphites. 
e. Bromides and cyanides. /. Borates, g. Iodides and phosphates. 
h. Chlorates, oxalates, and acetates, i. Chlorides and iodides, j. Sul- 
phites, k. Sulphides, carbonates, and nitrates. I. Citrates and sul- 
phates. — Silver nitrate gives no precipitate in an aqueous solution ; 
what acidulous radicals may be present? — Barium chloride gives no 
precipitate in neutral solution, but silver nitrate a white ; what acidu- 
lous radicals are indicated ? — Ferric chloride produces a deep-red color 
in a solution, calcium chloride yielding no precipitate ; what salts may 
be present? and how may they be distinguished from each other? — Fer- 
ric chloride gives a black precipitate in a solution in which sulphuric 
acid develops no odor; to what is the effect due? 



ANALYSIS OF SALTS. 
SINGLE OR MIXED, SOLUBLE OR INSOLUBLE. 

Thus far, all material substances, especially those of pharma- 
ceutical interest, have been regarded as being definite compounds, 
and as having certain well-defined parts, termed, for convenience, 
basylous and acidulous respectively ; moreover, attention has been 
designedly restricted to those definite compounds which are soluble 
in water. But there are many substances having no definite or 
known composition, and of those having definite composition there 
are many having no definite or ascertained parts. Again, of those 
having definite composition, and whose constitution admits of the 
entertainment of theory, there are many insoluble in water. 

Chemical substances of whose composition or constitution little or 
nothing is at present known are chiefly of animal and vegetable 
origin, and figure in tables of analyses under the convenient col- 
lective title of " extractive matter ;" they are not of immediate 
importance, and may be omitted from consideration. 

Of substances which are definite in composition, but whose parts 
or radicals, if they have any, are unknown or imperfectly known, 



PRELIMINARY EXAMINATION. 371 

there are only a few (such as the alkaloids, amylaceous and saccha- 
rine matters, the glucosides, and the albumenoid, resinoid, and 
colorific substances) which have any considerable amount of med- 
ical or pharmaceutical interest ; these will be noticed subsequently. 
Definite compounds most frequently present themselves ; and of 
these by far the larger proportion (namely, the salts soluble in 
water) have already been fully studied. There remain, however, 
many salts which are insoluble in water, but which must be brought 
into a state of solution before they can be effectively examined. 
The next subject of laboratory work is, therefore, the analysis of 
substances which may or may not be soluble in water. This will 
involve no other analytical schemes than those which have been 
given, and will in only one or two cases increase the difficulty of the 
analysis of a precipitate produced by a group-reagent, but will give 
roundness, completeness, and a practical bearing to the reader's 
analytical knowledge. Such a procedure will at the same time 
bring into notice the methods by which substances insoluble in 
water are manipulated for pharmaceutical purposes or made avail- 
able for use as food by plants or as food and medicine by man and 
animals generally. g 

Preliminary Examination of Solid (chiefly Mineral) Salts. 

Before attempting to dissolve a salt for analysis, its appearance 
and other physical properties should be noted, and the influence of 
heat and strong sulphuric acid be ascertained. If the operator 
knows how to interpret what is thus observed, and to what extent 
to place confidence in the observations, he may more certainly 
obtain a high degree of precision in analysis, and will always gain 
some valuable negative information. But if he has only slight 
experience of the appearance and general properties of bodies, or 
has the habit of turning what should be inferences from tentative 
processes into foregone conclusions, he should omit the preliminary 
examination altogether, or only follow it out under the guidance of 
a judicious tutor ; for it is impracticable here to do more than hint 
at the results which may be obtained by such an examination, or to 
so adapt descriptions as to prevent a student allowing unnecessary 
weight to preconceived ideas. 

Whatever be the course pursued, short memoranda describing 
results should invariably be entered in the note-book. 

1. Examine the physical characters of the salt in various 
ways, but never, or only rarely and cautiously, by the palate, 
on account of the danger to be apprehended. 

If the salt is white, colored substances cannot be present ; if col- 
ored the tint may indicate the nature of the substance or of one of 
its constituents, supposing that the learner is already acquainted 
with the colors of salts. Close observation, aided perhaps by a 
lens, may reveal the occurrence in a pulverulent mixture of small 
crystals or pieces of a single substance 5 these should be picked out 
by a needle and examined separately. In a powder or roughly- 



372 GENERAL QUALITATIVE ANALYSIS. 

divided mixture of substances the process of sifting (through such 
sieves as muslin of different degrees of fineness) often mechanically 
separates substances, and thus greatly facilitates analysis. The 
body may present an undoubted metallic appearance, in which case 
only the metals existing under ordinary atmospheric conditions 
need be sought. Peculiarity in smell reveals the presence of am- 
monia, hydrocyanic acid, hydrosulphuric acid, etc. Between the 
fingers a substance is perhaps hard, soft, or gritty ; consequent 
inferences follow. Or the matter may be heavy, like the salts of 
barium or lead ; or light, like magnesium carbonate and hydrate ; 
or may be one of the pharmaceutical^ well-known class of "scale" 
preparations. 

2. Place a grain or two of the salt in a small dry test-tube 
or in a piece of ordinary tubing closed at one end, and heat it, 
at first gently, then more strongly, and finally, if necessary, by 
the blowpipe. 

Gases or vapors of characteristic appearance or odor may be 
evolved, such as iodine, nitrous fumes, sulphurous, hydrocyanic, or 
ammomacal gases. Much steam given off by a dry substance in- 
dicates either hydrates or salts containing water of crystallization. 
(A small quantity of interstitial moisture often causes heated crys- 
talline substances to decrepitate (from decrepo, I crackle) 5 that is, 
break up with slight explosive violence, owing to the expansive 
force of the steam suddenly generated.) A sublimate may result, 
due to salts of ammonium, mercury, or arsenum, to oxalic or ben- 
zoic acid, or to sulphur free or as a sulphide — a salt wholly volatile 
containing such substances only. The compound may blacken, 
pointing to the presence of organic matter, which, in common 
definite salts, will probably be in the form of acetates, tartrates, 
and citrates, or as common salts of the alkaloids morphine, quinine, 
strychnine, or as a starch, sugar, salicin, or in other definite or indef- 
inite forms common in pharmacy, and for which tests will be given 
in subsequent pages. If no charring occurs, the important fact is 
established that no organic matter is present, except cyanides, for- 
mates, or oxalates, which do not char. The residue may change 
color from presence or development of zinc oxide, iron oxide, etc., 
or melt from the presence of a fusible salt and absence of any large 
proportion of infusible salt, or be unaltered, showing the absence 
of any large amount of such substances. 

3. Place a grain or two of the salt in a test-tube, add a drop 
or two of strong sulphuric acid, cautiously smelling any gas 
that may be evolved ; afterward slowly heat the mixture, 
noticing the effect, and stopping the experiment when any sul- 
phuric fumes begin to escape. 

Iodine, bromine, and nitrous or chlorinoid fumes will reveal them- 
selves by their color, indicating the presence of iodides, bromides, 
iodates, bromates, nitrates, and chlorates. The evolution of a col- 
orless gas fuming on coming into contact with air and having an 



METHODS OF EFFECTING SOLUTION. 373 

irritating odor points to chlorides, fluorides, or nitrates. Gaseous 
products having a greenish color and odor of chlorine indicate chlo- 
rates, hypochlorites, or chlorides mixed with other substances. 
Slight sharp explosions betoken chlorates. Evolution of colorless 
gas may proceed from cyanides, acetates, sulphides, sulphites, car- 
bonates, or oxalates. Charring will be due to citrates, tartrates, or 
other organic matter. If neither of these effects is produced, most 
of the bodies are absent or only present in minute quantity. The 
substances apparently unaffected by the treatment are metallic 
oxides, borates, sulphates, and phosphates. 

4. Exposure of the substance to the blowpipe flame — on 
platinum wire, with or without a bead of borax or of micro- 
cosmic salt* (sodium, ammonium, and hydrogen phosphate, 
NaNH 4 HP0 4 ) ; on platinum-foil or in a porcelain crucible or 
on a crucible lid, with or without sodium carbonate ; or on 
charcoal, alone or in conjunction with sodium carbonate, potas- 
sium cyanide, or cobalt nitrate — will sometimes yield important 
information, especially to one who has devoted much attention 
to reactions producible by the blowpipe flame. The medical or 
pharmaceutical student, however, will seldom have time to 
work out this subject to an extent sufficient to make it a trust- 
worthy guide in analysis. (See Plattner and Muspratt, " On 
the Use of the Blowpipe," and a chapter in Galloway's " Man- 
ual of Qualitative Analysis.") 



Methods of Dissolving and Analyzing Single or Mixed Solid 
Substances. 

Having submitted the substance to preliminary examination, pro- 
ceed to dissolve and analyze by the following methods. These ope- 
rations consist in treating a well-powdered substance consecutively 
with cold or hot water, hydrochloric acid, nitric acid, nitro-hydro- 
chloric acid, or fusion with alkaline carbonates and solution of the 
product in water and acid. Resulting liquids are analyzed in the 
manner already described or by slightly modified processes, as detailed 
in the following paragraphs. 

Solution in Water. — Boil about a grain of the salt presented 
for analysis in about a third of a test-tubeful of water. If it 
dissolves, prepare a solution of about 20 or 30 grains in ^ an 
ounce or more of water, and proceed with the analysis in the 
usual way, testing first for the basylous radical or radicals by 
the proper group-reagents (HC1, H,S, NH 4 HS, (NH 4 ) 2 C0 3 , 
(NH 4 ) 2 HP0 4 ), pp. 224 or 258, and then for the acidulous rad- 



* So called because formerly obtained from the urine of man, who was 
called the microcosmos, or little world. 
17 



374 GENERAL QUALITATIVE ANALYSIS. 

ical or radicals, directly or by aid of the prescribed reagents 
(H,S0 4 , BaCl 2 , CaCl 2 , AgN0 3 , Fe 2 Cl 6 ), p. 369. 

If the salt is not wholly dissolved by the water, ascertain 
whether or not any has entered into solution by filtering, if 
necessary, and evaporating a drop or two of the clear liquid to 
dryness on platinum-foil ; the presence or absence of a residue 
gives the information sought. If anything is dissolved, pre- 
pare a sufficient quantity of solution for analysis and proceed 
as usual, reserving the insoluble portion of the mixture, after 
thoroughly exhausting with water, for subsequent treatment 
by acids. 

Solution in Hydrochloric Acid. — If the salt is insoluble in 
water, digest about a grain of it (or of the insoluble portion 
of a mixed salt) in a few drops of hydrochloric acid, adding 
water, and boiling if necessary. If the salt wholly dissolves, 
prepare a sufficient quantity of the liquid, noticing whether or 
not any effervescence (due to the presence of sulphides, sul- 
phites, carbonates, or cyanides) occurs, and proceed with the 
analysis as before, except that the first step, the addition of 
hydrochloric acid, may be omitted. 

The analysis of this solution will in most respects be simpler than 
that of an aqueous solution, inasmuch as the majority of salts (all 
those soluble in water) will be absent. This acid solution will, in 
short, only contain chlorides produced by the action of the hydro- 
chloric acid on sulphides, sulphites, carbonates, cyanides, oxides, and 
hydrates, and certain borates, oxalates, phosphates, tartrates, and 
citrates (possibly silicates and fluorides), which are insoluble in 
water, but soluble in acids without apparent decomposition. The 
first four — sulphides, sulphites, carbonates, and cyanides — will have 
revealed themselves by the occurrence of effervescence during solu- 
tion, and the presence of oxides and hydrates may often be inferred 
by the absence of compatible acidulous radicals. The borates, 
oxalates, phosphates, tartrates, and citrates alluded to will be repre- 
cipitated in the general analysis as soon as the acid of the solution 
is neutralized ; that is, will come down in their original state when 
ammonia and ammonium sulphydrate are added in the usual course. 
Of these precipitates, only the calcium oxalate and the calcium and 
magnesium phosphates need occupy attention now ; for barium 
oxalate and phosphate seldom or never occur, and the borates, tar- 
trates, and citrates met with in medicine or general analysis are 
all soluble in water. These phosphates and oxalates, then, will be 
precipitated in the course of analysis along with iron, their presence 
not interfering with the detection of any other metal. If from the 
unusually light color of the ferric precipitate phosphates and oxalates 
are suspected, it is treated according to the following table (refer- 
ence to which should be inserted in the table for metals, under Fe, 
p. 224, and in the long table opposite p. 258). 



METHODS OF EFFECTING SOLUTION. 



375 



Precipitate of Phosphates, Oxalates, Ferric Hydrate, etc. 

Dissolve in HCl, add citric acid, then NH 4 HO, and filter ; then 
follow the table below: 



Filtrate 

Fe. 

Add HCl and 

K 4 Fcy. 


Precipitate 
Ca 3 2P0 4 , CaC 2 4 , Mg 3 2P0 4 . 
Boil in acetic acid and filter. 


Blue ppt. 


Insoluble 
CaC 2 4 -* 

White. 
(CaF 2 may 
occur here.) 


Filtrate 

Ca 3 2P0 4 , Mg 3 2P0 4 . 

Add Am 2 C 2 4 , stir, filter. 




Precipitate 

white, indicating 

Ca 3 2P0 4 . 


Filtrate, 
add AmHO. 
White ppt. 
MgNH 4 P0 4 . 



In analyzing phosphates and oxalates advantage is also frequently 
taken of the facts that the phosphoric radical is wholly removed 
from solution of phosphates in acid by the addition of an alkaline 
acetate, ferric chloride, and subsequent ebullition, as described under 
"Phosphoric Acid" (p. 331), and that dry oxalates are converted 
into carbonates by heat, as mentioned under " Oxalic Acid " (p. 317). 
(See also p. 331, Fourth Analytical Reaction.) 

Certain arsenates and arsenites, insoluble in water but soluble in 
hydrochloric acid, may accompany the above phosphates and 
oxalates if from any cause hydrosulphuric acid gas has not been 
previously passed through the solution or passed for an insufficient 
length of time. 

If the substance insoluble in water does not ivholly dissolve 
in hydrochloric acid, ascertain if any has entered into solution 
by filtering,, if necessary, and evaporating a drop of the clear 
liquid to dryness on platinum-foil ; the presence or absence of 
a residue gives the information sought. If anything is dis- 
solved, prepare a sufficient quantity of solution for analysis, 
and proceed as usual, reserving the insoluble portion of the 
mixture, after thoroughly exhausting with hydrochloric acid 
and well washing with water, for the following treatment by 
nitric acid : 

Solution in Nitric Acid, — If the salt is insoluble in water and 
hydrochloric acid, boil it (or that part of it which is insoluble 

* Most oxalates, after being heated, effervesce on the addition of acid ; 
fluorides may be detected by the " etching " test. 



376 GENERAL QUALITATIVE ANALYSIS. 

in those menstrua) in a few drops of nitric acid. If it wholly 
dissolves, remove excess of acid by evaporation, dilute with 
water, and proceed with the analysis. 

This nitric solution can contain only a few substances, for nearly 
all salts soluble in nitric acid are also soluble in hydrochloric acid, 
and therefore will have been removed previously. Some of the 
metals, however (Ag, Cu, Hg, Pb, Bi), as well as amalgams and 
alloys, unaffected or scarcely affected by hydrochloric acid, are 
readily attacked and dissolved by nitric acid. Many of the sul- 
phides, also, insoluble in hydrochloric acid, are dissolved by nitric 
acid, usually with separation of sulphur. Calomel is converted, by 
long boiling with nitric acid, into mercuric chloride and nitrate. The 
nitrates here produced are soluble in water. 

This nitric solution, as well as the hydrochloric and aqueous solu- 
tions, should be examined separately. Apparently, time would be 
saved by mixing the three solutions together and making one 
analysis. But the object of the analyst is to separate every radical 
from every other ; and when this has been partially accomplished 
by solvents, it would be unwise to again mix and separate a second 
time. Moreover, solvents often do what the chemical reagents can- 
not — namely, separate salts from each other. This is important, 
inasmuch as the end to be attained in analysis is not only an 
enumeration of the radicals present, but a statement of the actual 
condition in which they are present : the analyst must, if possible, 
state of what salts a given mixture was originally formed — how the 
basylous and acidulous radicals were originally distributed. In 
attempting this much must be left to theoretical considerations, but 
a process by which the salts themselves are separated is of trust- 
worthy practical assistance ; hence the chief advantage of analyzing 
separately the solutions resulting from the action of water and acids 
On a solid substance. 

Solution in Nitro-liydrochloric Acid. — If the salt or any part 
of a mixture of salts is insoluble in water, hydrochloric acid, 
and nitric acid, digest it in nitro-hydrochloric acid, warming, or 
even boiling gently if necessary ; evaporate to remove excess 
of acid, dilute, and proceed as before. 

Mercury sulphide and substances only slowly attacked by hydro- 
chloric or nitric acid — as, for example, calomel and ignited ferric 
oxide — are sufficiently altered by the free chlorine of aqua regia to 
become soluble. 

Analysis of Insoluble Substances. 

If the substance is insoluble in water and acids, it is one or 
more of the following substances : Sand and certain silicates, 
such as pipeclay and other clays ; fluor-spar ; cryolite (3NaF,- 
A1F 3 ) ; barium, strontium, and possibly calcium sulphates ; tin- 
stone ; antimonic oxide ; glass ; felspar (double silicate of 



HYDRATES AND OXIDES. 377 

aluminium and other metals) ; silver chloride, bromide, or iodide ; 
lead sulphate. It may also be or contain carbon or carbona- 
ceous matter, in which case it is black and combustible, burn- 
ing entirely or partially away when heated in the air, or be or 
contain sulphur, in which case sulphurous gas is evolved, 
detected by its odor when the substance is heated in air. A 
drop of solution of ammonium sulphydrate, added to a little 
of the powder, will at once indicate the presence or absence of 
salts of such metals as lead and silver. For the other sub- 
stances proceed according to the following (Bloxam's) method : 

4 or 5 grains of the dry substance are intimately mixed with 
twice the quantity of dried sodium carbonate, and this mixture 
well rubbed in a mortar with five times its weight of deflagrat- 
ing flux (1 of finely-powdered charcoal to 6 of nitre). The 
resulting powder is placed in a thin porcelain dish or crucible 
or clean iron tray, and a lighted match applied to the centre of 
the heap. Deflagration ensues and decomposition of the vari- 
ous substances occurs, the acidulous radicals going to the alkali 
metals to form salts soluble in water, the basylous radicals 
being simultaneously converted into carbonates or oxides. 
The mass is boiled in water for a few minutes, the mixture 
filtered, and the residue well washed. The filtrate may then 
be examined for acidulous radicals and aluminium, and the 
residue be dissolved in diluted hydrochloric acid and analyzed 
by the ordinary method. 

The only substance which resists this treatment is chrome iron 
ore. 

To detect alkali in felspar, glass, or cryolite Bloxam recommends 
deflagration of the powdered mineral with 1 part of sulphur and 6 
of barium nitrate. The mass is boiled in water, the mixture filtered, 
ammonium hydrate and carbonate added to remove barium, the 
mixture again filtered, and the filtrate evaporated and examined for 
alkalies by the usual process. 

Hydrates and Oxides, 

If no acidulous radical can be detected in a substance under 
analytical examination, or if the amount found is obviously insuf- 
ficient to saturate the quantity of basylous radical present, the 
occurrence of oxides or hydrates, or both, may be suspected. Con- 
firmation of their presence will be found in the general rather than 
in any special behavior of the substances. Some hydrates yield 
water when heated in a dry test-tube held nearly horizontally in a 
flame, so that moisture may condense on the cool part of the tube. 
Some oxides yield oxygen, detected by heating in a test-tube and 
inserting the incandescent end of a strip of wood. Soluble hydrates 
cause abundant evolution of ammonia gas when heated with solu- 
tion of ammonium chloride. Soluble hydrates also give character- 



378 RECAPITULATORY AND OTHER NOTES. 

istic precipitates with the various metallic solutions. Hydrates and 
oxides insoluble in water not only neutralize much nitric acid or 
acetic acid, but are thereby converted into salts soluble in water. 
Most oxides and hydrates have a characteristic appearance. In 
short, some one or more properties of an oxide or a hydrate will 
generally betray its presence to the student who not only has know- 
ledge respecting chemical substances, but has cultivated the faculties 
of observation and perception. 

Fractional Operations. 

Not only is the common process of sifting (p. 372) through sieves 
of varying degrees of fineness a useful fractional operation or 
separatory adjunct in analytical as in other work, but also fractional 
elutriation (p. 134), fractional solution of a mixed mass by lixivia- 
tion (p. 89) of the substance with successive small quantities of 
solvents, and fractional precipitation with filtration after each addi- 
tion of successive small quantities of a precipitant. Fractional 
distillation {vide Index) is often very useful, fractional sublimation 
(p. 93) and fractional crystallization (p. 78) occasionally, fractional 
fusion less often. 



QUESTIONS AND EXERCISES. 



Describe the preliminary treatment to which a salt may be subjected 
prior to systematic analysis. — Mention substances which might be recog- 
nized by smell. — Which classes of salts are heavy, and which light? 
— Name some bodies detectable by their color. — What inference may be 
drawn from the appearance of steam when dry substances are heated ? — 
Why do certain crystals decrepitate ? — If a powder sublimes on being 
heated, to what classes of compounds may it belong? — When heat causes 
charring, what conclusion is drawn? — No change occurring by heat, 
which substances cannot be present ? — Give examples of salts which are 
identified by their reaction with strong sulphuric acid, and by their com- 
portment in the blowpipe flame, with or without borax or microcosmic 
salt. — What are the solvents usually employed in endeavoring to obtain 
a substance in a state of solution ? and what is the order of their applica- 
tion? — Name a few salts which may be present in an aqueous solution.— 
Mention some common compounds insoluble in water, but soluble in 
hydrochloric acid. — What substances are only attacked by nitric acid or 
nitro-hydrochloric acid ? — At what stage of analysis do arsenites and 
arsenates show themselves ? — Sketch out a method for the complete 
analysis of a liquid suspected to be an aqueous solution of neutral salts. 
— How can earthy phosphates and oxalates with ferric oxide be separated 
from each other? — How would you proceed to analyze an alloy? — By 
what process may substances insoluble in water or acids be analyzed ? — 
How would you qualitatively analyze glass? 



Recapitulatory and other Notes on the Constitution of the 
Definite Chemical Compounds commonly termed Salts. 

The molecules of a salt (p. 37) contain radicals (p. 67) which may 
be either elementary or compound (p. 67.) 



RECAPITULATORY AND OTHER NOTES. 379 

Each radical has a definite exchangeable value (p. 123). 

The definite exchangeable values of radicals differ in different 
series of radicals (pp. 123 to 125.) 

In one and the same molecule of a salt two or more different 
atoms of the same element may possess the two distinct functions of 
being — (a) a single definite distinct radical, and (b) one member of a 
group of atoms which together form a single definite distinct radical 
(pp. 124 and 264.) 

The relation to each other either of the elementary or the com- 
pound radicals in organic substances or salts is apparently far more 
complex than the relation to each other of the elementary or com- 
pound radicals in inorganic or mineral salts, as will be apparent when 
the section on Organic Chemistry has been studied. 

The properties of salts are regarded as depending on (a) the 
nature, (b) the number, and (c) the position in relation to each 
other, of the elementary and compound radicals in a molecule, as 
will be apparent when the subject of isomerism has been studied. 

Dumas, afterward Laurent, and then Gerhardt, attempted the 
classification of salts under such types as the following : 

h} h}o h}n 

The hydrogen type. The water type. The ammonia type. 

Other chemists have extended the number of such types of salts. 
Further, by writing the typical formulas in the above and other 
manners a mode of indicating the facts assumed to be dependent 
on the position of the atoms in a molecule has been sought to be 
obtained. Finally, the natural development of this train of thought 
and of practice has produced the graphic formulae of Kekule, Frank- 
land, and others, and has given rise to the doctrine of valency. 

Caution. — The conjectural or theoretic character of our ideas re- 
specting masses of matter being formed of molecules and molecules 
of atoms, and that molecules contain radicals consisting of one or 
more atoms, must never be lost sight of, highly valuable and prac- 
tically useful though the hypotheses be (see pages 36, 51-57, 139, 
264, 286, 299, 387.) 

Berthollefs Laws. — " When we cause two salts to react by means 
of a solvent, if, in the course of double decomposition, a new salt 
can be produced less soluble than those which we have mixed, this 
salt will be produced." " When we apply dry heat to two salts, if, 
by double decomposition, a new salt can be produced more volatile 
than the salts previously mixed, this salt will be produced." 

MalaguWs Law. — When solutions of two different salts are mixed 
and metathesis occurs, and four salts result, the proportions of the 
salts to each other are dependent on the strength or intensity of 
force with which the respective basylous and acidulous radicals are 
united. 

The state of equilibrium just mentioned may be permanent or 
temporary. The latter condition obtains when one of the salts 
which may possibly be produced is insoluble, for as soon as precipi- 



380 RECAPITULATORY AND OTHER NOTES. 

tation occurs the equilibrium is upset, and is re-established only to 
be upset again, and so on, until from the four salts there result one 
in solution and one out of solution. This would seem to be the way 
in which the laws termed " BertholletV work. 

The Periodic Law. — Observations by Newlands, elaborated by 
Mendelejeff and Lothar Meyer, point to a law thus expressed by the 
latter chemist : "If the elements are arranged in order of increasing 
atomic weights [by which the student will understand those actual 
combining weights conveniently termed atomic weights], the prop- 
erties of these elements vary from member to member of the series, 
but return more or less nearly to the same value at certain fixed 
points in the series." For example : 

Li Be B C N F Na Mg Al Si P S CI K Ca, etc. 

The periodicity of properties here alluded to occurs at about every 
eighth member of the series, irresistibly suggesting the periodicity 
of the musical scale. Thus sodium becomes the octave to lithium, 
silicon to carbon, phosphorus to nitrogen, sulphur to oxygen, chlo- 
rine to fluorine, potassium to sodium, calcium to magnesium, etc. 
Each chemical note (element) is distinct from the other, yet there is 
this curious harmony between any one and the eighth on either side. 
There are gaps in some of the series suggesting elements yet to be 
discovered, and irregularities suggesting the desirability of recon- 
sidering some of the present weights ; and other difficulties occur. 
Clearly the properties of the elements are in some way dependent 
on their "atomic" weights: the properties would indeed seem to be 
mere functions of these weights ; the properties would seem to be 
determined by the weights ; at all events, there is some such relation- 
ship between the elements, — all of which facts and considerations, 
by the way, irresistibly suggest the actual existence of atoms having 
fixed weight, and, pro tanto, very strongly support Dalton's atomic 
theory. Evidently there is less of fundamental difference between 
the so-called elements than we assume when we regard them as 
distinct elements. They would seem to be not so distinct as we 
commonly imagine. Whence the observed relationship of lithium, 
sodium, and potassium ; of nitrogen, phosphorus, arsenum, and 
antimony (pp. 166, 332) ; of oxygen, sulphur, selenium, and tellu- 
rium (p. 302) ; of carbon, silicon, and perhaps boron (p. 356) ; of 
chlorine, bromine, iodine (p. 278), and fluorine (p. 343)? Are the 
so-called elements one and the same matter, differing only in the 
weight of their ultimate particles ? Is the difference only, say, rate 
of vibration? They have not yet been transmuted. The subject is 
not developed sufficiently to warrant further consideration in this 
manual for ordinary medical and pharmaceutical students. Other 
students will find it fully considered in more advanced works. 
Papers and general statements will also be found in most journals 
of pharmacy. (See Pharmaceutical Journal, 3d Ser., vol. xviii. p. 
882.) 



ADVICE TO STUDENTS. 381 



ADVICE TO STUDENTS 

Respecting the Method of Studying the following pages on 
Organic Chemistry. 

Both medical and pharmaceutical students of organic chemistry 
may be divided into two classes — namely, junior students, or those 
who, in the first instance at all events, desire to obtain only a gen- 
eral acquaintance with the subject ; and senior students, or those who, 
having some general information, desire more complete and thorough 
knowledge of this branch of the science. To the members of each 
of these classes who use this Manual some advice concerning the 
kind and extent of work they may hope to accomplish in this depart- 
ment of the science will perhaps be acceptable. 

Junior Students. — The whole of the following section on organic 
chemistry should be read through carefully once or twice, with the 
object not so much of remembering all that is stated as of acquiring 
(a) a general view of the scope of the subject, (b) a clear notion of 
the modes of classifying organic substances, and (c) an intelligent 
perception of their broad relationships to one another, (d) Special 
attention should be given to the methods of preparing and testing 
the particular substances officially recognized in the British Phar- 
macopoeia, the student of practical chemistry preparing actual speci- 
mens of most of these substances, as well as going through tests for 
them and testing for impurities in them. He should make small 
quantities of chloroform, iodoform, spirit of nitrous ether, acetic 
ether, and a volatile oil ; should extract gum from a gum-resin ; 
purify some benzene, test aloin, and examine methylated spirit for 
its methylic constituent ; prepare some spirit of wine by fermenta- 
tion, concentrating the product until it will burn ; make ether ; con- 
vert amylic alcohol into valerianic acid ; test carbolic acid and 
glycerin ; manufacture a little soap ; extract mannite from manna ; 
go through the analytical reactions of cane- and grape-sugar ; obtain 
starch from wheat flour, maize flour, and a potato, and examine each 
product with the microscope ; make dextrin, pyroxylin, and collo- 
dion ; prepare and test aldehyde, and try the action of lime on 
chloral hydrate ; prepare and test acetic, oxalic, and citric acids ; 
emulsify sweet and bitter almonds : prepare elaterin and test jalap 
resin and salicin ; extract morphine or quinine or both, and perform 
the tests for the chief alkaloids of opium, cinchona, and nux vomica ; 
test albumen and pepsin. Having gone through these operations, 
he should again read through the whole section. 

Senior Students, having done all that junior students are, in the pre- 
vious paragraph, advised to do, should thoughtfully study every page, 
reading what one other author, at least, has to say on each subject. 
More especially they should actually prepare, or test, or otherwise 
experiment with, one or more typical members of most of the series 
or sub-series of organic bodies. For example, they should prepare 
the hydrocarbon methane (from sodium acetate), convert it into a 
haloid derivative (by one of the given methods), transform this into 
the alcohol (by the agency of silver oxide and water), and this again 
17* 



382 ADVICE TO STUDENTS. 

into the acid (by oxidation). The preparation of acetylene and 
ethylene and some of their derivatives should be tried ; the differ- 
ences between turpentine and petroleum spirit be experimentally 
proved ; nitro-benzene be made, this be converted into aniline, and 
this again into "mauve-," aloin should be prepared; methylic 
alcohol be extracted from crude wood spirit and absolute alcohol be 
obtained from spirit of wine ; alcohol and acetic acid be regenerated 
from the acetic ether previously prepared (by ebullition with a 
strong aqueous solution of potash) ; ethyl iodide or bromide and 
perhaps zinc-ethyl be made •, glycol be prepared, and then be oxi- 
dized 5 glycerin be examined ; starch be converted into dextrin and 
into sugar 5 malt extract be examined for diastase 5 trinitrocellulin 
be made ; acetic aldehyde be fully examined and aldehyde-ammonia 
be prepared ; lactic acid be made ; benzoic and salicylic acids and 
aldehydes be obtained ; natural urea be extracted and artificial urea 
be made ; the glucosides be examined ; and one or two artificial 
alkaloids be prepared ; etc. Melting-points and boiling points of 
pure substances should be taken 5 and fractional distillation should 
be applied, either to acetic acid with a view to separate glacial acid 
on the one hand from water or weak aqueous acid on the other, to 
mixed alcohol and water with the object of attempting their re-sepa- 
ration as far as possible, or to some such mixture. Especially must 
the operations of quantitative analysis of organic compounds in due 
time be fully and thoroughly performed. 

Other Students. — Students who have no occasion to apportion 
their periods of study in the manner contemplated in the previous 
paragraphs are recommended to go through the succeeding sections 
as they have gone through the foregoing — namely, page by page. 

Note. — Students will find that in working at organic chemistry, 
so called, they are not departing from the method of study hitherto 
pursued. Hitherto they have concentrated attention on the chief 
elements, one at a time ; they are now about to investigate the com- 
pounds of another of those elements ; that is all. But it is an ele- 
ment having a greater range of combining powers than any yet 
examined. Organic chemistry is the chemistry of the element 
carbon. 



ORGANIC CHEMISTRY;* 



THE CHEMISTRY OF CARBON COMPOUNDS. 



Introduction. 



Except alcohol and a few acids, the large number of compounds 
which have hitherto engaged notice in this Manual have been of 
mineral origin. But the two other kingdoms of nature, the animal 
and vegetable, furnish still larger numbers of definite substances. 
These latter compounds, indeed, when discovered, were producible 
only by organized living structures ; hence were termed, more than 
two hundred years ago, organic (from bpyavov, organon, an organ), 
and their study was termed organic chemistry. A very large num- 
ber of organic compounds can now, however, be obtained artificially 
— without the aid of a living organism ; hence the particular dis- 
tinction formerly drawn between organic and inorganic compounds, 
"organic" and "inorganic" chemistry, no longer fully obtains. 
Another definition, or additional definition, of organic chemistry or 
the chemistry of animate nature, the laws of which do not differ 
from those of inanimate nature, is now generally adopted — namely, 
the chemistry of carbon compounds. No doubt two or three kinds 
of compounds of carbon — carbonic acid gas and carbonates, for 
example — are met with in the mineral kingdom, and are therefore 
inorganic compounds, but they are met with in the organic kingdoms 
too, and therefore are organic compounds also. 

Practically, all carbon compounds are organic compounds, and 
all of the so-called organic compounds are carbon compounds ; hence 
the old term, organic chemistry, no longer being etymologically and 
fully applicable, that of the chemistry of the carbon compounds seems 
natural as well as useful. Moreover, the carbon atoms possess in 
an altogether exceptional degree a property either not possessed or 
only to a much slighter extent possessed by those of other elements 
— namely, the property of combining with one another, and forming 
a sort of chain, to every link of which atoms of other elements can 
be attached, the result being obviously molecules of almost infinite 
variety and complexity — a fact which alone suffices to secure for 
carbon special and separate consideration by chemists. In short, 
the chemistry of the carbon compounds includes what was formerly 
as well as what is now known as organic chemistry ; or, in other 
words, the chemistry of organized or animate nature is included in 

* Eead the two previous pages of Advice to Students. 

383 



384 ORGANIC CHEMISTRY. 

the chemistry of the carbon compounds. Of course, so old and his- 
torically interesting a term as organic chemistry will continue to be 
used ; and there is no objection to such use, provided students 
remember that when the term is used as the equivalent of the chem- 
istry of the carbon compounds, it is only conventionally and not ety- 
mologically accurate. Moreover, the chemistry of a carbon com- 
pound includes the chemistry of every element in that compound 
and the chemistry of the compound as a whole — facts which obtain 
even more prominence if the chemistry be spoken of by a general 
word, such as organic, rather than by the specific word carbon. 
Indeed, those organic compounds which contain nitrogen seem to 
be conditioned as much by their nitrogen as their carbon. So that, 
the word organic having now in chemistry lost its original specific 
signification, and having acquired the general signification described, 
it becomes, by its associations, perhaps the best word that can be 
chosen as the title of the great division of chemistry now under 
consideration. 

Composition of Organic Compounds. 

(a) Qualitative Composition. — The presence of carbon in a com- 
pound is at once shown if the compound blackens when a little is 
heated on a knife or platinum-foil in a flame. If the substance is 
heated in a dry, narrow test-tube and much moisture is condensed 
on the upper cool part of the tube, the presence of hydrogen and 
oxygen is reasonably inferred. Nitrogen may be detected by the 
odor of ammonia emitted on strongly heating the substance with a 
dry mixture of soda and lime, or it may be sought by carefully but 
strongly heating in a test-tube a small portion of the substance with 
a very small piece of sodium, and, after all action ceases, digesting 
the residue in water, filtering, and adding to the filtrate a ferrous 
salt, a ferric salt, and hydrochloric acid ; a precipitate of prussian 
blue indicates nitrogen. Chlorine, bromine, iodine, sulphur, and 
phosphorus may be detected by heating the substance with nitric 
acid and silver nitrate in a very carefully and strongly sealed tube 
(in a fume-chamber, with such precautions that if the tube burst 
no harm to the operator shall ensue), and testing the product for 
chlorides, bromides, iodides, sulphates, and phosphates by methods 
already described. 

(b) Quantitative Composition. — The qualitative composition of an 
organic substance being ascertained, the quantities of each element 
are then determined by methods which the student will practise 
when he is sufficiently advanced to work at the sections on quanti- 
tative analysis. The principles of the methods, are, however, 
simple, and may at once be described. For the quantitative estima- 
tion of carbon and hydrogen a carefully weighed portion of the sub- 
stance is completely burned ; the products, which are, of course, car- 
bonic acid gas and water, are collected and accurately weighed. Of 
every 44 parts of the carbonic acid gas (C0 2 = 44), 12 will be car- 
bon, and of every 18 parts of the water (H 2 = 18), 2 will be hydro- 
gen ; in other words, three-elevenths of the weight of carbonic acid 



COMPOSITION OF COMPOUNDS. 385 

gas obtained will be the carbon of the original substance, while one- 
ninth of the water obtained will be the hydrogen of the original 
substance. If nitrogen be present, another weighed portion of the 
substance is so burned as to yield all its nitrogen as gas, which is 
carefully collected and measured, or it is heated with a mixture of 
soda and lime, when the nitrogen takes up hydrogen and becomes 
ammonia, which is collected and accurately estimated ; of every 17 
parts of ammonia (NH 3 = 17), 14 will be nitrogen. The amounts 
of chlorine, sulphur, etc., elements not often present, are obtained 
by subjecting carefully weighed portions of the original substance 
to the nitric treatment already alluded to, collecting and weighing 
the products, and calculating what proportions of the products are 
chlorine, sulphur, etc. The amount of oxygen is ascertained by 
difference ; that is to say, the difference between the sum of the 
weights of carbon, hydrogen, nitrogen, etc. and the original weight 
of substance will be the weight of the oxygen in that original weight 
of substance. 

For example, a fluid having well-marked definite properties, and 
known to contain only carbon, hydrogen, and oxygen, is so burned 
that 0.3 of a gramme* of it yields 0.5738 of a gramme of carbonic 
acid gas, and 0.3521 of water. As three-elevenths of the carbonic 
acid gas is carbon, and one-ninth of the water is hydrogen, it follows 
that the 0.3 of substance contains 0.1565 of carbon and 0.0391 of 
hydrogen ; and the difference between these two figures and 0.3 
being 0.1044, it follows that 0.1044 is the amount of oxygen in the 
0.3 of original substance. For, 0.5738 X 3 -f- 11 =0.1565 ; and 
0.3521 ~ 9 s 0.0391 ; 0.3 — (0.1565 + 0.0391) = 0.1044. 

(c) Centesimal Composition. — It is usual to make at least two 
such analyses of any organic compound •, and, as different weights 
of the original substance will almost necessarily be subjected to 
combustion (for it is easier to counterpoise by weights a selected 
quantity than it is to counterpoise with the substance any selected 
weights), the results of the combustion can best be compared by 
converting the numbers first obtained into percentages 5 that is to 
say, by assuming in, for instance, the present case, that not 0.3 
parts of substance were operated on, but 100 parts. This is one of 
the simplest of arithmetical operations. If 0.3 of substance yields 
0.1565 of carbon, 100 of substance will yield 52.17 of carbon. If 
0.3 of substance yields 0.0391 of hydrogen, 100 of substance will 
yield 13.03 of hydrogen. And if 0.3 of substance yields 0.1044 of 
oxygen, 100 of substance will yield 34.80 of oxygen. 

(d) Chemically Empirical Composition. — But the chemist further 
desires to know, not so much what percentages or ordinary unit- 
weights of elements are contained in the compound, but what rela- 
tive number of chemical unit-weights or atomic weights are present 
— how many parts of carbon each weighing twelve, how many parts 
of hydrogen each weighing one, how many parts of oxygen each 

- * If the reader is not already familiar with the metric system of 
weights and measures, he is referred to the section on that subject in the 
latter part of the Manual. {Vide Index, " Metric System.") 



386 ORGANIC CHEMISTRY. 

weighing sixteen, how many parts of nitrogen each weighing four- 
teen, etc. This too is one of the simplest of arithmetical operations. 
Divide the percentage of carbon by 12, of hydrogen by 1, of oxygen 
by 16, of nitrogen by 14, etc. Thus, in the present case, 52.17 -r- 
12 = 4.347 atomic weights of carbon; 13.03 -f- 1 = 13.03 atomic 
weights of hydrogen; and 34.80 -f- 16 = 2.171 atomic weights of 
oxygen. Reducing these three fractional numbers of atomic weights 
to the lowest whole numbers (by assuming that the lowest of the 
three will represent 1 atomic weight — that is, by dividing the two 
higher of the three by the lowest), we find that the compound is 
composed of 2 atomic weights of carbon, 6 of hydrogen, and 1 of 
oxygen, thus : 4.347 — 2.171 = 2 of carbon ; 13.03 ~ 2.171 = 6 of 
hydrogen ; 2.171 ~ 2.171 = 1 of oxygen. The result is that of pro- 
portions of carbon each weighing 12, the substance contains 2 ; of 
proportions of hydrogen each weighing 1, the compound contains 6 ; 
and of proportions of oxygen each weighing 16, the compound con- 
tains 1. Finally, instead of the words " proportion of carbon weigh- 
ing 12," the simple capital letter C may be used, which, as the 
reader now well knows, is not only the shorthand or symbol for the 
word carbon, but stands for 12 parts of carbon. Similarly, H may 
stand for 1 part of hydrogen, and for 16 parts of oxygen ; whence 
we arrive at C 2 H 6 as the simplest chemically empirical expression, 
or empirical formula, of the substance under consideration. 

(e) Chemically Rational Composition. — From the empirical form- 
ula of a substance we pass to a two-volume formula ; that is to say, 
in accordance with the practice of chemists, the formula must, if 
possible, represent two volumes of the substance when in the state 
of vapor (see pp, 55 and 58). 2 parts of hydrogen gas, or 17 of 
ammonia gas, or 18 similar parts of water vapor, or 44 of carbonic acid 
gas, or 36| parts of hydrochloric acid gas, etc. occupy, if all are at 
the same temperature and under the same pressure, the same 
volume ; whence we derive the formulae H 2 , NH 3 , H 2 0, HC1, and C0 2 
as formulas comparable with each other. If, now, the vessel which 
held these quantities of the respective substances be filled with the 
vapor of the substance supposed to be under examination at the 
same temperature and pressure, and the vessel and contents be 
weighed, the contents will be found to weigh 46 similar parts. C 2 H 6 
will be found, on adding up the atomic weights, to represent 46 
parts by weight. Therefore C 2 H 6 is the two-volume formula as 
well as the empirical formula, and thus the first step has been taken 
from the formula chiefly obtained by chemical art, an empirical for- 
mula, toward one largely obtained by, and that satisfies, the reason — 
a rational formula or structural or constitutional formula. Had the 
weight been found to be 92, the two-volume formula would have 
been C 4 H 12 2 . The actual method of taking these weights of equal 
volumes of gases and vapors (specific gravity and vapor-density) 
will be described in the paragraphs on quantitative analysis. 

(f) Molecular Composition. — Equal volumes of gases and vapors, 
being similarly affected by temperature and pressure, must be 
similarly constituted (Avogadro and Ampere's conclusion, pages 53 
and 54). Whatever .the number of molecules in such equal volumes 



CONSTITUTION OF COMPOUNDS. 387 

may be, it must be the same in each. Therefore the weights of 
equal bulks of gases and vapors under like conditions represent the 
relative weights of the respective molecules. Hence 2, 17, 18, 44, 
and 36.5 respectively represent the weight of one molecule of each 
of the substances hydrogen, ammonia gas, water vapor, carbonic 
acid gas, and hydrochloric acid gas, and 46 represents the molecular 
weight of the substance under consideration. C 2 H 6 therefore 
represents the composition of a molecule of the substance. C 2 H 6 
is the molecular formula of the substance. (The substance is com- 
mon alcohol.) 

Acetic acid will serve as another simple illustration. Analysis 
and arithmetic yield the formula CH 2 0. But metals only displace 
one-fourth of the hydrogen in any given weight of acetic acid. That 
fact cannot be shown by the formula CH 2 0, but it can by the doubled 
formula C 2 H 4 2 . This chemical evidence that the latter formula is, 
so far, correct is supported by the physical evidence of vapor-density 
as interpreted in the previous paragraph. (See also " Vapor-density " 
and "Raoult's Experiments" in Index.) 

Check on Composition. — If the formula found is, even so far, the 
true formula of the substance, the centesimal composition found by 
experiment ought to be practically the same— the same within the 
limits of experimental error — as the centesimal composition obtained 
by calculation from the formula, thus : 

Calculated. Found. 

C 2 = 24 52.174 52.170 

H 6 = 6 13.043 13.030 

= 16 34.783 34.800 



46 100.000 100.000 



From composition we now pass to constitution. What we know 
of the composition of a substance is reflected in its empirical for- 
mula. A step in advance is recorded in the molecular formula. 
What is afterward learnt about constitution is exhibited in the struc- 
tural formula. If the letters in a formula — for instance, C 2 H 6 — 
be regarded only as representing fixed weights, the formula ex- 
presses only facts ; but we also regard the letters as representing 
atoms (Dalton's theory), and the whole formula as representing a 
molecule (Avogadro's theory), while in attempting structural for- 
mulas we further depend on the idea of the valency of atoms. To 
this subject of structure or constitution we now pass. 



Constitution of Organic Compounds. 

In the molecule of an organic compound how are the atoms 
arranged ? This is perhaps the greatest problem the chemist has 
to solve. Like the toy-puzzles of our youth, these chemical puzzles 
have to be attacked analytically and synthetically. How to sepa- 



388 ORGANIC CHEMISTRY. 

rate into its constituent bars of wood that apparently solid cube 
given to us by a friend in old days was not an uncongenial task, 
but, once accomplished, how to put these bars together again was a 
still more fascinating if more difficult labor. How to separate the 
groups of atoms or radicals in molecules of chemical substances, or 
at least how to find out the positions of those groups in a molecule, 
is a most difficult yet fascinating task for the skilled enthusiast in 
chemistry 5 and how to so marshal those groups (drawn perhaps 
from several different sources, and visible and tangible only in a 
state of combination and in mass) that he shall produce by art the 
compound originally only furnished by nature, is still more difficult, 
but also more fascinating — more fascinating, firstly, because it will 
furnish proof that his synthetical work was sound ; secondly, be- 
cause by artificially and perhaps cheaply producing a rare color, a 
rare perfume, a rare flavor, or a previously costly medicine, he may 
become a benefactor to his fellow-man ; and, thirdly, because he 
may gain the honor of unveiling for all time one more of the truths 
of nature. 

In practically attacking the problem of the constitution of a com- 
pound the chemist proceeds to note whether the substance is acid, 
alkaline, or neutral 5 to act on it with a base of known constitution 
if it is an acid, or with an acid of known constitution if it is a base, 
and to analyze the produced salts ; to oxidize it 5 to deoxidize it ; to 
chlorinize it 5 to remove or add hydroxyl (HO), carbonyl (CO), etc. ; 
to substitute hydrogen by a compound radical, and vice versa; to 
heat it 5 to electrolyze it ; and, generally, to perform many such 
operations in the hope that the lines of chemical cleavage in the 
molecule will be detected, the essential groupings of atoms in 
the molecule be discovered, and even the positions of atoms or 
groups of atoms in relation to each other be reasonably inferred. 
Briefly, similarity in properties implies similarity in constitution or 
structure. Per contra, similarity in structure being reasonably 
implied, reference to properties shows whether or not the reason 
is on the right track toward truth in the matter of constitution or 
structure, the advance toward error being prevented and toward 
truth being maintained, whatever be the result of the reference, 
new truths not infrequently being unveiled. Thus, by the way in 
chemistry do fact and theory ever discharge their obligations to 
each other. 

For example, urea, which was the first organic body produced 
artificially, was obtained by Wohler in 1828 on heating solution 
of ammonium cyanate; H 4 NCNO became OC(NH 2 ) 2 , the mere 
change in the position of the constituent atoms — that is, in the 
structure of the molecules (indicated roughly, but to the best of 
our judgment, by the change in the relative position of the letters 
in the two formulae just given) — accounting for the differences in 
the properties of the two substances, just as the differences in the 
relative position of a given number of stone blocks which at first 
were put together to form a bridge, but afterward were put together 
to form a house — that is, the differences in the structure of the 
edifices — account for the differences in their properties. 



NOTATION OF COMPOUNDS. 389 

Notation of Organic Compounds. 

In order that we may convey to one another our conclusions 
respecting the constitution of organic compounds, notation has to 
be carried somewhat farther in organic than has already been 
shown to be necessary in inorganic chemistry (see pp. 42 and 46). 
The relative position of atoms and groups of atoms in a molecule 
may be indicated by placing the symbolic letters above or beneath 
one another as well as on one line, and the quantivalence of atoms, 
as well as the directions in which we conclude they are joined in 
the molecule, may be indicated by lines ( — = or =) or dots 
(•:•), either completely or only partially employed throughout 
the formula; each dot, and especially each line or "bond" or 
" link," representing such union between two neighboring atoms 
or radicals as would be represented by the extended arms of two 
persons shaking hands. For instance, the statement just made that 
ammonium cyanate (H 4 NCNO) becomes urea [empirically CH 4 N 2 0, 
or rationally OC(NH 2 ) 2 ] might be represented by either of the 
following forms of equation : 

H 4 =N-C=N=0 becomes 0=C< || 

\N=H 2 

N :H 2 
H 4 ! N • C • N : becomes : C : •• 

N:H 2 

Here, bars in the first equation and dots in the second show not 
only the quantivalence, but especially the distribution, of the chem- 
ical affinity expressed by the quantivalence of each atom. Thus 
the first four bars or dots not only indicate the univalence of each 
of the four hydrogen atoms on the one hand, and four-fifths of the 
quantivalence of the first nitrogen atom on the other hand, the next 
bar or dot showing the remaining fifth, but the five bars or dots 
also indicate that of the total affinity of the nitrogen atom four- 
fifths are engaged with a corresponding amount of attraction 
offered by four univalent hydrogen atoms, while the other fifth 
is engaged with one-fourth of the total attraction of the adjacent 
carbon atom. And so on with the quadrivalence of the carbon 
atom, the quinquivalence of the second nitrogen atom, and the 
bi valence of the oxygen atom. 

But it is unnecessary, indeed undesirable, thus to indicate the 
quantivalence of each atom in a molecule, the closeness of union 
of groups of atoms (radicals) within a molecule being best indi- 
cated by putting the symbolic letters in a formula as close together 
as written characters or printer's types will allow ; moreover, an 
atom, such as nitrogen, may often pass from one degree of activity 
to another during a reaction. The following, therefore, are better 
arrangements ; 

H 4 N-CNO becomes 0=C<^J 2 
H 2 N • CNO becomes : C : (NH 2 ) 2 . 



390 ORGANIC CHEMISTRY. 

Indeed, after a time the chemical student will find that his own 
imagination will often best supply that which is intended to be 
indicated by the lines or dots in the formulas of organic compounds, 
actual lines or dots only being employed where their use tends to 
promote clearness in a formula. For printed lines look like bars, 
and these, and even dots, are liable to suggest separation, whereas 
in a chemical formula they should suggest the union of the atoms 
and radicals in the molecule of which the formula is the crude 
picture. While suggesting links and bonds, however, and the 
affinity (quantivalence or valency) of the atoms, they must be re- 
garded as indicating line of force rather than anything more sub- 
stantial. Again, symbols and formulas, written or printed, are 
necessarily exhibited on surfaces, whereas the conception of a 
molecule should be that of a sphere — that of grapes on a bunch 
of apples on a tree, rather than balls on a billiard-table ; or, still 
better, that of moons round a planet and planets round a sun, all 
kept in their places by force rather than by anything material ; our 
conceptions should be stereochemical, should be stereoscopic pictures 
rather than pictures of objects on a plane surface without perspect- 
ive. (See also p. 393.) 

Finally, bars, dots, or what not must only be placed in a formula 
where actual experiment warrants, unless the statement is distinctly 
made or understood that the suggested formula is only hypothetical. 
The use of such apparently highly complicated graphic rational 
formulae or constitutional or structural formulae — as, for example, 
the following formula for uric acid — is fully justified by a series of 
well-defined experiments : 

HN— CO 

I I 
CO C— NH 

II. / C ° 
HN— C-NH 

Here not only is the univalence of each of the hydrogen atoms, 
the bivalence of oxygen atoms, the trivalent character of each of 
the nitrogen atoms, and the quadrivalent nature of each carbon 
atom shown, either directly by bars attached to the symbols or 
suggestively by the position of a symbol of recognized quantivalence 
next to another symbol of recognized quantivalence, but the positions 
which experiment warrants us in believing that the radicals occupy 
within the molecule are indicated in the formula by the position of 
the symbols for those radicals (HN, imidogen ; CO, carbonyl) near 
central atoms of carbon. 

To the student the great advantage of extended formulae, whether 
ordinary or graphic, consists in the relationships which they clearly 
exhibit between compounds which otherwise are not readily shown 
to be related to one another. The constitution or structure, so far 
as can at present be inferred, of chemical compounds of interest to 
the medical or pharmaceutical student will be found to be given, 



HYDROCARBONS. 391 

when desirable, in this Manual. Students who desire to pursue the 
subject more fully must seek other guides. 

The structural formulae characteristic of modern chemistry may 
be regarded as pictures of our idea of architecture in nature's mole- 
cules. The first sketches are seen in such formulae as HC 2 H 3 2 . 
Among the earlier mid-century artists were Gerhardt, Williamson, 
Frankland, and, especially from 1858 onward, Kekule. 

Caution. — Our conception of the structure or constitution of 
masses or moles of matter, or of particles or molecules, or of the 
atoms of which we conceive molecules are composed, or of the 
valency of those atoms, are nothing more than conceptions. All 
varieties of chemical formulae are but concrete reflections or pictures 
of those conceptions. Why do we make those conceptions, and why 
do we thus picture those conceptions? We make them because, 
firstly, the enormous number of facts that chemistry unfolds creates, 
in the healthy human mind, a demand for classification ; and, sec- 
ondly, because the healthy human mind instinctively demands the 
reason why facts are as they are. And why do we adopt the existing 
chemical formulae as concrete reflections of our abstract ideas ? Be- 
cause, firstly, intercommunication between minds can only be 
accomplished satisfactorily either by human utterances or by those 
written or printed equivalents, or signs, or symbols of speech termed 
letters, etc. (singly or combined to form words, etc.) ; and, secondly, 
because, as regards any one mind, the desire to avoid utter mental 
confusion demands the adoption of some method of concretely 
ticketing and labelling our ideas, so that we can set them aside or 
take them up at a moment's notice ; and no better method than that 
offered by letters and similar signs has yet been devised, whether for 
the concrete expression of one's own thoughts for one's self or for 
written or printed intercommunication between mind and mind. In 
chemistry, however, we take care to use formulae, letters, or symbols, 
(dots, bars, brackets, or what not) only to represent our conceptions 
respecting facts, except when we designedly, openly, and temporarily 
use them as a mode of giving rein to the imagination, hoping thereby 
to be led to inferences which experiments shall prove to be facts. 



From the consideration of the composition and constitution of 
organic compounds we now pass to the subject of classification. 



HYDROCARBONS : NEUTRAL OR NORMAL, AND 
BASYLOUS. 

Neutral or Normal Hydrocarbons. — The simplest compounds of 
carbon are those with hydrogen ; and as the atom of carbon is quad- 
rivalent and the atom of hydrogen univalent, it follows that if a 
single atom of carbon be fully saturated with hydrogen, the formula 
of the resulting molecule must be CH 4 . But carbon is of all elements 
that which is peculiarly and specially liable to unite with itself (as 



392 ORGANIC CHEMISTRY. 

magnets attract each other), so far, at all events, as a portion of the 
attractive power of its atom is concerned, the other portions of its 
power attracting and being attracted by other atoms, the result 
being, possibly, molecules of great complexity. The following 
graphic formulae will illustrate this point: 



H HH HHH HHHH 

I II III I I I I 

H— C— H H— C— C— H H— C— C— C— H H— C— C— C— C— H 

I II III I I I I 
H HH HHH HHHH 



These formulae represent well-known hydrocarbons, the first being 
common marsh-gas, or methane, one molecule of which is otherwise 
represented by the shorter formula, CH 4 ; the next represents ethane, 
C 2 H 6 ; the third propane, C 3 H 8 ; while C 4 H 10 is the formula of butane 
or tetrane. The first three members of the series are gases ; those 
which immediately follow are liquids, C 5 H ]2 , C 6 H 14 , etc. ; while the 
highest members are solids, several of which form the mixture of 
hydrocarbons known as common paraffin ; indeed, the whole series 
are distinguished as the paraffin series of hydrocarbons. It will be 
observed that the four units of affinity of the carbon atom are, in the 
molecule of each substance, fully saturated either by the affinities of 
adjacent hydrogen atoms or by that of another carbon atom. The 
substances are illustrations of saturated hydrocarbons (neutral or 
normal hydrocarbons). They differ in composition by CH 2 : add 
CH 2 to the first, and you obtain the second ; add CH 2 to the second, 
and you obtain the third 5 and so on. The members of this series 
resemble each other in containing, to a given number of carbon 
atoms, twice that number, with two added, of hydrogen atoms. 
Representing "any number" by the letter n, the general formula 
for members of this neutral series of hydrocarbons will be C u H 2 a + 2. 
Like neutral inorganic salts, their elements have saturated each 
other's affinities ; hence the molecules refuse further to unite by 
direct or indirect addition with atoms having attractive powers. 
Potassium is powerfully basylous, chlorine powerfully acidulous — 
each has great affinity for the other ; but the product, potassium 
chloride, KC1, is comparatively neutral or normal ; saturated hydro- 
carbons are in the same case, for they do not unite with any other 
substances. 

Basylous Hydrocarbons. — Many hydrocarbon groups, such as 
"methyl," CH 3 , and "ethyl," C 2 H 5 , apparently have strong basyl- 
ous affinities, because in compounds they appear to play the part 
which in inorganic compounds is performed by those basylous 
metals, etc. (K, Fe, NH 4 , e. g.) which are commonly called inorganic 
radicals. Indeed, such hydrocarbon groups are often termed 
organic radicals, and to hold the theory that they exist is convenient ; 
but any attempt to isolate them results in the production of neutral 
hydrocarbons, C 2 H 6 , C 4 H 10 , etc. 

Some hydrocarbons, however, which can quite easily be isolated, 
are basylous, such as ethylene, C 2 H 4 , and other bivalent radicals 



HYDROCARBONS. 



393 



having the general formula C n H 2n ; and acetylene, C 2 H 2 , and other 
quadrivalent radicals having the general formula C n H 2n -2. Such 
radicals are sometimes termed unsaturated hydrocarbons : 



1 

H— C— H 

1 

H 
Methyl? 


H— C— C— H 

Ah 

Ethylene ? 


i i 

H— C— C— H 

1 1 

Acetylene ? 


their compounds with, 


for example, bromine, being thus formulated : 


Br 


Br Br 

I 1 


Br Br 

i i 


H— C— H 

h 


H— C— C— H 

i i 


1 1 
H— C— C— H 


h I 


1 1 
Br Br 



But the first is probably methane, in which one atom of hydrogen 
is substituted by one of bromine, other salts containing the supposed 
non-isolable radicals being normal hydrocarbons in which atoms of 
hydrogen are substituted by atoms of acidulous elements or acidu- 
lous radicals, the residual hydrocarbon being the so-called basylous 
radical. And as regards the basylous hydrocarbons which can be 
isolated, they too probably are neutral hydrocarbons in which the 
carbon atoms are united to the extent of half or even three-fourths 
of their affinities, thus : 



H— C=C— H 

u 

Ethylene. 



H— CeeC— H 

Acetylene. 



Bring bromine into contact with these so-called free basylous radi- 
cals, and in the case of ethylene one pair of carbon "arms" maybe 
considered to unclasp, each of the two free arms clasping a one- 
armed bromine atom ; while, in the case of acetylene first one pair 
of arms unclasp and take in two bromine individuals, and then 
another pair unclasp and take in two more individuals of a bromine 
molecule. 

Br Br 



Br— Br 



Bromine. 



H— C=C— H 

Acetylene. 



H— C=C— H 

Br Br 

Acetylene 
dibromide, or 



H— C— C-H 

I I 
Br Br 

Acetylene tetrabromide, 
or dibrom-ethylene 



dibrom-ethylene. bromide, or tetrabrom- 
ethane. 



Molecules. — Instead of the foregoing plane-conceptions of molecules, 
stereo-conceptions have been suggested (see p. 390). Thus a tetra- 
hedron may represent a carbon atom, or the area of influence of the 



394 ORGANIC CHEMISTRY. 

(central) carbon atom, its corners or summits representing the foci 
of its affinities or valencies — foci at which atoms of hydrogen or of 
compound radicals will find place or in the vicinity of which they 
will oscillate. Two or more of such tetrahedra may be regarded as 
united by their corners, edges, or faces according to circumstances. 
This subject cannot be pursued here. Chemists seem to be gliding 
from statical notions of chemical structure to dynamical ideas, slowly 
discarding the principle of affinities between fixed particles for that 
of atoms conditioned by motion. (See the memoirs of Van't Hoff, 
Lebel, Mayer, Guye, and others.) 

Series of Hydrocarbons. — Three distinct series of hydrocarbons 
have now incidentally been alluded to — namely, the paraffin series, 
C n H 2n +2 ; the olefine series, C n H 2n ; and the acetylene series, C n H 2a _ 2 . 
Twelve or fourteen other series are known, as, the terpene series, 
C n H 2n -4 ; the benzene series, C n H 2a _ 6 ; the cinnamene series, 
C u H 2n _ 8 ; the anthracene series, C n H 2n _i 8 , etc. Each member -of 
any such series obviously differs in composition from the preceding 
or succeeding member by CH 2 . Either series will therefore be an 
illustration of an homologous series (from bfibg, homos, the same, and 
Tidyog logos, proportion) of compounds. There will be similar 
homology, of course, between the members of the series of alcohols 
derived from these hydrocarbons, or between the haloid salts, the 
ethers, the aldehydes, the acids, etc. Homology is necessarily con- 
current with step-by-step variation in the properties of members of 
a series. 

Substitution. — The atoms of hydrogen in any member of either 
of the series of hydrocarbons may be substituted by radicals of all 
kinds — basylous and acidulous, elementary and compound ; by chlo- 
rine or bromine, hydroxyl or sulphydroxyl, oxygen or sulphur, 
amidogen or imidogen, carboxyl, etc. Very large numbers of 
organic compounds have thus been obtained artificially ; still larger 
numbers have been proved, analytically, to have distinct existence ; 
while it is certain that still larger numbers exist of which we do 
not know the constitution and only partially know the composition. 

Note. — The idea of substitution, in chemistry, involves or includes 
the conception of the unity of a molecule as opposed to the old-fash- 
ioned conception of duality ; involves the unitary conception under 
which we picture a molecule of, say, anhydrous Epsom salt as 
MgS0 4 rather than MgO,S0 3 ; or, figuratively, involves that concep- 
tion of oneness or wholeness in a building which allows of one kind 
of brick being substituted by another kind without change in the 
structure qua structure. That the idea of substitution also involves, 
in chemistry, a somewhat unwieldy notation and an extremely 
unwieldy nomenclature appears at present to be inevitable. 

Procedure as regards Further Study. 

Several of these series of hydrocarbons and their substitutional 
derivatives will now be described, special notice being given to 
the compounds of medical and pharmaceutical interest. Some 
members of the paraffin, olefine, acetylene, terpene, benzene, 



HYDROCARBONS. 395 

naphthalene, and anthracene series will be treated of, together with 
their haloid, nitrous, and acetic derivatives, etc ; the alcohols or 
hydroxyl substitution-compounds will then be noticed as a class •, 
and afterward the carbohydrates, amyloids, aldehydes, acids, glu- 
cosides, and alkaloids. 

The series of chief interest to medical and pharmaceutical and — 
indeed, to all — students is the first, known by either of the four 
names Paraffin, Fatty, Marsh-gas, or Methane Series. The Benzene 
or Aromatic Series has great general chemical interest. The Ter- 
pene Series has considerable pharmaceutical interest. 

A very large number of compounds of carbon will thus be brought 
under notice — far larger than that of any other element. The mere 
number, however, need not dismay the student. The relation of the 
derivatives of one hydrocarbon to that hydrocarbon will be found to 
obtain between the next set of derivatives studied with their hydro- 
carbon, and so on ; hence as the student progresses he is soon look- 
ing for compounds which he already expects to exist, instead of 
finding his mind overburdened with what at first sight he might 
fear would be an intricate and endless subject. 

The methods of examining morbid urine will afterward be experi- 
mentally considered. There will then remain to be studied by the 
medical and pharmaceutical pupil, but by aid of some other guide 
than the author's, certain galenical as distinguished from chemical 
substances, solid and liquid, which can only be fairly regarded from 
a pharmacist's rather than a chemist's point of view, and a still 
larger number, doubtless, not yet brought within the grasp of chem- 
ist or pharmacist, and of which, therefore, we must at present be 
content to remain in ignorance. An opportunity, however, will be 
afforded of noticing the effect of such indefinite organic matter as a 
vomit, or the contents of a stomach, in masking or preventing the 
reactions by which mineral and vegetable poisons are detected. 

A section on quantitative analysis will complete the Manual. 



QUESTIONS AND EXERCISES. 



What do you understand by Organic Chemistry ? — Give methods of 
ascertaining the presence of carbon, hydrogen, and nitrogen in organic 
compounds. — Give an outline of the methods by which the quantities of 
carbon, hydrogen, oxygen, and nitrogen are determined in organic com- 
pounds. — How would you convert centesimal into " atomic " composi- 
tion ? — Define empirical, molecular, and rational formulas. — How is the 
constitution of an organic compound ascertained ? — What do you under- 
stand by graphic chemical formulae ? — Define " stereo-chemical " formulae. 
— Give graphic formulas of two or three saturated hydrocarbons. — What 
do you mean by an organic radical? — Give illustrations. — Give the gen- 
eral formulas of different series of hydrocarbons, with special illustra- 
tions. — Define substitution as understood in organic chemistry. 



396 ORGANIC CHEMISTRY. 



THE PARAFFIN SERIES OF HYDROCARBONS. 

Methane, Marsh-gas, Light Carburetted Hydrogen, Methyl Hy- 
dride, Fire-damp, CH 4 . — This gaseous hydrocarbon may be made 
from its elements by uniting the carbon with sulphur and the 
hydrogen with sulphur or oxygen, and passing these over red-hot 
copper. It occurs naturally in coal-mines and in the mud-volcanoes 
of the Crimea, is frequently associated with the crude petroleum 
that issues from the earth, and is constantly rising in bubbles to 
the surface of stagnant pools in marshy places. It is a non-luminous 
constituent of ordinary coal-gas. It is inodorous and colorless. It 
may be produced by acting on methyl iodide with zinc on which 
copper has been deposited, and in other theoretically interesting- 
ways, but economically by heating a mixture of 2 parts of dry 
sodium acetate, 3 of lime, and 2 of caustic soda, or, better, potash. 

CHyCOONa + NaOH = CH 4 -f C0 3 Na 2 

Sodium acetate. Soda. Methane. Sodium carbonate. 

Two Notes on the Notation of the Foregoing and Similar Formula?, 
and on the Constitution of Salts. — (a) Soda, NaHO, contains biva- 
lent oxygen, univalent sodium, and univalent hydrogen. The 
chemical valency of the oxygen atom is double that of either of the 
other atoms — a relationship perhaps better realized if the symbol 
for the oxygen be placed between those of hydrogen and sodium, 
NaOH, or HONa. So HOK, HOH, etc. The student must expect 
to find the symbols of a formula placed where apparently they will 
best reflect our knowledge of the structure of the molecule pictured. 
(b) Acetic acid, C 2 H 4 2 , by action of chlorine (presented as PC1 3 ) 
loses hydroxyl, OH, and yields acetyl chlorine, C 2 H 3 0C1. Hence 
acetic acid would seem in constitution to be acetyl hydrate, C 2 H 3 OOH, 
especially when we find that acetyl chloride by reaction with water, 
HOH, yields again acetic acid (and HC1). Sodium will only dis- 
place one atom of hydrogen from water, yielding HONa, and will 
only displace one atom of hydrogen from acetic acid, yielding sodium 
acetate, C 2 H 3 0"ONa. Further, chlorine will not displace more than 
one portion or atom of hydroxyl, OH, from acetic acid. So that 
three atoms of the hydrogen in acetic acid apparently perform dif- 
ferent functions to those of the fourth atom, and, apparently, the 
two atoms of oxygen perform different functions. Hence our neces- 
sity for separating in the formula the letters representing those 
atoms, C 2 H 3 0'OH. Once more, acetates may be formed from two 
different methyl compounds — sodium acetate by the direct combina- 
tion of sodium methide, CH 3 Na, and carbonic acid gas, C0 2 , giving 
CH 3 CO'ONa ; and ammonium acetate by the combination of methvl 
cyanide, CH 3 CN, with water (2HOH), yielding CH 3 -COONH 4 . 
From these and other facts and modes of reasoning arise our justifi- 
cation — from them, indeed, comes the necessity — for thus extending 
the formulae for acetates. Less extended formulae are of course 
correct, and even occasionally more useful : C 2 H 4 2 , C 2 H 3 2 H, 
C 2 H 3 0'OH, CH 3 COOH form an illustration of a set of formulae for 
a substance, either member of which set may be used according to 



PARAFFIN HYDROCARBONS. 397 

circumstances. (See also pp. 286 and 299.) The following would 
be reasonable graphic formulae, like those on p. 390 or 392 : 

H H 

H-C-C<2_ H H -(U<°_ Na 

H H 

Acetic acid. Sodium acetate. 

CI H 

oi-Lc<g_ H H -c-c<ci 

CI H 

Trichloracetic acid. Acetyl chloride. 

Ethane, C 2 H 6 , Dimethyl, Ethyl Hydride. — This is one of the con- 
stituents of crude petroleum. It also results on heating ethyl iodide 
with granulated zinc or zinc covered with copper, and then adding 
water to the zinc iodide and zinc ethide first produced. 
2Zn + 2C 2 H 5 I = Zn(C 2 H 5 ) 2 + Znl 2 
Zn(C 2 H 5 ) 2 + 20H 2 = 2C 2 H 6 + Zn(OH) 2 . 

Ethane is sometimes regarded as dimethyl or methylmethane, 
CH3CH3 ; that is to say, as being derived from methane by the substi- 
tution of an atom of hydrogen in methane, CH 4 , by methyl, CH 3 : 
its properties, however, are not those of a radical. It is also con- 
sidered to be ethyl hydride, C 2 H 5 H : its properties, however, are not 
those of such a substance. The other hydrocarbons of the paraffin 
series are also similarly regarded as containing radicals. Such 
views of constitution are useful as enabling composition to be 
remembered and relationships to be realized, especially if their 
hypothetical character be fully recognized ; but these hydrocarbons 
are apparently single homogeneous substances, and, whatever other 
views of their constitution be held, this last should be dominant. 

Propane, Methyl Ethyl, C 3 H 8 . — This gas, like methane, occurs dis- 
solved in the Pennsylvanian petroleum springs. 

Tetrane or Butane, C 4 H 10 . — Two varieties exist, normal butane 
or diethyl, C 2 H 5 C 2 H 5 , found in petroleum, and isobutane or trimethyl 
methane, CH(CH 3 ) 3 , formed by artificial means. 

Turning back to the highly extended formulas for methane, ethane, 
propane, and butane given on p. 391, the reader will see why there 
should only be one ethane or propane, while two butanes (two 
methyl-propanes) are possible. We can but replace one of the atoms 
of hydrogen, H, in methane, CH 4 , to form ethane, CH 3 -CH 3 , and it 
matters not which ; hence only ethane (one ethane) can result. In 
ethane, CH 3 CH 3 , if an atom of hydrogen be displaced by methyl, 
CH 3 , it can but be a hydrogen atom of one of the two methyl groups 
(CH 3 'CH 3 ), and it matters not which, though two cZf-derivatives may 
exist. (See the respective ethylene and ethylidene chlorides, p. 
411.) But in propane, CH 3 -CII 2 CII 3 , a CH 2 group exists, as well as 
CH 3 groups. Now, CH 2 is a different group to CH 3 ; hence if we 
18 



398 ORGANIC CHEMISTRY. 

displace one of its two atoms of hydrogen (it matters not which) by 
methyl to get butane, we should expect to get a butane of different 
properties to the butane obtained by displacing one of the atoms of 
hydrogen in the methyl groups by methyl ; and two butanes, and 
two only, do actually exist. Normal butane may be thus formulated, 
CH 3 CH 2 CH 2 'CH 3 , while isobutane would be either CHg'CHg-CH'CHg, 
or a practically identical formula, CHgCH'CHgCH^. 

H H H H HCH 3 H H H H 

H— C— C— C— C— H H— C— C— C— H or H— C— C— C— H 

I I I I III III 

HHHH HHH HCH 3 H 

Butane. Isobutane. 

Pentane, C 5 H 12 . — Three varieties are possible, and three only; 
three are known, and three only 5 the second, or isoamylic hydride, 
yielding the ordinary amylic alcohol and valerianic acid, 

Hexanes, C 6 H u . — Five are possible, five are known. 

Heptanes, C 7 H 16 . — Nine are possible, five are known. 

Octanes, C 8 H 18 . — Eighteen isomers possible, three known. 

Nonane, C 9 H 20 ; Decane, C 10 H 22 ; and every paraffin hydrocarbon 
up to C 24 H 50 , as well as some others and derivatives of far higher 
members of the paraffin series of hydrocarbons, are known. 

Petroleum Spirit, Paraffin Oil, Paraffin. 

Benzinum, U. S. P.; Benzin [Petroleum Spirit, B. P.) Pentane, 
C 5 H 12 , Hexane, C 6 H U , etc., known also as Benzoline, Petroleum Ben- 
zin, and Peti^oleum Ether, "is a colorless, very volatile, and highly 
inflammable liquid obtained from petroleum, and consisting of a 
mixture of the lower members of the paraffin or marsh-gas series of 
hydrocarbons. Boiling-point, 122° to 140° F. (50° to 60° C). Specific 
gravity, about 0.670 to 0.700." (Benzine or benzol is quite a dif- 
ferent fluid ; vide Index.) 

Paraffin Oil, the Paraffinum Liquidum of the German Pharma- 
copoeia, is a mixture of the higher fluid members of the paraffin 
series of hydrocarbons, a clear oily liquid obtained from petroleum 
after distilling off the lower-boiling portions. Specific gravity, not 
below 0.840. Boiling-point, not below 360° C. (680 F.). Digested 
and agitated with warm sulphuric acid for a day or two, the oil is 
not colored and the acid only tinged brown ; metallic sodium under 
similar conditions is not tarnished. Petrolatum Liquidum. U. S. P., 
is similar to the above, having a specific gravity between 0.875 and 
0.945 5 is soluble in chloroform, ether, carbon bisulphide, benzol, 
benzin, and the fixed and volatile oils. Alcohol boiled with the oil 
should not become acid. Soft Paraffin (Petrolatum Molle, U. S. P. 
1890, the Petrolatum of U. S. P. 1880), Soft Petroleum Ointment, 
officially termed Paraffinum Molle in England, Unguentum Paraffini 
in Germany, Petroleine in France, and " known in commerce by 
various fanciful names," is a semi-solid mixture of paraffins, usually 



CHLOROFORM. 399 

obtained by purifying the less volatile portions of petroleum. It is 
u white or yellowish,translucent, soft, greasy, free from acidity, alkalin- 
ity, or any unpleasant odor or flavor even when warmed to 120° F. 
(48.9° C). Specific gravity at the melting-point, from about 0.840 
to 0.870. Melts at 95° to" 105° F. (35° to 40.5° C.) or even some- 
what higher ; volatilizes without giving acrid vapors, and burns with 
a bright flame, leaving no residue ; insoluble in water, slightly 
soluble in absolute alcohol, freely soluble in ether, chloroform, 
benzol, etc. It is not saponified by solutions of alkalies.'' — B. P. 
Hard Paraffin {Petrolatum Spissum, Hard Petrolatum, Hard Petro- 
leum Ointment, U. S. P. 1890) {Paraffin Durum, B. P.), {Petrolatum, 
U. S. P., 1880), commonly termed Paraffin Wax or simply Paraffin, 
is " a mixture of several of the harder members of the paraffin series 
of hypocarbons : usually obtained by distillation from shale, separa- 
tion of the liquid oils by refrigeration, and purification of the solid 
product. It is colorless, semi-transparent, crystalline, inodorous, and 
tasteless ; slightly greasy to the touch. Specific gravity, 0.82 to 
0.94. Insoluble in water, slightly soluble in absolute alcohol, freely 
soluble in ether. It melts at 110° to 145° F. (43.3° to 62.8° C), 
and burns with a bright flame, leaving no residue." 

Paraffin resists all ordinary reagents (hence the original name 
Paraffin, from parum, affinis, without affinity), but may, by continued 
boiling with sulphuric acid and solution of potassium bichromate, be 
oxidized to cerotic acid, C 27 H 54 2 , and by continued digestion with 
nitric and sulphuric acids yields acids of the acetic series and 
inic acid, C 24 H 48 2 (Pouchet). 



Substitution-Products of Methane. — The paraffins all form sub- 
stitution-derivatives with the halogens, chlorine acting energetically, 
bromine less so, and iodine scarcely at all. In the preparation of 
chlorine and bromine substitution-products by acting on the hydro- 
carbons, the mono-derivatives are always mixed with the higher 
derivatives, even though the quantities are taken in relation to their 
combining proportions ; thus, if methane and chlorine are mixed in 
the proportion of CH 4 -4- Cl 2 , not only will monochloromethane, or 
methyl chloride, CH 3 C1, be formed, but dichloromethane, CH 2 C1 2 , and 
trichloromethane, CHC1 3 , with free hydrogen. The best method of 
obtaining the mono-derivatives is to act on the alcohols by haloid 
acids or by phosphorus compounds : 

CH3OH + HC1 = CH3CI + H 2 
3CH 3 OH + PC1 3 = 3CH 3 C1 + PH 3 3 . 

Chloroform. 

Trichloromethane, or Chloroform, CHC1 3 may be made by act- 
ing on methane with chlorine, as already indicated : 

CH 4 4- 3C1 2 == CHC1 3 -I- 3HC1 ; 
also as shown on p. 402, but on a larger scale by the official 
process, as follows : 



400 ORGANIC CHEMISTRY. 

Process. — 1 J fluidounces of spirit and 24 of water are placed 
in a retort or flask of at least a quart capacity ; 8 ounces of 
chlorinated lime and 4 of slaked lime are added, the vessel con- 
nected with a condenser, and the mixture heated until distilla- 
tion commences, the source of heat then being withdrawn. The 
condensed liquid should fall into a small flask containing water, 
at the bottom of which about a drachm of chloroform will 
slowly collect. 

Explanation of the Process. — Though there is some doubt as to 
the exact reaction, the following seems to be most probable. The 
calcium hypochlorite believed to be present in the chlorinated lime 
(see the remarks in connection with the latter, p. 114) readily yields 
up oxygen and chlorine to organic substances, the calcium being 
liberated as hydrate. The alcohol used in making chloroform is 
thus probably first converted into aldehyde : * 

2CH 3 CH 2 OH + 2 = 2CH 3 COH -f 2H 2 

Alcohol. Oxygen. Aldehyde. Water. 

The action of chlorine on aldehyde then probably gives chloral 
(chlor-aldehyde) : 

CRyCOH + 3C1 2 = 2CC1 3 -C0H 4- 3HC1 

Aldehyde. Chlorine. Chloral. Hydrochloric 

acid. 

The hydrochloric acid being at once neutralized by some of the 
liberated calcium hydrate to form calcium chloride and water, more 
freed calcium hydrate and chloral gives calcium formate and chloro- 
form. 

2CCVCOH + Ca2HO = (HCOO) 2 Ca + 2CHC1 3 

Chloral. Calcium Calcium Chloroform, 

hydrate. formate. 

Or, irrespective of the chemistry of each step in the process, and 
regarding only the materials and the products, four molecules of 
alcohol and eight of calcium hypochlorite give two of chloroform, 
three of calcium formate, five of calcium chloride, and eight of 
water, thus : 

4CH 3 CH 2 OH + 8CaCl 2 2 = 

Alcohol. Calcium 

hypochlorite. 

2CHC1 3 -f 3(H-COO) 2 Ca 4- 5CaCl 2 4- 8H 2 

Chloroform. Calcium Calcium Water, 

formate. chloride. 

The calcium hydrate placed in the generating vessel is not essen- 
tial, but is useful in preventing secondary decompositions, the calcium 
hydrate obtainable from the reaction being insufficient for this 
purpose. 

* The special formulae for alcohol, aldehyde, and the formate used in 
the accompanying equations will be better understood when the consti- 
tution of alcohols and acids has been considered. 





IODOFORM. 401 

Chlorine converts chloroform into tetrachloromethane or carbon 
tetrachloride, CC1 4 , completing the chlorine substitution-products of 
methane. 

-CI 
CI 

Trichloromethane Tetrachloro- 
(chloroform). methane 

(carbon tetra- 
chloride). 

Chloroform is purified by shaking it with water, and then with 
pure sulphuric acid (containing no trace of nitric acid), which chars 
and removes hydrocarbons, etc., but does not affect chloroform. It 
is freed from any trace of acid by agitation with lime, and from 
moisture by solid calcium chloride. It is finally rectified. 

Properties. — The sp. gr. of pure chloroform is at least 1.500, per- 
haps higher. It is liable to slowly decompose when exposed to air 
and light: 4CHC1 S + 30 2 = 4C0C1 2 + 2H 2 + 2C1 2 . The resulting 
chlorine may be detected by zinc iodide and starch, and the carbon 
oxychloride by baryta-water : 2C0C1 2 + 2H 2 =2C0 2 + 4HC1. To 
render it stable, a minute amount (one volume in one hundred or less) 
of absolute alcohol is necessary : hence the specific gravity of 
medicinal chloroform is about 1.497 (Chloroformum, U. S. P., the 
Purified Chloroform of the 1880 Pharmacopoeia). It readily and 
entirely volatilizes at common temperatures, having, to the last 
drop, its pleasant characteristic odor. It has a sweetish taste, is 
limpid, colorless, soluble in alcohol (1 in 16 gives Spiritus Chloro- 
formi, U. S. P.) and ether, and slightly in water. It may be so 
frozen at low temperatures that any impurities shall remain in the 
still fluid portion (Pictet). Boils at 142° F, It burns with a slug- 
gish, green, smoky flame. It reduces Fehling's solution. It should 
be neutral to test-paper, indicating absence of acid ; give no precipi- 
tate with solution of silver nitrate, indicating absence of ordinary 
chlorides ; remain colorless when heated with potash, indicating 
absence of aldehyde ; and give no more color than is producible by 
the absolute alcohol that is present to any sulphuric acid with which 
it may be shaken, even after the mixture has been set aside for half 
an hour, indicating absence of hydrocarbons, etc. Alcohol may be 
detected by the iodoform test (see Index), or by shaking with a little 
of the dye termed " Hofmann's violet," which gives the chloroform 
a purple tint if alcohol be present, but affords no color with pure 
chloroform. At the temperature of melting ice chloroform unites 
with water to form a crystalline compound, CHC1 3 ,18H 2 0. 

Aqua Chloroformi, U. S. P., the official chloroform-water, is made 
by saturating a sufficient quantity of water with chloroform. 

Iodoform. 

Tri-iodomeihane, or Iodoform, CHI 3 (lodoformum, U. S. P.), 
analogous in constitution to chloroform, the iodine occupying 



402 ORGANIC CHEMISTRY. 

the place of the chlorine, is made by mixing together 1 part of 
alcohol, 2 parts of crystallized sodium carbonate, and 10 parts 
of water, the whole being heated to about 150° F., and 1 part 
of iodine gradually added in small portions. When the fluid 
becomes colorless the iodoform is allowed to settle. The iodo- 
form is collected on a filter, washed thoroughly with water, and 
dried between filtering-paper. (This reaction forms a very 
delicate means of testing the presence of alcohol. Vide "Alco- 
hol, Test for," in Index.) 

Iodoform occurs as yellow, shining, six-sided scales. It is volatile 
at ordinary temperatures. Almost insoluble in water, soluble in 
alcohol or ether. Warmed with an alcoholic solution of potash, 
potassium formate and iodide are produced : CHI 3 -f- 4KOH = 
HCOOK + 3KI + 2H 2 ; and the resulting fluid, heated with a little 
nitric acid, yields free iodine, recognized by its color or by giving a 
blue color with starch. 

Chloroform, Iodoform, and Bromoform may also be obtained on 
passing a current of electricity through hot strong alcohol containing 
potassium chloride, iodide, or bromide, respectively, carbonic anhy- 
dride being simultaneously supplied ; or, again, by the action of 
bleaching-powder, or a mixture of chlorinated soda with potassium 
bromide or iodide, on acetone. The latter, " ketone chloroform,' 1 is 
a commercial article. 

Substitution-products of Ethane.— Ethane, like methane, 
yields substitution-derivatives. Monobromethane, ethyl bromide, 
ethylic bromide, or hydrobromic ether, C 2 H 5 Br, may be prepared 
by gradually adding 6 parts of bromine to a mixture of 6 
parts of ethylic alcohol and 1 of amorphous phosphorus con- 
tained in a flask fitted with an upright condenser, care being 
taken to keep the apparatus cool. 

5C 2 H 5 OH + PBr 5 = 5C 2 H 5 Br -f H 3 P0 4 + H 2 0. 

When all the bromine has been added, the mixture is poured 
into a retort and distilled over a water-bath, the resulting 
ethylic bromide freed from excess of bromine by washing with 
a small quantity of dilute soda or potash, then washed with 
water, and rectified over calcium chloride and redistilled. 

For its preparation on a large scale DeVrij's method is preferable, 
C 2 H 5 HS0 4 + KBr = C 2 H 5 Br + KHS0 4 (see Pharm. Journ., Feb. 15, 
1879), or the same method as modified by Greene (P. J., July 12, 
1879), by Remington (P. J., May 29, 1880), or by Wolff (P. J., July 

3, 1880). 

Mon-iodo-ethane-, ethyl iodide or ethylic iodide, C 2 H 5 I, may be 
made, like the bromide, by mixing 7 to 8 parts of amorphous 
phosphorus and 70 of absolute alcohol with 100 parts of iodine. 
The complete decomposition takes three or four hours, after 









SPIRIT OF NITROUS ETHER. 403 

which it may be treated as above. It should be kept in a dark 
place, as light favors decomposition and liberation of iodine. 

The paraffins give rise to many substitution-derivatives by dis- 
placement of their hydrogen by compound acidulous radicals. The 
following, chiefly from ethane and pentane, are of pharmaceutical 
interest : 

Spirit of Nitrous Ether. 

Ethyl Nitrite, Nitrous Ether, C 2 H 5 N0 2 .— A "spirit," probably 
containing nitrous ether, was one of the earliest known medicinal 
compounds, its discovery being generally ascribed to Raymond 
Lully. 

Process. — To a third of a test-tubeful of rectified spirit add 
about a tenth of its bulk of sulphuric acid, rather more of 
nitric acid, and warm the mixture ; as soon as ebullition com- 
mences the vapor of nitrous ether (with other substances) is 
evolved, recognized by its odor. A long bent tube, kept very 
cool, may be adapted by a perforated cork to the test-tube, and 
thus a little of the product be condensed and collected. 

The above process, conducted on a larger scale, with definite quan- 
tities of materials and slight modifications, temperature regulated 
by a thermometer and a well-cooled condenser, etc. (jsee p. 127), is 
the official process for the preparation of a concentrated solution of 
nitrous ether, etc. in spirit ; diluted with nearly three times its bulk 
of rectified spirit, it forms the official variety of the " spirit of nitrous 
ether" (Spiritus JEtheris Nitrosi, U. S. P.) of pharmacy, containing 
about 5 per cent, of the crude ether. 
" Take of— 

Sodium nitrite 770 grms. 

Sulphuric acid 520 " 

Sodium carbonate 10 " 

Potassium carbonate (anhydrous) .... 30 " 

Deodorized alcohol sufficient. 

Water sufficient." 

Dissolve the sodium nitrite in 1000 cc. of water in a suitable 
flask connected with a condenser kept cold by ice-cold water ; then 
add 550 cc. of deodorized alcohol, and mix well. Through a cork 
fitted into the mouth of the flask insert a funnel-tube dipping below 
the surface of the liquid. With the condenser connect a receiver, 
and keep this surrounded by a freezing mixture. Then gradually 
introduce into the flask, through the funnel-tube, the sulphuric acid, 
previously diluted with 1000 cc. of water. Distillation will usually 
commence before the whole of the acid has been added. When all 
the acid has been introduced, regulate the distillation by the appli- 
cation or withdrawal of a gentle heat until no more nitrous ether 
distils over. Wash the distillate, first, with' 100 cc. of ice-cold 
water to remove any alcohol which may have passed over, and then 
remove any traces of acid by washing the ether with 100 cc. of ice- 
cold water in which the sodium carbonate had previously been dis- 



404 ORGANIC CHEMISTRY. 

solved. Carefully separate the ether from the aqueous liquid, and 
agitate it, in a well-stoppered vial, with the potassium carbonate to 
remove traces of water. Then filter it through a pellet of cotton, 
in a covered funnel, into a tared bottle containing 2000 cc. of de- 
odorized alcohol. Ascertain the weight of the nitrous ether filtered 
into the alcohol by noting the increase of weight of the tared bottle 
and contents, and then add enough deodorized alcohol to make the 
mixture weigh 22 times the weight of the nitrous ether added. 
Lastly, transfer the product to small, dark amber-colored, well- 
stoppered vials, and keep them in a cool place, remote from lights 
or fire. 

Disregarding the other products, the following equation represents 
the chief decomposition that occurs in the operation : 

2C 2 H 5 OH + 2NaN0 8 + H 2 S0 4 = 

Alcohol. Sodium nitrite. Sulphuric acid. 

2C 2 H 5 N0 2 + 2H 2 + Na 2 S0 4 
Nitrous ether. Water. Sodium sulphate. 

Properties. — Spirit of Nitrous Ether, U. S. P., is " a clear, mobile, 
volatile, and inflammable liquid of a pale-yellowish or faintly green- 
ish-yellow tint, having a fragrant, ethereal, and pungent odor free 
from acridity, and a sharp, burning taste. Sp. gr. 0.836 to 0.842 at 
15° C. When freshly prepared, or even after being kept for some 
time with but little exposure to light and air, it is neutral to litmus- 
paper. When long kept or after having been freely exposed to air 
and light, it acquires an acid reaction, but it should not effervesce 
when a crystal of potassium bicarbonate is dropped into it. If a 
test-tube be half filled with the ' spirit,' and put into a water-bath 
heated to 65° C. (149° F.) until it has acquired this temperature, 
the ' spirit ' should boil distinctly upon the addition of a few small 
pieces of broken glass." It should not effervesce, or only feebly so, 
when shaken with a little sodium bicarbonate (showing absence of 
appreciable quantities of free nitrous, acetic, or other acid). Any 
aldehyde, which is generally present, may be detected by the potash 
test (see " Aldehyde, Test for," in Index). The great tendency of 
this aldehyde to become converted into acetic acid by the absorption 
of oxygen from the air renders spirit of nitrous ether unstable, and 
pharmacists are obliged to neutralize such acid, generally by potas- 
sium bicarbonate, before adding it to medicines containing iodides, 
etc. 

A very old variety of spirit of nitrous ether, or rather "sweet 
spirit of nitre," still largely sold in Great Britain, is made from 
spirit of wine and nitric acid, as ordered in the London Pharma- 
copoeias, except that the distillation is continued until the product 
has a sp. gr. of 0.850. It may contain little or no nitrite, but is 
popular. 

Test. — Any nitrous radical may be detected by adding ferrous 
sulphate and sulphuric acid to some of the spirit of nitrous ether, 
the usual black compound being produced. 

Official (U. S. P.) Test of Strength.— ■" If 5 cc. of recently pre- 
pared spirit of nitrous ether be introduced into a nitrometer, and 
followed, first, by 10 cc. of potassium iodide, and then by 10 cc. of 






SPIRIT OF NITROUS ETHER. 405 

sulphuric acid, the volume of nitrogen dioxide generated at the 
ordinary indoor temperature (assumed to be at or near 25° C. or 
77° F.) should not be less than 55 cc. (corresponding to about 4 per 
cent, of pure ethyl nitrite)." 

(For the detection of methyl alcohol in spirit of nitrous ether 
vide "Methylated Sweet Spirit of Nitre" in Index.) 

Pure Ethyl Nitrite. — Dr. Leech states that the physiological and 
the therapeutic action of "spirit of nitrous ether" is similar to that 
of an alcoholic solution of ethyl nitrite of similar nitrous strength. 
The nitrite was prepared for Dr. Leech in the Research Laboratory 
of the Pharmaceutical Society of Great Britain by Hare's process 
of mixing sodium nitrite, sulphuric acid, and alcohol at a low tem- 
perature, but perhaps for the first time in a pure condition. The 
nitrite separates as a pale yellow layer. It may be washed rapidly 
with a little water and dried with anhydrous potassium carbonate. 
As it is decomposed by prolonged contact with water, Dr. Leech was 
supplied, according to suggestions and experiments by the late John 
Williams, with a pure solution of the ether in absolute alcohol con- 
taining 5 per cent, of glycerin as a preservative. It should be dis- 
pensed and used from small bottles to avoid loss by volatilization 
and to prevent absorption of moisture from the air. 

2NaN0 2 + H 2 SO, + 2C 2 H 5 OH = 2C 2 H 5 N0 2 Na 2 S0 4 + 2H 2 

Sodium Sulphuric Ethyl Ethyl Sodium Water, 

nitrite. acid. hydrate. nitrite. sulphate. 

Nitro- compounds. — There are two nitro-ethylic compounds having 
similar composition, but differing very much in properties — namely, 
ethyl nitrite (C 2 H 5 N0 2 ), which boils at 63.5° F. (17.5° C.) and has a 
sp. gr. of 0.900 (at 0° C. ; water = 1 ; 0.917 to 0.920 ; Dunstan and 
Dymond), and nitro-ethane (C 2 H 5 N0 2 ), which boils at about 235° F. 
(nearly 113° C.) and has a sp. gr. of 1.058. There are also two 
nitro-methylic compounds — namely, methyl nitrite (CH 3 N0 2 ) and 
nitro-methane (CH 2 N0 2 ). The nitrites are easily decomposed ; the 
nitro-compounds are stable. The official spirit of nitrous ether 
contains ethyl nitrite. Possibly the nitrites contain the nitrogen 
in the trivalent or unsaturated condition, while in the nitro-com- 
pounds it is in the quinquivalent or saturated state. Moreover, the 
reaction of the two sets of bodies warrants the conclusion that in 
the nitrites the methyl or ethyl is united to oxygen, in the nitro- 
compounds to the nitrogen. Each hydrocarbon furnishes only one 
mono-nitrite ; each hydrocarbon furnishes only one mono-nitro com- 
pound. The nitrites are, the nitro-compounds are not, saponifiable ; 
on reduction the nitrogen of the former does not, while that of the 
latter does, remain with the radicals, yielding amines. There are 
two similar nitro-amylic compounds. 



Methyl nitrite, CH 3 -0-]N=0. 


Nitro-methane, 


CHa-N^g 


Ethyl nitrite, C 2 H 5 -0-N=0. 


Nitro-ethane, 


W-nCo 


Amyl nitrite, C 5 H n — O— N=0. 

18* 


Nitro-pentane, 


C 5 H u -<°, 



406 ORGANIC CHEMISTRY. 

Acetic Ether, or Ethyl Acetate. 

Ethyl Acetate, or Acetic Ether, CH 3 COOC 2 H 5 or C 2 H 5 C 2 H 3 2 . 
— To a little dried sodium acetate, in a test-tube, add a small 
quantity of rectified spirit of wine and some sulphuric acid. 
Adapting a long bent tube in the usual manner, heat the test-tube 
and so distil over acetic ether, which may be collected in another 
test-tube, kept cool by partial immersion in cold water. 

The official proportions {JEther Aceticus, B. P.) are: rectified 
spirit, 32^ fluidounces ; sulphuric acid, 32J fluidounces ; sodium 
acetate, 40 ounces ; potassium carbonate, freshly dried, 6 ounces. 
To the spirit slowly add the acid, keeping the fluid cool, and, the 
product being cold, add the acetate, mixing thoroughly. Distil 45 
fluidounces. Digest the distillate with the potassium carbonate for 
three days in a stoppered bottle. Separate the ethereal fluid, and 
again distil until all but about 4 fluidounces have passed over. 
Preserve the resulting acetic ether in a well-closed bottle and in a 
cool place. It is a colorless liquid with an agreeable ethereal odor. 
JEther Aceticus, U. S. P., has the specific gravity 0.889 to 0.897. 
Boiling-point, about 76° C. (168° F.). If a small portion of the 
ether be carefully poured upon some concentrated sulphuric acid, 
no dark ring should be developed at the point of contact of the two 
layers (absence of readily carbonizable organic impurities). Solu- 
ble in all proportions in rectified spirit and in ether. 

" When 25 cc. of acetic ether are shaken, in a graduated tube, 
with 25 cc. of water just previously saturated with the ether, upon 
separation the ethereal layer should not measure less than 24.5 cc. 
(absence of an undue proportion of alcohol or water)." 

C 2 H 5 OH + CH,-CO-ONa + H 2 S0 4 = 

Ethyl hydrate. Sodium acetate. Hydrogen sulphate. 

CH 3 COOC 2 H 5 + NaHS0 4 + HOH 

Ethyl acetate. Sodium and Hydrogen 

hydrogen sulphate. hydrate. 

Amyl Acetate, CHg-CO-OCaH^ or C 5 H n C 2 H 3 2 . (Fousel oil, or 
ordinary amylic alcohol, is a mixture of two or more alcohols derived 
from pentane, but the derivatives may be simply termed amyl com- 
pounds ; vide Pentylic or Amylic Alcohol in Index.) 

To a small quantity of amylic alcohol in a test-tube add some 
potassium acetate and a little sulphuric acid, and warm the mix- 
ture ; the vapor of amyl acetate is evolved, recognized by its odor, 
which is that of the jargonelle pear. If a condensing-tube be 
attached, the essence may be distilled over, washed by agitation 
with water to free it from alcohol, and separated by a pipette. 

CH.-CO-OK + C 6 H u OH + H 2 SQ 4 = 

Potassium Amylic Sulphuric 

acetate. alcohol. acid. 

CHs-CO-OCsHn + KHS0 4 + H 2 

Amyl acetate. Acid potassium Water, 

sulphate. 



AMYL NITRITE. 407 

Fruit-essences. — Amyl acetate, prepared with the proper equiva- 
lent proportions of constituents, as indicated by the above equation, 
is largely manufactured for use as a flavoring agent by confectioners. 
Amyl valerianate (0 5 H n C 5 H 9 2 ) is similarly used under the name 
of apple oil. Ethyl butyrate (C 2 H 5 C 4 H 7 2 ) closely resembles the 
odor and flavor of pine-apple ; ethyl cenanthylate (C 2 H 5 C 7 H ]3 2 ) 
recalls greengage ; ethyl pelargonate (C 2 H 3 C 9 H 17 2 ), quince ; ethyl 
suberate (C 2 H 5 C 8 H 12 4 ), mulberry ; ethyl sebacate (C 2 H 5 C 10 H 16 O 4 ), 
melon. Salicylic aldehyde (the old salicylol or salicylofis acid), 
C 6 H 4 'OH'COH, is the essential oil of meadow-sweet (Spirosa 
ulmaria), and may be prepared artificially by the oxidation of salicin. 
(Vide Index, " Salicin.") Acid methyl salicylate (CH 3 HC 7 H 4 3 ), or 
gaultheric acid, forms the chief part of the essential oil of winter- 
green (Gaultheria procumbens) , the fresh leaves of which yield 
about 0.4 per cent, of oil. Acid methyl salicylate, produced by 
synthesis, is official (Methyl Salicylas, U.-S. P.). It is a colorless, 
optically inactive liquid, soluble in alcohol, glacial acetic acid, and 
carbon bisulphide. The white precipitate produced by adding 
sodium hydrate to a solution of methyl salicylate should dissolve at 
100° after a few minutes ; if this liquid be diluted and excess of 
hydrochloric acid added, the precipitate formed should, after being 
recrystallized, answer to all the tests of purity and identity for 
salicylic acid. Oil of sweet-birch (Betula lento) is methyl salicylate, 
and is official — Oleum Betulce Volatile, U. S. P. Salicylic aldehyde 
may also be prepared artificially by heating chloroform and sodium 
phenol. Salicylic acid (C 6 H 4 'OHCOOH) can be obtained from 
methyl salicylate, but more cheaply from carbolic acid. 

By mixing such ethereal salts (alkyl salts or esters ; vide Index) 
with each other and with essential oils in various proportions the 
odor and flavor of nearly every fruit may be fairly imitated. (For 
a set of formulae of fruit-essences see Pharmaceutical Journal, May 
17, 1879.) 

Amyl Nitrite, or Nitrite of Amyl. 

Amyl Nitrite (Amyl Nitris, U. S. P.) (C 5 H 1} N0 2 ).— This may be 
prepared on the large scale by the direct action of nitric acid on 
amylic alcohol, the nitric acid being reduced to nitrous by a portion 
of the alcohol, and valerianic aldehyde with valerianic acid being 
produced. The heat must be very carefully regulated or the reac- 
tion may become extremely violent ; indeed, with small quantities 
a violent explosion may occur. For experimental purposes it is 
preferable to pass nitrous gases, generated by the action of nitric 
acid on white arsenic or on starch, into the- amylic alcohol (kept 
cool by standing the vessel in cold water) until the alcohol is sat- 
urated. The product is shaken with an aqueous solution of potas- 
sium hydrate or carbonate to remove free acids, and the oily liquid 
then separated and distilled. The portion distilling between 205° 
and 212° F. is the amyl nitrite. 

The official amyl nitrite is a yellowish ethereal liquid ; sp. gr. of 
liquid should be between 0.870 and 0.880, of vapor about 4.03 ; boil- 
ing-point, 96° C. (205° F.) ; soluble in spirit of wine, insoluble in 



408 ORGANIC CHEMISTRY. 

water ; converted by fused caustic potash into potassium valerian- 
ate : exposed to the air, it yields amy lie alcohol. If of good quality 
(for physiological purposes, although perhaps not chemically pure) 
about 80 per cent, (principally isoamyl nitrite) will distil between 
194° and 212° F. (90° to 100° C), the bulb of the thermometer being 
in the vapor and not touching the residual fluid. 

The official and commercial varieties of "nitrite of amyl" are 
well known to be only (" chiefly," B. P.) real amyl nitrite. Since 
the British Pharmacopoeia was published, the staff of the Research 
Laboratory of the Pharmaceutical Society have shown that the fluid 
may contain both alpha-amyl and beta-amyl nitrites, iso-butyl nitrite, 
and propyl nitrite, and have furnished specimens of these substances 
to Professor Cash, who finds that their physiological action is not 
primarily dependent on the amount of their nitrosyl. These nitrites 
are, of course, derived from the corresponding hydrates (see pp. 449 
and 450) present in the amylic alcohol. 

Nitropentane (C 5 H n N0 2 ) is similar to amyl nitrite in composition, 
but differing much in properties. It is obtained by reaction of 
amyl iodide on silver nitrite. It boils at 300° to 320° F. (For 
remarks made respecting the two similar derivatives of ethane see 
p. 405.) 



QUESTIONS AND EXERCISES. 

How would you prepare methane and ethane ? — Give formulae. — Give 
details of the production of chloroform from alcohol, tracing the various 
steps by equations. — Give the formulae and state the constitution of the 
various chlorine derivatives of methane. — How is chloroform purified? — 
State the characters of pure chloroform. — Explain the official process for 
the preparation of nitrous ether. — Give the properties of nitrous ether as 
compared with nitro-ethane. — By what official method is the strength 
of spirit of nitrous ether to be estimated ? — How is ethyl iodide made ? — 
Mention the systematic names of several artificial fruit-essences. — What 
is the formula of amyl nitrite, and how is it prepared ? 



THE OLEFINE SERIES OF HYDROCARBONS. 

The Olefine Series of Hydrocarbons consists of unsaturated hydro- 
carbons, having the general formula C n H 2n . Ethylene, C 2 H 4 ; Pro- 
pylene, C 3 H 6 ; Butylene, C 4 H 8 5 Amylene, C 5 H 10 • Hexylene, C 6 H 12 5 
and Heptylene, C V H 14 , and many others are well known. 

Ethylene, Olefiant Gas, or Heavy Carburetted Hydrogen, C 2 H 4 , is 
the first of this series. It is formed in the destructive distillation 
of coal, and is the chief illuminating constituent of coal-gas. Coal- 
gas consists of 30 to 40 per cent, of methane, 40 to 50 per cent, of 
hydrogen, and from 5 to 7 per cent, of ethylene and its homologues. 
Hydrocarbons, normally fluid, but kept in the vaporous condition 
by the diluents, also contribute materially to the illuminating power 
of gas. The impurities are nitrogen, air, carbolic acid, carbon 
disulphide (CS 2 ), and some badly-smelling sulphur compounds. 



OLEFINE HYDKOCARBONS. 409 

Upward of one hundred and fifty distinct chemical substances have 
been obtained from the solid, liquid, and gaseous products of the 
destructive distillation of coal. 

Preparation. — Ethylene may be prepared by dropping alco- 
hol into a large retort or flask containing 10 ounces of sul- 
phuric acid and 3 ounces of water heated to 160-165° C. The 
gas is washed in cold water and a solution of soda to free it 
from ether, alcohol, and sulphurous acid : 

C 2 H 5 OH + H 2 S0 4 = C 2 H 5 HS0 4 + OH 2 

Alcohol. Sulphuric Ethylhydrogen Water, 

acid. sulphate. 

The product, when further heated, yields ethylene : 

C 2 H 5 HS0 4 =C 2 H 4 + H 2 S0 4 . 

If the ethylene be passed into bromine under water until all 
the bromine disappears, ethylene dibromide, C 2 H 4 Br 2 , or dibrom- 
ethane, will be formed. (For constitution see p. 393.) 

Properties. — A colorless and odorless gas, burning with a lumin- 
ous flame. 

Ethylene Sidphate, C 2 H 4 S0 4 , is said to be contained in " Hoffman's 
anodyne," the Spiritus JEther^is Compositus, U. S. P., a solution of 
25 cc. of ethereal oil, 325 cc. of ether, and 1650 cc. of alcohol. The 
so-called ethereal oil or heavy oil of wine is obtained by digesting 
spirit of wine and sulphuric acid together, then distilling, removing 
any acid from the distillate by washing with lime-water, and expos- 
ing the ethereal fluid to the air to facilitate escape of the more vola- 
tile fluids. The product is a mixture consisting probably of ethylene 
sulphate, ethyl sulphate, ether, dissolved ethylene, and other bodies. 

Glycols. — The olefines form corresponding dihydric alcohols or 
glycols (named from glycol, the first member of the series), and 
these give two sets of aldehvdes and acids. (See also p. 456.) 
Thus: 

CH 2 OH COH 

I ' I 

CH 2 OH COH COH 

Glycollic Glyoxal or 

nu ^rr aldehyde. oxalic aldehyde. 



Glycol. 



CH 2 OH COOH 

I I 

COOH . COOH 

Hydroxyacetic acid, Oxalic acid. 



or glycollic acid. 

Relation of Paraffins to Olefines. 

1st. The paraffins may be converted into olefines either by acting 
on alcohols of the paraffin series by sulphuric acid or by acting on a 
monochloro-paraffin by caustic potash. 

C 2 H 5 C1 + KHO = C 2 H 4 -f KC1 + H 2 

Mouochlorethane. Ethylene. 



410 



ORGANIC CHEMISTRY. 







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ACETYLENE HYDROCARBONS. 411 

Inversely, the olefines may be converted into paraffins. By com- 
bining an olefine with hydrochloric acid a monochloro-paraffin 
results, which, when acted on by nascent hydrogen, yields a 
paraffin. 

C 2 H 4 -f HC1 = C 2 H 5 C1 
Ethylene. Monochlorethane. 

2C 2 H 5 C1 -f 2H 2 = 2C 2 H 6 -f 2HC1 

Monochlorethane. Ethane. 

2d. The bromine, chlorine, and iodine additive derivatives of the 
olefines are either identical or isomeric with the substitution-deriva- 
tives of the paraffins. Thus C 2 H 4 C1 2 is either dichlorethane or ethy- 
lene chloride ; and the additive derivatives with the acids, such as 
hydrochloric, produce mono-substitution derivatives of the paraffins. 
In the case of the chloride, however, C 2 H 4 C1 2 , it has a different boil- 
ing-point and specific gravity according as it is prepared from ethylene 
and chlorine {ethylene chloride, alpha dichlorethane, or the old 
" Dutch liquid") or from monochlorethane (ethyl chloride) and 
chlorine (monochlorethyl chloride, beta-dichlorethane, or ethylidene 
chloride.) The former may be represented by the formula CH 2 C1'- 
CH 2 C1, and the latter as CH 3 -CHC1 2 . It is the former also which 
yields glycol (by reaction of the chloride with silver acetate, and of 
the resulting ethylene acetate with an alkaline hydrate), hence the 
formula of the glycol also must be CH 2 OHCH 2 OH, and not 
CH 3 -CH(OH) 2 : 

CH 2 C1 CELOH 

I I 

CH 2 C1 CH 2 OH 

Methylene chloride Ethylene hydrate 

(Dutch liquid). (glycol). 



THE ACETYLENE SERIES OF HYDROCARBONS. 

The members of the acetylene series, C n H 2n _2, are characterized 
by forming metallic derivatives. Acetylene itself, C 2 H 2 , is formed 
during the passage of electric sparks between carbon points in an 
atmosphere of hydrogen ; it is the only member which can be 
formed directly from its elements. Other members of the series are 
Allylene, C 3 H 4 ; Crotonylene, C 4 H 6 5 etc. The hydroxyl derivative 
of allylene, known as propargyl alcohol, has the formula C 3 H 3 OH. 

Preparation. — Acetylene may be obtained by heating ethylene 
bromide (dibromethane) with caustic potash, and passing the gas 
into a well-cooled ammoniacal solution of cuprous chloride, with 
which it reacts, forming a red precipitate, probably having the for- 
mula C 2 H 2 Cu 2 (Blochmann), called cuprous acetylide. The pure 
acetylene gas may be obtained from the copper compound by heating 
with hydrochloric acid. Acetylene is yielded in a steady stream 
when water is dropped on to barium carbide. Acetylene is also 
formed by the incomplete combustion of coal-gas, as when an air- 
gas burner is lighted below. It has an unpleasant odor, well 
known in every chemical laboratory in which air-gas lamps are 
used. 



412 ORGANIC CHEMISTRY. 

QUESTIONS AND EXERCISES. 

What are the properties of ethylene, and how is it prepared ? — What 
alcohols are derived from the olefine series ? — Mention the relations 
between the paraffins and olefines. — Give three methods of preparing 
acetylene. 

THE TERPENE SERIES OF HYDROCARBONS. 

The terpene series have the general formula C n H 2n -4. Valylene, 
C 5 H 6 , is the lowest, and Terebenthene or Pinene, C 10 H 16 (pure oil of 
turpentine), the most common member of the series. 

The hydrocarbons, called terpenes, C 10 H 16 , are very commonly met 
with in analyzing the volatile oils. Very few of these oils have 
been artificially produced. Their fragrance appears to be due to the 
non-terpenoid constituent (Wallach). They differ from one another 
in the power of deviating a ray of polarized light to the right or 
left. They may be divided into classes, of which several are inter- 
esting in pharmacy : (a) Terpenes or pinenes, boiling at about 156° 
C, and found in ordinary turpentine and other oils ; (6) sylvestrene, 
found in Russian and Swedish turpentine ; (c) phellandrene, lsevo- 
rotatory from Phellandrium aquaticum and dextro-rotatory from euca- 
lyptus oil (p. 417), boiling-point 170° C. ; (d) citrenes {limonenes), 
boiling at about 175° C, and derived from the different species of 
Citrus ; (e) di-pentene, found in some turpentines and oils of camphor 
and elemi 5 (f) terpinene, occurring in oil of cardamoms. Cam- 
phene, fenchene, and terpinolene are terpenes, but do not occur 
naturally in oils. The sesquiterpenes have the formula C 15 H 24 , and 
include canidene, found in oils of cubebs, savin, cade, betel, cam- 
phor, galbanum, patchouli, juniper, asafoetida, colo, and olibanum ; 
caryophillene, found in oil of cloves, and other isomers of these. 
They boil at a much higher temperature than the terpenes, but re- 
semble them in other respects. 

Oil of Turpentine ( Oleum Terebinthince, U. S. P.). — Turpentine 
itself is really an oleo-resin of about the consistence of fresh honey. 
It flows naturally or by incision from the wood of most coniferous 
trees, larch (Pinus Larix) yielding Venice turpentine ; Abies balsamea 
furnishing Canadian Turpentine or Canada Balsam (Terebinthina 
Canadensis, U. S. P.) ; the bark of Pistachia terebinthus, the variety 
termed Chian Turpentine (containing about 1 part of essential oil to 
7 of resin), and the Pinus australis (palustris), P. abies, P. pinaster 
and P. tosda, affording the common American Turpentine (Terebin- 
ihina, U. S. P.). Pinus maritima gives the French or Bordeaux 
Turpentine, and P. picea the old fragrant Strasburg Turpentine. 
By distillation with steam this crude turpentine is separated into 
colophony, rosin or resin, which remains in the still, and essential 
oil of turpentine, often termed simply turpentine, spirit of turpen- 
tine, or " turps,''' 1 which distils over. Mixed with alkali to saturate 
resinous acids and redistilled in a current of steam, oil of turpen- 
tine furnishes about 80 per cent, of rectified oil of turpentine. Pinus 
sylvestris and P. Ledebourii furnish Russian Turpentine, which, 
according to Tilden, consists of two terpenes and cymene, and also 



VOLATILE OILS. 413 

(Wallach) a lsevogyre limonene. This turpentine is probably a by- 
product in the preparation of common wood tar (Pixliquida, U. S. P.) ; 
its odor is very pleasant, quite different from that of ordinary tur- 
pentine. The leaves of the Pinus sylvestris, or Scotch fir, are in 
Germany broken down to a woolly condition, producing pine wool, 
fir wool, or wadding used in making vermin-repelling blankets ; and 
this substance, or, still better, the fresh leaf, by distillation with 
water, yields Fir-wool Oil (Oleum Pint Sylvestris, B. P.), consisting, 
according to Tilden, of two terpenes, like those of Russian turpen- 
tine, and cymene. This oil, diffused through water by aid of mag- 
nesia, forms the Vapor Olei Pint Sylvestris, B. P. The terpene of 
Bordeaux turpentine (terebenthene) rotates a ray of polarized light 
more than, and in the opposite direction to, the terpene of American 
turpentine, Oleum Terebiuthince, U. S. P. 

Turpentine " commences to boil at about 320° F. (160° C), and 
almost entirely distils below 356° F. (180° C), little or no residue 
remaining," whereas petroleum spirit, with which turpentine might 
be mixed, covers much wider limits of temperature during its dis- 
tillation. Petroleum spirit also, when the small round flame of the 
end of a piece of twine is brought near to some of the spirit in a cup, 
gives a momentary flash of flaine at a much lower temperature than 
that at which turpentine flashes. Thus tested in the specially- 
arranged flashing apparatus of the Petroleum Act, Mr. Boverton 
Redwood found that the flashing-point of turpentine was lowered 
18° by 1 per cent, of petroleum spirit. The specific gravity of oil of 
turpentine is from about 0.855 to 0.870. 

Under the influence of heat and sulphuric acid or other chemical 
agents pure oil of turpentine (C 10 H 16 ) yields many derivatives of 
considerable chemical interest. Amongst them are two optically 
inactive terpene isomers, named terebene and colophene, used for 
inhalation and as disinfectants and deodorizers. When acted on by 
gaseous hydrochloric acid the product is a white crystalline mono- 
hydrochloride, C 10 H 16 HC1. In the sunlight it slowly oxidizes, and 
hydrolizes to a crystalline body, C 10 H 18 O 2 . Bromine acts violently 
on turpentine and terpenes, resulting in dibromides, which yield 
cymene when heated, C 10 H 16 Br 2 = C 10 H 14 + 2HBr. Crystals of 
terpin hydi^ate, C 10 Hj 8 (OH) 2 ,H 2 O, also terpinol, (C 10 H 16 ) 2 ,H 2 O, are 
used therapeutically instead of terebene. 

The official Terebene, C 10 H 16 {Terebenum, U. S. P.), is a colorless, 
mobile liquid, having a somewhat aromatic odor and taste. Boils 
between 156° and 160° F. In its chemical properties it very much 
resembles oil of turpentine. 

Volatile Oils. 

The Volatile or Essential Oils exist in various "parts of plants. 
They usually are mixtures of the liquid hydrocarbons or elceoptens 
(from elaiov, elaion, oil, and bwrofiai, optomai, to see) with oxidized 
hydrocarbons, which are commonly solid or camphor-like bodies 
termed stearoptens (from creap, stear, suet), and which on cooling 
often crystallize out ; or on distilling an oil the stearopten may 
remain in the retort, being less volatile than the elaeopten. The 



414 ORGANIC CHEMISTRY. 

oils are also often associated with further oxidized bodies termed 
resins. 

The process by which volatile oils are usually obtained from 
herbs, flowers, fruits, or seeds may be imitated on the small 
scale by placing the material (bruised cloves or caraways, for 
instance) in a tubulated retort, adapting the retort to a Liebig's 
condenser, and passing steam, from a Florence flask, through a 
glass tube to the bottom of the warmed retort. The steam in 
its passage through the substance will carry the particles of 
oil over the neck of the retort into the condenser, and thence, 
liquefied and cooled, into the receiving vessel, where the oil will 
be found floating on the water. It may be collected by running 
off the distillate through a glass funnel having a stopcock in 
the neck, or by letting the water from the condenser drop into 
an old test-tube which has a small hole in the bottom, or any 
similar tube placed in a larger vessel, the water and oil being 
subsequently run off separately from the tube as from a pipette. 
The water will in most cases be the ordinary official medicated 
water of the material operated on (Aqua AnetM, Anisi, Auran- 
tii Floris, Oarui, Cinnamomi, Foeniculi, Menthse Piperitse, Men- 
thse Viridis, Pimentse, Posse (from Posse Centifolise Petala, B. P.), 
Sambuci). Volatile oils, like fixed oils, stain paper, but the 
stain of the former is not permanent, like that of the latter. 
Oils of lemon and orange are sometimes obtained by mere 
pressure of the rind of the fruit. 

The following official (U. S. P.) waters may be made by distrib- 
uting 2 parts of volatile oils over 4 parts of precipitated calcium 
phosphate, and percolating with 1000 parts of distilled water : Aquce 
Anisi, Cinnamomi, Fozniculi, Menthce Piperita?,, Mentha? Viridis. 

Aqua Aurantii Florum Fortior, U. S. P. (Aqua Aurantii Florum, 
U. S. P. 1880), is a saturated solution of volatile orange-flower oil, 
and the Aqua Aurantii Florum, U. S. P. 1890, is made by mixing 
equal volumes of the stronger orange-flower water and distilled 
water. 

The presence of alcohol in an essential oil may be detected and its 
quantity estimated by shaking with an equal bulk of pure glycerin. 
The latter dissolves the alcohol, and is augmented in volume accord- 
ing to the amount of alcohol present (Boettger). (For tests for 
alcohol see Index, " Alcohol.") 

A large number of volatile oils are employed in medicine, either 
in the pure state, in the form of saturated aqueous solution (medi- 
cated waters), solution in spirit of wine, 1 in 5 {Essentia Anisi and 
Essentia Mentha? Piperita?, B. P.), and 1 in 50 (Spiritus Cajuputi, 
Cinnamomi, Juniperi, Lavandula?, Mentha? Piperita?, Myristico?, 
Eosmarini), or as leading constituents in various barks, roots, 
leaves, etc. The strength of Spiritus Anisi, U. S. P., and Sp. Cin- 
namomi, U. S. P., is 10 of oil to 90 of deodorized alcohol. Sp. Mentha? 



VOLATILE OILS. 415 

Piperita?, U. S. P., and Sp. Menth. Viridis, U. S. P., are of similar 
strength, but also contain whatever may be extracted by the 100 
parts of the spirit from 1 part of the dried herb. Spiritus Aurantii, 
U. S. P., contains 5 of oil and 95 of alcohol; Sp. Gaultherioz, U. S. 
P., Sp. Juniperi, U. S. P., Sp. Lavandula?, U. S. P., and Sp. Myris- 
ticce, U. S. P., contain 5 of oil and 95 of alcohol ; Spiritus Limonis, 
U. S. P., is made with 10 of oil, 10 of fresh-grated lemon-peel, and 
deodorized alcohol sufficient to produce 1000 of filtered product. Per- 
fumes ("scents" or " essences," including "lavender-water" and 
" eau de Cologne") are for the most part solutions of essential oils 
in spirit of wine or spirituous infusions of materials containing 
essential oils. The following oils are, directly or indirectly, official 
in the Pharmacopoeias :* 1 . Volatile oil of Bitter Almond (vide 
Index). 2. Oil of the fruits of Ajwain or Omum, Carum Ajowan, or 
Ptychotis Jjowan (Fructus Ptychotis, P. I.) contains cymol or cymene 
(C 10 H U ) and a stearopten (Ajwainka-phul, flowers of ajwain) identi- 
cal with thymol, C 10 H 14 O. 3. Oil of Dill ( Oleum Anethi, B. P.), 
a pale, yellow, pungent, acrid liquid distilled from dill-fruit ; it con- 
tains a hydrocarbon, anethene (C 10 H 16 ), and an oxidized oil (C 10 H U 0) 
identical with the carvol of oil of caraway (Gladstone). 4. Oil of 
Aniseed ( Oleum Anisi, IT. S. P.), a colorless or pale-yellow liquid, 
of sweetish warm flavor, distilled in Europe from the anise-fruit 
(Pimpinella Anisum) (Anisum, IT. S. P.), but chiefly, in China, from 
the fruit of star-anise (Illicium Anisatum) (Illicium, U. S. P.) ; it is 
a mixture of a hydrocarbon isomeric with oil of turpentine and 
anethol, a stearopten (C, H 12 O) which crystallizes out at low tempera- 
tures. The melting-point of anethol is between 74° and 75° F. 
(Fliickiger). The congealing-point of the natural oils appears to be 
dependent on the proportion of the fluid to the solid constituent, a 
very small quantity of the former lowering the congealing- and 
melting-points very considerably. 5. Oil of Chamomile ( Oleum 
Anthemidis, B. P.), a bluish or, when old, yellow oil of character- 
istic odor and taste, distilled from chamomile-flowers (Anthemis, 
IT. S. P.). The official variety (Anthemis nobilis) yields about 0.2 per 
cent, of an oil composed of a hydrocarbon (C 10 H 16 ) and an oxidized 
portion (C 10 H 16 O 2 ), which, heated with potash, gives potassium 
angelate (KC 5 H 7 2 ), whence is obtained angelic acid (HC 5 H 7 2 ). 
According to Demarcay, Kopp, and Kobig, the oil is a mixture of 
the angelates of butyl and amyl and similar bodies. Naudin has 
also obtained from chamomile anthemen, a hydrocarbon crystallizing 
in needles. The flowers of another variety (Matricaria Chamomilla) 
[Matricaria, IT. S. P.) contain a stearopten (C 10 H lfi O) having the 
composition of laurel-camphor. 6. Oil of Horse-radish root (Armo- 
racice Radix, B. P.) is, according to Hofmann, butyl or tetryl sul- 
phocyanate (C 4 H 9 CNS) : it is the chief active ingredient of Spiritus 
Armoracia; Compositus, B. P. 7. Oil of Sweet- Orange peel (Aurantii 
Dulcis Cortex, U. S. P.) and oil of Bitter-Orange rind (Aurantii 
Amari Cortex, U. S. P. ; Oleum Aurantii Corticis, U. S. P.), the 

* The student is not expected to remember, but to understand, all that 
follows respecting the volatile oils. 



416 ORGANIC CHEMISTRY. 

former the flavoring constituent of the official syrup of the peel 
{Syrupus Aurantii, U. S. P.) and the oils of various species of 
Citrus — namely, 8, lemon {Oleum Limonis, U. S. P.), from lemon- 
peel {Limonis Cortex, U. S. P.); 9, lime, 10, bergamot {Oleum 
Bergamottce, U. S. P.), 11, citron and a variety of citron termed 
cedra — resemble each other in composition, all containing hesperidene, 
a hydrocarbon (C 15 H 34 ), and a small quantity of oxidized hydrocar- 
bons [C 10 H 10 O 5 ,C 15 H 16 O, and (Wright and Piesse) C 20 H 30 O 3 ], etc. 
Tilden states that lemon oil distilled from the fresh peel consists 
chiefly of a terpene, C 10 H 16 , boiling at 176° C, with small quantities 
of a terpene boiling below 160°, and a hydrous terpene, the odor of 
the oil being due to the mixture. Oil of bergamot appears to owe 
its fragrance to 40 or 50 per cent, of linalool acetate, C 10 H 1Y C 2 H 3 O 2 . 
It also contains a stearopten, bercapten, C 12 H 8 4 . Expressed lime 
essence contains a soft resin. 12. Oleum Aurantii Florum, U. S. P., 
oil of Neroli or Orange-flower, the aqueous solution of which is 
official in the forms of water {Aqua Aurantii Florum Fortior, U. S. P.) 
and syrup {Syrupus Aurantii Florum, U. S. P.), contains a fragrant 
hydrocarbon (C 10 H 16 ), colorless when fresh, but becoming red on 
exposure to light, and an inodorous oxidized hydrocarbon. Strong 
acids, especially nitric, attack the oil in orange-flower water, color- 
ing the fluid of a rose tint. 13. Oil of Petit Grain, distilled 
from the leaves and shoots of the orange tree, consists chiefly of 
aurantiol acetate, C 10 H 17 C 2 H 3 O 2 . 14. The leaves of Boldo {Peumus 
Boldus). a Chilian shrub (tonic and hepatic), yield 2 per cent, of 
essential oil (and, according to Bourgon and Verne, an alkaloid, 
boldine). 15. Oil of Buchu-leaves {Buchu, U. S. P.) consists 
chiefly of a fluid oil, C 10 H 18 O, holding in solution a crystalline 
stearopten, diosphenol, (Ci 4 H 22 3 , Fluckiger ; C 10 H 16 O 2 , Spica, 
Shimoyana also). 16. Oil of Cannabis indica, see p. 423. 

17. Oil of (the lesser) Cardamoms, from the seeds of the capsules 
{Cardamomum, U. S. P.), is chiefly a hydrocarbon (C 10 H 16 ) 
isomeric with oil of turpentine (terpilene and probably limonene) 
and a camphor resembling turpentine-camphor (C 10 H 16 3H 2 O). 

18. Oil of Cajuput {Oleum Cajuputi, U. S. P.) is a mobile bluish 
liquid, consisting of hydrous cajuputene or cajuputol (C 10 H 16 ,H 2 O) ; 
cajuputene, C 10 H 16 ; cineol, C 10 H 17 OH ; a sesquiterpene, Ci 5 H 24 5 
as well as butyric, valeric, and benzoic aldehydes. The latter, 
repeatedly distilled from phosphoric anhydride, yields caju- 
putene itself (C 10 H 16 ), which has the odor of hyacinths. Fresh 
cajuput oil has a green hue, which is perhaps transient, for the 
color of the oil of trade is due to copper (Guibourt and Histed) : 
certainly the green coloring-matter of pure cajuput oil is organic 
and either oily or chlorophylloid. 19. Oil of Caraway-fruit {Carum, 
U. S. P., Oleum Carui, B. P., Oleum Cari, U. S. P.) is a mixture of 
carvene (C 15 H 24 ) and carvol (C 10 H u O). 20. Oil of Cloves {Caryo- 
phyllus, U. S. P., Oleum Caryophylli, U. S. P.) and of Pimento or 
Pimenta, U. S. P., or Allspice {Oleum Pimentce, TJ. S. P.), both 
heavier than water, contain a liquid hydrocarbon (C 15 H 24 ), eugenol 
(C 10 H 12 O 2 ), a solid body, eugenin, isomeric with the eugenic acid, a 
second crystalline substance, caryophyllin (C 10 H 16 O), isomeric with 



VOLATILE OILS. 417 

common camphor, and a salicylic compound. 21. Oil of Cascarilla- 
bark (Cascarillce, U. S. P.) has not been fully examined. 22. Oil 
of Cinnamon-bark (Cinnamomum Cassia, U. S. P.) and of Cassia- 
bark is mostly cinnamic aldehyde (C 8 H 7 COH). Boiled with nitric 
acid, it furnishes benzoic aldehyde (C 6 H 5 COH) and benzoic acid 
(C 6 H 5 COOH) ; with chloride of lime it yields calcium benzoate 
(C 6 H 5 COO) 2 Ca, and with caustic potash gives potassium cinnamate 
(C 8 H 7 COOK). The specific gravity of oil of Ceylon cinnamon is 
about 1.040, and of Chinese cinnamon (oil of cassia) about 1.060. 
Both are termed Oleum Cinnamomi in U. S. P. 23. Oil of Citron- 
ella, a grass oil, from Andropogon nardos, is chiefly composed of 
citronellol (C 10 H 16 O and C 10 H 18 O, Wright), probably isomeric with 
the absinthol from the Artemisice Absinthium or wormwood (Absin- 
thium, U. S. P.) (Gladstone). Kremer also obtains heptoic aldehyde 
(C 7 H u O), a terpene (C 10 H 16 ), etc. 24. Oil of Copaiva {Oleum Co- 
paibas, U. S. P.), and, 25, of Cubebs {Oleum Cubebos, U. S. P.), are 
hydrocarbons having the formula C 15 H 24 . This cubebene is some- 
times associated with a camphor, hydrous cubebene (C 15 H 24 ,H 2 0). 
Oil of cubebs also contains a small quantity of a terpene (C 10 H 16 ). 
26. Oil of Coriander ( Oleum Coriandrum, \J. S. P.) seems to have 
the composition of hydrous oil of turpentine (C 10 H 16 ,H 2 O). 27. The 
fruits of Cumin, or Cummin {Cuminum Cyminum), an ingredient of 
many curry-powders, contain about 3 per cent., and those of Water 
Hemlock or Cowbane {Cicuta virosa) about 1^ per cent., of an essen- 
tial oil composed of cymol or cymene (C 10 H U ) and cumic aldehyde 
(CgHjjCOH). The latter is an aldehyde readily uniting with alka- 
line bisulphites and by oxidation yielding cuminic acid (C 9 H n COOH). 
Cymol also occurs in Garden Thyme {Thymus vulgaris). '21a. The 
fresh flowering herb of Erigeron canadense, or Canadian fleabane, 
yields an essential oil {Oleum Erigerontis, U. S. P.). 28. The fresh 
leaves of various species of Eucalyptus (E. globulus, E. oleosa or 
cneorifolia-, E. dumosa, and other ''mallee" — that is, "scrub" or 
shrub-like eucalypts) furnish about 1 per cent, of the essential Oil 
of Eucalyptus {Oleum Eucalypti, U. S. P.). The more volatile por- 
tion of this oil consists partly of cymene and three terpenes — namely, 
pinene, limonene, and, especially in E. amygdalina, phellandrene 
(p. 412). The latter is more readily alterable than other terpenes, 
and is characterized by yielding a crystalline mass with nitrous 
anhydride. Oxidized bodies also are present, C 10 H u O, C 10 H 16 O, and 
40 to 50 per cent, of an oil (or, when cooled, a camphor) having the 
same composition as cajuputol, and as the chief constituent of worm- 
seed oil — namely, eucalyptol, C 10 H 18 O or C 10 H 16 ,H 2 O ; boiling at about 
174° C, freezing at about 0° C., and having a specific gravity of 
about 0.927. It is not yet known satisfactorily to which of the 
constituents of eucalyptus oil its medicinal efficacy is due. The 
sp. gr. of the oils varies greatly — namely, 0.030 to 0.040 above or 
below 0.900. The official density is 0.915 to 0.925. Different species 
of eucalyptus may yield oils differing in specific gravity, flavor, and 
odor. E. maculata, var. citriodora, contains an aldehyde or ketone 
similar to that of citronella. Like the turpentines, the eucalyptus 
oils are good solvents of resins. Voiry states that eucalyptol is 



418 ORGANIC CHEMISTRY. 

present also in the oil of Lavandula spica, oil of spike or "foreign" 
oil of lavender. Red gum (Eucalypti Gummi, B. P.) is from the 
E. rostrata and other species, and is used solely for its astringent 
properties. 29. Elecampane-root (Inula Helenium) (Inula, U. S. P.) 
by distillation with water yields solid volatile helenin (C 6 H 8 0), a 
camphor-oil or inulol (C 10 H 16 O), and inulic anhydride or lactone 
(C 15 H 20 O 2 ), as well as, according to Marpmann, crystals of alantic 
acid (C 15 H 22 3 ) and fluid alantol (C 20 H 32 O), each more powerfully 
antiseptic than helenin. 30. Oleum Foeniculi, U. S. P., oil of Fen- 
nel-fruit (Foeniculum, U. S. P.), differs in odor, but contains the same 
proximate constituents as oil of anise. 31. Oil of Geranium, or 
Ginger Grass oil, from Andropogon schoenanthus and various species 
of Pelargonium, contains geraniol (C 10 H 18 O). 32. Grains of Para- 
dise (Amomum melegueta), Guinea Grains or Melegueta Pepper, 
Semina Cardamomi Majoris, contain essential oil (C 10 H 16 and 
C 10 H 16 O) and a highly pungent principle, termed by Thresh para- 
dol, C 9 H u 2 , isomeric with capsaicin of the same chemist. 32a. Oil 
of American Pennyroyal (Hedeoma, U. S. P.), "the leaves and tops 
of Hedeoma pulegioides," contains hedeomol (C 10 H 18 O), and yields 
isoheptoic acid (C 7 H u 2 ) and other substances (Kremer). 33. Oil 
of luniper (Oleum Juniperi, U. S. P.), the active constituent of 
juniper tops and berries, contains a hydrocarbon (C 10 H 16 ) which 
by contact with water yields a white crystalline hydrous compound 
(C 10 H 16 ,H 2 O) and a polymeric hydrocarbon (C 20 H 32 ). 34. Oil of 
Lavender (Oleum Lavandula?, B. P.) is distilled from the flowers 
of Lavandula vera, and is the same as Oil of Lavender-fowers 
( Oleum Lavandula Florum, U. S. P.) ; it has not been satisfactorily 
examined. 34a. Oil of Myrcia (Oleum Myrcice, U. S. P.), oil of bay 
or bayberry oil (sp. gr. about 1.040), is obtained from the leaves of 
Myrcia acris. 35. Oil or butter or camphor of Orris (Iris Flor en- 
Una) is a soft solid lighter than water. Fliickiger and Hanbury 
found it to be chiefly myristic acid associated with a little essential 
oil. 36. Oil of Peppermint (Oleum Mentha? Piperita?, U. S. P.) con- 
sists of a hydrocarbon, menthene (C 10 H 18 ), different from that of 
most volatile oils, depositing crystalline peppermint camphor, known 
as menthol, C 10 H 18 ,H 2 O, when exposed to low temperatures. It is 
official (Menthol, U. S. P., also Emplastrum Menthol, B. P.), and has 
the following characters : "In colorless acicular crystals, usually 
more or less moist from adhering oil, or in fused crystalline masses. 
Its melting-point should not exceed 110° F. (43.3° C). It has the 
odor and flavor of peppermint, producing warmth on the tongue, 
or, if air be inhaled, a sensation of coolness. It is sparingly soluble 
in water and readily soluble in rectified spirit, the solutions having 
a neutral reaction. Boiled with sulphuric acid diluted with half its 
volume of water, menthol acquires an indigo-blue or ultramarine 
color, the acid becoming brown. It should be entirely dissipated 
by the heat of a water-bath." — B. P. Its alcoholic solution rotates 
a ray of polarized light to the left. " If a few crystals of menthol 
be dissolved in 1 cc. of glacial acetic acid, and then 3 drops of sul- 
phuric acid and 1 drop of nitric acid added, no green color should 
be produced (absence of thymol)." — U. S. P. It is also yielded by 






VOLATILE OILS. 419 

the oil of Mentha arvenis (vars. piperasceus and glabrata). 37. Oil of 
Spearmint ( Oleum Menthce Viridis, U. S. P.), the common mint of the 
kitchen garden, contains a liquid having the formula C 10 H 20 O or 
C 10 H 18 ,H 2 O ; also, according to Gladstone, an oil (C 10 H u O) isomeric with 
carvol. 38. Oil of Pennyroyal {Mentha Pulegium) contains, according 
to Kane, C 10 H 16 O (pulezone ; Plaisner). 38a. The leaves and tops of 
Melissa officinalis or Balm (Melissa, U. S. P.) yield a volatile oil contain- 
ing a camphor. 39. Oil of Nutmeg ( Oleum Myristicce, B. P. and U. S. P.) 
is composed of a hydrocarbon, myristicene (C 10 H 16 ), and myristicol 
(C 10 H ]6 O), and cymene (C ]0 H W ) (Gladstone). Mace (Marts, U. S. P.), 
the arillus or net-like envelope of the nutmeg, appears to yield sim- 
ilar bodies, and also myristicin, C 12 H i4 3 (Semmler). 40. Oil or 
Otto or Attar of Cabbage-rose Petals (Rosce Centifoliai, IT. S. P., 
Oleum Rosaz, U. S. P.) gives the fragrance to rose-water (Aqua Rosoz 
and Aqua Rosoz Fortior, U. S. P.). It resembles most other volatile 
oils in being composed of a hydrocarbon and an oxidized portion, 
but differs from all in this respect, that the hydrocarbon is solid and 
is destitute of odor, while the oxygenated constituent is liquid and 
the source of the perfume. According to Fliickiger, the solid hydro- 
carbon (C 18 H 16 ) yields succinic acid as the chief product of its oxida- 
tion by nitric acid, and in other respects affords evidence of belong- 
ing to the paraffin series of fats. 41. Oil of Rosemary-tops (Oleum 
Rosmarini, U. S. P.) exists in the plant to the extent of from 1| to 
3 parts per 1000. It chiefly consists of a hydrocarbon (C 10 H ]6 ) re- 
sembling that from myrtle, Myrtus communis, but also contains 
camphor (C 10 H 16 O) and borneol (C 13 H 18 0) in variable proportions. 
42. Oil of Rue (Oleum Rutce, B. P.) contains a small quantity of 
hydrocarbon (C 10 H 16 ) with some rutic aldehyde (C 10 H 20 O), and 
methyl-nonyl ketone, C u H 22 or CH 3 — CO — C 9 H 19 . Gorup-Besanez 
and Grimm have obtained oil of rue (C u H 22 0) artificially as one 
of the products of the destructive distillation of calcium acetate 
and caprate. (See Ketones.) According to Greville Williams, it 
is chiefly euodic aldehyde (C u H 22 0), some lauric aldehyde (C 12 H 24 0) 
also being present. 43. Oil of Sage (Salvia, U. S. P.) contains about 
40 per cent, of salviol, C 10 H 16 O ; about 20 per cent, of two C 10 H 16 
hydrocarbons, boiling at 156° and 167° C. respectively ; about 10 
per cent, of a camphor, C ]0 H 16 O ; and about 10 per cent, of cedrene, 
C 15 H 24 (Muir). 44. Oil of Savin (Oleum Sabince, U. S. P.) obtained 
from the tops of Juniperus Sabina or Savina (Sabina, U. S. P.), 
contains several hydrocarbons, but none isomeric with oil of tur- 
pentine (Tilden). 45. Oil of Elder-floivers (Sambucus, U. S. P.) 
occurs in very small quantity ; it has a butyraceous consistence ; it 
contains a hydrocarbon, sambucene (C 10 H 16 ), and probably a cam- 
phor. 46. Oil of Sandal-wood (Oleum Santali, U. S. P.) or Oil of 
Santal is composed (Chapoteaut) of two bodies : mostly of a sub- 
stance having a formula C 15 H 24 (boiling at 572° F.), and a small 
quantity of a substance having the formula C 15 H 26 (boiling at 
600° F.). It occurs to the extent of about 2 J per cent, in the 
fragrant white or yellow sandal-wood of India, Santalum album, a 
small tree of the natural order Santalacese, and not to be confounded 
with the Pterocarpus santalinus, a tree of the natural order Legu- 



420 ORGANIC CHEMISTRY. 

minosae and furnishing the inodorous Red Sandal- wood or Red 
Sander's Wood or Barwood of the dyer. 47. Oil of Sassafras-root 
(Oleum Sassafras, U. S. P.) (Sassafras, U. S. P.), sp. gr. 1.094, con- 
tains nine-tenths of its weight of safrol or sassafrol, C 10 H 10 O 2 , also 
eugenol and a small quantity of a terpene. Sassafras camphor, 
C 10 H 10 O 2 , is deposited when the oil is exposed to a low temperature. 
48. Oil of Mustard (Oleum Sinapis Volatile, U. S. P.) is allyl sul- 
phocyanate. (See Index.) If contaminated with alcohol, its sp. gr. 
is below 1.015. 49. Oil of Sweet Flag (Acorus calamus) contains 
the hydrocarbon C 10 H 16 . The rhizome (Calamus, U. S. P.) also con- 
tains acorin, C 36 H 60 O 6 , a bitter glucoside, and an alkaloid, calamine. 
50. Oil of common garden Thyme (Thymus vulgaris, Oleum Thymi, 
U. S. P.) is composed of cymene or cymol (C 10 H U ), thymene (C 10 H 16 ), 
and thymol (C 10 H u O). Thymol, U. S. P., crystallizes out when oil 
of thyme or of ptychotis, etc. is kept at a low temperature for a 
day or two. It may also be obtained by shaking the oils with 
caustic alkali, and treating the separated alkaline liquid with an 
acid. It may be purified by distillation or by crystallization from 
alcohol. It would seem that as an antiseptic thymol is far stronger 
than carbolic acid. 51. Oil of Turmeric (Curcuma longa) is said by 
Jackson and Menke to be chiefly an alcohol having the formula 
C 19 H 27 OH. They name it turmerol. It is a light yellow volatile 
oil, having the sp. gr. 0.902. It is to this oil that turmeric (hence 
curry-powder partly) owes its flavor and odor. 52. Oil of Valerian- 
root ( Valerianae, U. S. P.) is a mixture of a hydrocarbon, valerene 
or borneene (C 10 H 16 ), valerol (C 6 H 10 O), and (Gersek) 10 per cent, of 
borneol valerianate. Valerol slowly oxidizes to valerianic acid, 
known by its smell. A similar change occurs at once if oil of 
valerian be allowed to fall, drop by drop, on heated caustic potash : 
C 6 H 10 O + 3KHO + H 2 = K 2 C0 3 + C 4 H 9 COOK + 3H 2 . By the 
action of sulphuric acid on the potassium valerianate thus produced 
valerianic acid is obtained. 53. Oil of Verbena, Lemon-grass Oil, or 
Indian Melissa Oil, is obtained from Andropogon citratus (Oleum 
Andropogi Citrati, P. I.). 54. Oil of Ginger (Zingiber, B. P.) is, 
according to Thresh, a complex mixture of hydrocarbons and their 
oxidation-products ; cymene (C 10 H 14 ) is present, a terpene, aldehydes, 
and ethereal salts. (For an analysis of ginger by Thresh, and for 
papers on " Soluble Essence of Ginger," see the Pharmaceutical 
Journal for August 30 and September 6, 1879, and March 4, 1882.) 
55. American Wormseed ( Chenopodium, U. S. P.) contains a volatile 
oil (Oleum Chenopodii, U. S. P. ; p. 417). 

Caoutchouc (or India-rubber) and Gutta Percha. 

Caoutchouc is the hardened juice of Dichopsis Gutta, Hevea 
(Siphonia) Brasiliensis, Castilloa elastica, Urceola elastica, Ficus 
elastica, and other plants. Heated moderately with sulphur, it 
takes up 2 or 3 per cent. , and forms vulcanized india-rubber ; at a 
higher temperature a hard horny product, termed ebonite or vulcanite, 
results. Gutta Percha ( Gutta Percha, B. P.) is the concrete drop or 
juice of the percha (Malay) tree, the Isonandra gutta, and of other 



CAMPHORS. 421 

Sapotaceous plants. White gutta percha is obtained by precipitating 
a solution of ordinary gutta percha in chloroform by alcohol, wash- 
ing the precipitate with alcohol, and finally boiling in water and 
moulding into the desired form while still hot. The official solution 
of gutta percha {Liquor Gutta Percha, B. P.) is made by digesting 
thin slices of gutta percha in 12 parts by weight of chloroform, and 
then " fining" by shaking with 1 part of lead carbonate and setting 
aside till the fluid is clear. 

These two elastic substances, in the pure state, are hydrocarbons 
(icC 5 HJ, usually slightly oxidized. • When caoutchouc is distilled a 
terpene, C 10 H 16 , called caoutchin, is obtained. 

Official india-rubber (Elastica, U. S. P.) is " the prepared milk- 
juice of various species of Hevea(nat. ord. Euphorbiacese), known in 
commerce as Para rubber." It melts at about 125° C. 

Camphors. 

In addition to the stearoptens or camphors already mentioned as 
being contained in or formed from volatile oils, there is one that is a 
common article of trade. It is obtained from the wood of Camphora 
qfficinarum, or camphor-laurel, in Japan (termed, in Europe, Dutch 
camphor, because imported by the Dutch, and in China known as 
Formosa camphor), by a rough process of distillation with water, and 
is purified by resublimation [Camphora, U. S. P.). The formula of 
laurel-camphor is C 10 H 16 O. Sp. gr. 0.990 to 0.995; melting-point, 
175° C. ; boiling-point, 205° C. Bromine heated with camphor 
gives monobrom-camphor (C 10 H 15 BrO) and hydrobromic acid. Mono- 
brom-camphor is camphor in each molecule of which an atom of 
hydrogen has been displaced by one of bromine. Recrystallized, it 
occurs in white prisms. The essential oil, from which doubtless 
camphor is derived by oxidation, is easily obtained from the wood, 
and is occasionally met with in commerce under the name of liquid 
camphor or camphor oil. It contains hydrocarbons resembling tere- 
binthene and citrene, and hydrous camphor (C 10 H ]6 O,H 2 O) as well as 
camphor. By exposure to air it becomes oxidized and deposits com- 
mon camphor. Camphor distilled with phosphoric anhydride yields 
cymene, C 10 H U . There is another kind of camphor, borneol, in 
European markets, less common than laurel-camphor, but highly 
esteemed by the Chinese ; it is obtained from the Drijobalanops 
aromatica, and denominated Sumatra or Borneo camphor. It differs 
slightly from laurel-camphor in containing more hydrogen, its for- 
mula being C 10 H ]8 O. It may be obtained by acting on camphor with 
hydrogen, the camphor being dissolved in some inert liquid, such as 
toluene, and sodium added ; the sodium forms a compound, C 10 H 15 ONa, 
Avhile the hydrogen thus liberated acts on another portion of the 
camphor, forming borneol, C 10 H n (OH) — abetter result being obtained 
if absolute alcohol is used instead of toluene (Jackson and Menke). 
It is accompanied in the tree by a volatile oil (C 10 H 16 ) isomeric with 
oil of turpentine. This oil, bomeene, is also occasionally met with 
in trade under the name of liquid camphor or camphor oil, but 
differs from laurel-camphor oil in not depositing crystals on exposure 
to air. 

19 



422 ORGANIC CHEMISTRY. 

The constitution of the camphors is still somewhat doubtful. 
Camphor is soluble to a slight extent in water (40 grains per gallon, 
Pooley). The official camphor-water (Aquas Camphor ce, U. S. P.), 
or camphor mixture, is such a solution. 

Common camphor and many other of the camphors, oily hydro- 
carbons, and oxidized hydrocarbons yield camphoric acid, CgH u - 
(COOH 2 ), and camphoronic acid, C 7 H 9 (OH)(COOH) 2 , when attacked 
by oxidizing agents. Such reactions indicate natural relationships. 
Camphoric acid is a good antiseptic. 

Cantharidin (C 10 H 12 O 4 ), the active blistering principle of can- 
tharides (Cantharis, U. 8. P.) and other vesicating insects (such as 
Mylabris cichorii or Telini Fly, P. I., common in India), has most 
of the properties of a camphor or a stearopten. It slowly crystal- 
lizes, from an alcoholic tincture of the beetles, in fusible, volatile, 
micaceous plates. The following process for the extraction of can- 
tharidin is by Fumouze : Powdered cantharides are macerated with 
chloroform for twenty-four hours ; and this treatment is repeated 
twice with fresh quantities of solvent, the residue having been well 
squeezed each time. The collected solutions are then distilled, and 
the dark-green residue treated with carbon disulphide, which dis- 
solves fatty, resinous, and other matters and precipitates the canthar- 
idin. The precipitate is placed on a filter, washed with carbon 
disulphide, and recrystallized from chloroform. The same process, 
omitting the final recrystallization, may be used for the quantitative 
estimation of cantharidin in cantharides. The average quantity 
found is from 4 to 5, or occasionally 10 or even 12, parts in 1000. 
Cantharidin is readily soluble in warm glacial acetic acid (Tichborne), 
and still more readily in acetic ether or chloroform. Cantharides 
from which the fat has been removed by petroleum ether yield their 
cantharidin with great facility. 

Massing and Dragendorff consider cantharidin to be an anhydride, 
and that with the elements of water it forms cantharidic acid 
(II 2 C 10 Hj 2 O 5 ). Piccard gives the vapor-density of cantharidin as 
about 6.5, and its formula C 10 H 12 O 4 . Homolka assigns to it the 
formula C 8 H 13 OyCOCOOIi. 

Resins, Oleo-Resins, Gum-Resins. 

Resins seem to be the oxidized products of terpenes and the allied 
hydrocarbons ; they occur in plants, generally in association with 
volatile oils. They closely resemble camphors and stearoptens, but 
are not volatile, and differ from oils and fats mainly in being solid 
and brittle. For convenience they are classified as resins, oleo- 
resins, and gum-resins, the distinctions being founded as much on 
physical as on chemical properties. 

Oleo-resins are mixtures of a resin and a volatile oil. 

Gum-resins are mixtures of a resin or oleo-resin and gum. 

Balsams are commonly described as resins or oleo-resins which 
yield benzoic and cinnamic acids ; they are benzoin (Benzoinum, 
U. S. P.), balsam of Peru (Balsamum Feruvianum, U. S. P.), balsam 
of Tolu (Balsamum Tolutanum, U. S. P.), and storax, and are 
treated of under the respective acids. 



RESINS. 423 

Some oleo-resins, containing neither of the above acids, are often 
termed balsams (e.g. balsam of copaiva and Canada balsam) ; these 
will be treated under the head of Oleo-resins. 

A physico-chemical method for the identification of the chief 
resins, gum-resins, and balsams will be found in the Pharmaceutical 
Journal for November 17, 1877. 

Resins appear to be somewhat antiseptic. Beer is said never to 
turn sour in casks lined with Burgundy pitch. The resin of hops 
has perhaps a similar effect in retarding oxidation of alcohol. 

Resins.* — 1. Resin, rosin, or colophony (Resina, U. S. P.) is the 
type of this class. Its source is the oleo-resin or true turpentine of 
the conifers, a body which by distillation yields spirit of turpentine 
and a residuum of rosin. "Brown" and "white" rosin are met 
with in trade. The former is the residue of American, the latter of 
Bordeaux, turpentine (from Pinus Abies, etc. and Pinus maritima 
respectively). The chief constituents of brown resin are pinic acid 
(HC 20 H 29 O 2 ) and sylvic acid, identical in composition, but differing 
in properties (vide Isomerism), the former being soluble and the 
latter insoluble in cold spirit of wine. White resin or "galipot" 
is chiefly pimaric acid, also isomeric with pinic acid. Pinic acid, 
cautiously heated, yields colophonic or colopholic acid. Rosin by 
destructive distillation yields resin oil, the first portion being " pale," 
the next " blue," and the third " green resin oil." Mixed with 
other oils, they are used for lubricating purposes and in the manu- 
facture of printing ink. Among the products of the destructive 
distillation of resin Tichborne has found " colophonic hydrate' 1 '' 
(C 10 H 22 O 3 ,H 2 O), a white inodorous crystalline substance, and by 
depriving this of water has obtained white crystalline colophonine 
(C 10 H 22 O 3 ). Resin is soluble in oil of turpentine. Contact with 
sulphuric acid immediately colors it strongly red. It is a con- 
stituent of four of the fourteen plasters (Emplastra) of the U. S. 
Pharmacopoeia. 2. Arnicin (C 20 H 30 O 4 ), the chief acrid and one of 
the active principles of arnica (Arnicoz Flores, IT. S. P. ; Arnica 
Rhizoma, B. P.), is a resin, and, probably, a glucoside. 3. Canna- 
bin, said to be the active principle of Indian Hemp (Cannabis Indica, 
U. S. P.), was obtained in 1846 by T. and H. Smith, and is a resin. 
Personne in 1857 isolated a volatile oil, also said to possess much 
medicinal activity, consisting of cannabene (C 18 H 20 ) and a solid crys- 
talline, " cannabene hydride" (C 18 H 22 ). A sesquiterpene (C 15 H 24 ) is 
also said to be present. Preobraschensky has stated, and since 
reasserted, that the active principle is nicotine. Kennedy searched 
for nicotine by two methods, but found none. Hay found an alka- 
loid, tetano-cannabine ; Siebold and Bradbury, also II. F. Smith, an 
alkaloid termed cannabinine. Warden and Waddell, after careful 
investigations, consider that the active principle of the plant has 
yet to be isolated. Jahns finds choline present. The native names 
of Indian hemp — that is, of the cultivated " dried flowering or fruit- 
ing tops of the female plants of Cannabis sativa 1 " 1 — are ganga and 

* The student is not expected to remember, but to understand, all that 
follows respecting the resins. 



424 OEGANIC CHEMISTRY. 

gunjah. It is chiefly grown in Bengal. Guaza is. the name of the 
Bombay product, which includes the wild plant. Both are used for 
smoking, and form the equivalent of the tobacco luxury of Western 
nations. Bhang, or sidee, consists of the dried leaves, fruit, and 
twigs of the wild plant. Its infusion is drunk, as tea is in Europe 
and elsewhere. Hashish, made from bhang, corresponds to our 
Extr actum Cannabis Indices,, B. P. C haras or churras is a resinous 
exudation of the plant, and is also used for smoking. All these 
preparations are stimulating and narcotic. 4. Capsicum-fruit con- 
tains a resin (p. 425). 5. Castorin, a resinous matter, is the name 
given to the chief constituent of Castor (Castoreum, B. P.), the dried 
preputial follicles and included secretion of the beaver (Castor 
Fibre). 6. Copal. — The best copal is the exuded resin of trees of 
extinct forests, and is found beneath the surface of the ground in 
the neighborhood of existing trees. It appears to be a mixture of 
acids, but its character is still obscure. 6a. Doundake'-bark, an 
African febrifuge, from Sarcocephalus escidentus, owes its activity 
to resinoid substances, according to Heckel and SchlagdenhaufFen. 
7. Dragon's Blood, a crimson-red resin found as an exudation on 
the mature fruits of a rotang or rattan palm (Calamus draco). It 
consists of resins having the probable formula C 20 H 24 O 4 and C 20 H 20 O 4 
(Johnston). 8. Ergotin is a very active resinoid constituent of 
Ergot (Ergota, U. S. P.), or the sclerotium (compact mycelium or 
spawn) of Claviceps purpurea, produced within the pales and repla- 
cing the grain of the common rye, Secale cereale. According to 
Wenzell, ergot contains two alkaloids, ecboline and ergotine, to the 
former of which, he says, the activity of ergot is due. Blumberg 
considers these alkaloids to be identical. Tanret states that an 
unstable alkaloid termed ergotinine occurs in ergot to the extent of 
1 per 1000, and that it is accompanied by a camphor ; also ergosterin, 
C 26 H 40 O,H 2 O, resembling cholesterin. Dragendorffand Podwissotzki 
assert that ergot owes most of its activity to sclerotic or sclerotinic 
acid, present to the extent of about 4 per cent. Recent investiga- 
tions seem to show that cornutine is an active alkaloid of ergot, 
associated with ergotinic and sphacelinic acids, picrosclerotine and 
ergotinine. The activity really seems to be due to a combination 
of alkaloids and acids, and not to any one constituent, as no princi- 
ple representing the full activity of ergot has been extracted. The 
same may be said of a similar therapeutical agent, the root-bark of 
Gossypium herbaceum (Gossypii Badicis Cortex, U. S. P.), the activity 
of which appears to reside in a red resin. Ergot also contains 
choline, which by decomposition may yield trimethylamine. " Er- 
gotin' 1 '' (Ergotinum, B. P.) is an alcoholic extract of an aqueous 
extract of ergot. 9. Guaiacum Besin is a mixture of substances. 
(See Index.) 10. Jalap Besin. (See Index.) 11. Kousso (Cusso, 
U. S. P., formerly Bray era) yields yellow crystals of a resinoid body 
readily soluble in alkaline liquids, kosin or koussin (C 31 H 38 O 10 ). It 
is, perhaps, an anhydride. 12. Mastic (Mastiche, U. S. P.) is a 
resinous exudation obtained by incision from the stem of the mastic 
or lentisk tree. Nearly nine-tenths of mastic is mastichic acid 
(C 20 H 32 O 3 ), a resin soluble in alcohol} the remainder consists of 



OLEO-RESINS. 425 

masticin (C 20 H 32 O), a tenacious, elastic resin, and a terpene having 
the formula C 10 H 16 . 13. Mezereon (Mezereum, U. S. P.), the dried 
bark of Daphne Mezereum, mezereon, and Daphne laureola, spurge 
laurel, owes its acridity to a resin. 14. Pepper contains resin. 
(See Index.) 15. Burgundy Pitch (Pix Burgundica, U. S. P.) is 
the melted and strained exudation from the stem of the spruce fir, 
Abies excelsa. The term Burgundy is a misnomer, the resin never 
having been collected at or near Burgundy — Finland, and to a 
smaller extent Baden and Austria, being the countries whence it is 
derived. Its constituents closely resemble those of common resin. 
It is often adulterated and imitated by a mixture of resin with palm 
oil, water, etc., from which it may be readily distinguished by its 
duller yellow color, highly aromatic odor, greater solubility in alco- 
hol, and almost complete solubility in twice its weight of glacial 
acetic acid (Hanbury). 16. Podophyllum Resin. — In preparing the 
resin of podophyllum or may-apple (Resina Podophylli, U. S. P.), 
an alcoholic extract of the rhizome and rootlets (Podophyllum, U. S. 
P.) is poured into cold water ; the resin is then deposited. This 
resin is the chief active principle of podophyllum-root. According 
to Guareschi, podophyllin contains a glucoside resembling con- 
volvulin. Podwissotzki has extracted from podophyllum a little 
crystalline coloring matter, fat, a bitter crystalline acid, a bitter 
crystalline neutral principle, and an amorphous acid resin. Kiir- 
sten states that the latter yields a crystalline active substance, 
podophyllotoxin, C 23 H 24 9 . 17. Pyrethrin is the name of the acrid 
resinous active principle of the root of Anacylus pyrethrum, or 
Pellitory-root (Pyrethrum, U. S. P.). According to Buckheim, the 
action of alkalies breaks it up into piperidine and pyrethric acid. 
The crystalline poisonous principle obtained by Bellesme from 
Pyrethrum carneum, the powder of which (and P. roseum, and 
especially P. cineraricefolium, or Dalmatian insect powder) is the 
well-known " insecticide," has not yet been analyzed. 18. The 
resins of rhubarb have already been alluded to in connection with 
Chrysophanic Acid. 19. Rottlerin, C u H 10 O3 (mallotoxin, C n H 10 O 3 , 
Perkin), is the name given by Anderson to a crystalline resin from 
kamala (Kamala, U. S. P.), the minute glands that cover the cap- 
sules of Rottlera tinctoria : to this and, apparently, allied resins 
(isorottlerin, A. G. Perkin) kamala owes its activity as an anthel- 
mintic. 

Oleo-resins. — 1. " Capsicin," a term suggestive of a definite 
chemical substance, is a name somewhat unhappily accorded to an 
indefinite substance, an oleo-resin, obtained by digesting the alco- 
holic extract of capsicum-fruit (Capsicum, U. S. P.) in ether and 
evaporating the clear ethereal fluid to dryness. Besides volatile oil 
and resin, capsicum-fruits contain much fatty matter, which Thresh 
states is chiefly free palmitic acid. (See also Capsicine and Cap- 
saicin, in Index.) 2. Copaiva (Copaiba, U. S. P.) is a mixture of 
essential oil (C 15 H 24 ), copaivaol, C 20 H 32 (Strauss), with 2 or more 
per cent, of brown soft resin, and 30 to 60 of a yellow dark crystal- 
line resin consisting mostly of copaivic acid (C 20 H 32 O 2 ) with oxyco- 
paivic acid, C 20 H 28 O 3 (Fuhling), and metacopaivic acid, C 22 II 34 4 



426 ORGANIC CHEMISTRY. 

(Strauss). Copaiva, containing about equal parts of this acid and 
of the oil, heated with a fourth of its weight of the official magne- 
sium carbonate, yields a transparent fluid, owing to the formation 
of magnesium copaivate and solution of this soap in the essential 
oil. With an equal weight of the carbonate enough soap is pro- 
duced to take up the whole of the essential oil and form a mass 
capable of being rolled into pills. A much smaller quantity of cal- 
cined magnesia, as might be expected, effects the same result, but 
more time, often several days, is required before complete reaction 
is effected. The Massa Copaibce, U. S. P., is formed from 6 parts 
of magnesia and 94 of copaiba, and a little water. Quicklime has 
a similar effect. Perhaps carbonate reacts more quickly because of 
its fine state of division and admixture of hydrate, in which case 
calcium and magnesium hydrates may be expected to act better 
than the calcined preparations, and in much smaller quantity than 
magnesium carbonate. Copaiva, unlike, 3, Wood Oil, or Gurjun 
Balsam (Dipterocarpi Balsamum, P. I.), a similar oleo-resin from 
the Dipterocarpus turbinatus (D. Lcevis, P. I.) is almost entirely 
soluble in absolute alcohol and in petroleum spirit. Copaiva is 
often slightly fluorescent; Gurjun balsam is highly fluorescent. 
The stated analogy of Gurjun balsam to copaiva is borne out by its 
chemical composition ; for by distillation it yields about 40 per cent. 
of an essential oil identical in composition with oil of copaiva, the 
non-volatile portion being resinous. The adulteration of copaiva 
with fixed oil is best detected by heating 20 or 30 drops in a capsule 
until all essential oil has evaporated. (Turpentine is betrayed by 
its odor during this evaporation.) The residue, copaiva resin, is 
brittle if pure, and more or less sticky or soft if fixed oil is present. 
The limit of brittleness is stated, by Siebold, to be reached when 1 
per cent, of oil has been added to the copaiva, that amount prevent- 
ing the residue being reduced to a fine powder. " On adding 1 drop 
of copaiba to 19 drops of carbon disulphide, and shaking the mix- 
ture with 1 drop of a cold mixture of equal parts of sulphuric and 
nitric acids, it should not acquire a purplish-red or violet color 
(absence of Gurjun balsam)." — U. S. P. Resina Copaiba, U. S. P., 
is the residue left after distilling off the volatile oil from copaiba. 
4. Oleo-resin of cubebs ( Oleo-resina Cubebce, B. P.) is an ethereal 
extratct of cubebs decanted from waxy matter. (See Piperine and 
Oil of Cubebs.) 5. Elemi {Elemi, B. P.) is an exudation from a 
tree growing in the Philippine Islands. It consists of volatile oil 
(C 10 H 16 ) with 80 or more per cent, of two resins, the one (C 20 H 32 O 2 ) 
soluble in cold alcohol, the other, Amyrin, (C 5 H 8 ) 5 H 2 0, almost insol- 
uble, associated with Amyric acid (C 5 H 8 ) 7 4 (Buri). There is an 
a and a j3 amyrin, each having the formula C 30 H 49 OH (Vesterberg). 
It also contains small quantities of two crystalline bodies soluble in 
water, Bryoidin, (C 5 H 8 ) 4 3H 2 0, and Breidin (Fliickiger). The icacin 
of Stenhouse and Groves is either identical with amyrin or perhaps 
has the formula (C 6 H 8 ) 9 H 2 0. All these bodies are probably hydrous 
terpenes. 6. Wood-tar (Pix Liquida, U. S. P.) is mixture of sev- 
eral resinoid and oily bodies (amongst others creasote ; see Index) 
obtained by destructive distillation from the wood of Pinus sylvestris 



GUM-RESINS. 427 

and other pines. When heated, it yields a terebinthinate oil ( Oleum 
Picis Liquidce, U. S. P.) and a residue of pitch. (Earth Pitch, or 
Asphalte, appears to be a partially oxidized petroleum.) Oleum 
Cadinum, U. S. P., " Huile de Cade" or Juniper Tar Oil, is the 
product of the similar destructive distillation of the Juniperus Oxy- 
cedrus. 7. Turpentines. — These oleo-resins have been mentioned 
in connection with oil of turpentine, their volatile, and resin, their 
fixed constituent. 8. Common Frankincense Thus Americanum, 
B. P.) is the concrete turpentine of Pinus tozda. 9. Canada Balsam 
(Terebinthina Canadensis, B. P.) is largely gathered in the province 
of Quebec, and is the turpentine or oleo-resin of the balm of Gilead 
fir (Abies balsamea). 10. Sumbul-root, from Ferula Sumbid (Sum- 
bul, U. S. P.), contains 9 per cent, of resin, to which probably it 
owes its stimulating properties. The resin consists of two parts, 
one soluble in ether and the other in alcohol, together with vale- 
rianic, sumbulic, and sumbuolic acids. By dry distillation it yields 
a blue oil. 11. Oleo-resin of Lupulin (U. S. P.) is an ethereal 
extract of the yellow glandular powder [Lupulinum, B. P.) attached 
to the small nuts at the base of the scales which form the aggregate 
fruit of the Humulus Lupulus, or hop [Humulus, U. S. P.). It 
contains essential oil of hop (valerol, C 6 H 10 O), a terpene, C 10 H 16 , 
oxidized oil or resin, bitter extract containing the hop-bitter, lupu- 
linic acid (C 32 H 50 O 7 ), and tannic acid. It generally contains a good 
deal of earthy dust, but should not yield more than 15 per cent, of 
ash and not more than 30 or 40 per cent, of matter insoluble in 
ether. Oleo-resince Aspidii, Capsici, Cubebce, Lupulini, Piperis, 
and Zingiberis are official in' the United States Pharmacopoeia. 12. 
Pix Canadensis (Canada Pitch or Hemlock Pitch) is the concrete 
juice of Abies Canadensis. 

Gum-resins. — 1. Ammoniacum ■ (Ammoniacum, U. S. P.) is an 
exudation from the Dorema Ammoniacum. It contains nearly 20 
per cent, of gum, a little volatile oil, and about 70 of resin (C 40 H 50 O 9 
— Johnston). 2. Asafoetida (Asafcetida, U. S. P.) formerly spelt 
assafoetida, is a gum-resin obtained by incision from the living root 
of Ferida Narthex. It contains from 50 to 70 per cent, of a resin 
which is partly ferulaic acid (C 10 H 10 O 4 ), 25 to 30 per cent, of gum 
(about two-thirds arabin, one-third bassorin, p. 116), a little vanillin, 
and 3 to 5 per cent, of volatile oil, which (Semmler) contains two 
sulphur compounds, C 17 H 14 S and C n H 20 S 2 , two terpenes, C 10 H 16 , and 
a sesquiterpene, C 15 H 24 . 3. Fuphorbium, an old drug which is an 
emetic and purgative gum-resin, contains an amorphous active resin 
(C 20 H 32 O 4 ), crystalline euphorbon (C^H^O,,) and mucilage (Fluckiger). 

4. The ordinary or Siam Gamboge (Gambogia, U. S. P.) of European 
trade is obtained from the Garcinia Hanburii ; the gamboge of 
India (Cambogia Indica vel Mysoriensis, P. I.) from G. pictoria. 
When of best quality -it contains about 20 per cent, of a gum and 80 
to 75 per cent, of a yellow resin termed gambogic acid (C 20 H 24 O 4 ). 

5. Galbanum (Galbanum, B. P.) contains from 20 to 25 per cent, of 
gum, about 65 per cent, of resin (C 40 H 54 O 7 ), and 3 or 4 per cent, of 
volatile oil. Moistened with alcohol, and then with hydrochloric 
acid, galbanum yields a purple color, due, probably, to the produc- 



428 ORGANIC CHEMISTRY. 

tion and oxidation of resorcin. Galbanum heated for some time to 
212° F. with hydrochloric acid, the liquid separated and shaken 
with ether or chloroform, and the latter evaporated, yields somewhat 
loss than 1 per cent, of colorless acicular crystals of umbelliferone 
(CgHgOg). " Umbelliferone is soluble in water ; its solution exhibits, 
especially on addition of an alkali, a brilliant blue fluorescence 
which is destroyed by an acid. If a small fragment of galbanum is 
immersed in water, no fluorescence is observed, but it is immediately 
produced by a drop of ammonia. The same phenomenon takes place 
with asafoetida, and in a slight degree with ammoniacum ; it is prob- 
ably due to traces of umbelliferone pre-existing in those drugs. 
Umbelliferone is also produced from many other aromatic umbellif- 
erous plants, as Angelica, Levisticum, and Meum,, when their respect- 
ive resins are submitted to dry distillation ; also from the resin of 
Daphne mezereum. The fluorescence of umbelliferone may be 
beautifully shown by dipping some bibulous paper into water which 
has stood for an hour or two on lumps of galbanum, and drying it. 
A strip of this paper, placed in a test-tube of water with a drop of 
ammonia, will give a superb blue solution, instantly losing its color 
on the addition of a drop of hydrochloric acid " (Fliickiger and Han- 
bury). 6. Myrrh (Myrrha, U. S. P.), an exudation from the stem 
of Balsamodendron myrrha, contains about half its weight of soluble 
arabinoid gum, 10 per cent, of insoluble gum (probably bassorin), 
2£ of volatile oil isomeric with thymol and carvol (Kohler), and 
about 25 per cent, of resin (myrrhic acid). (For a note by It. H. 
Parker on the spurious gums imported with myrrh see the Pharma- 
ceutical Journal for July 17, 1880.) 7. Olibanum (P. I.). Thus 
masculum or Arabian Frankincense (from various species of Bos- 
wellia) is about one-third gum and nearly two-thirds resin (C 40 H 30 O 6 ), 
with a little hydrocarbon (C 10 H ]6 ) and oxidized hydrocarbon volatile 
oils. It has always been an important ingredient of incense — myrrh, 
storax, benzoin, and such fragrant combustible resinous substances 
being other constituents. 8. Scammony. (See Index.) 

Gum-resins need only to be finely powdered and rubbed in a 
mortar with water to yield a medicinal emulsion in which the fine 
particles of resin are held in suspension by the aqueous solution of 
gum. 

QUESTIONS AND EXERCISES. 

What are the general chemical characters of volatile oils ? — How do 
volatile oils usually differ chemically from fixed oils? — Describe the 
usual process by which volatile oils are obtained. — How does natural tur- 
pentine differ from turpentine of trade ? — With what object is commercial 
turpentine rectified? — What is the chemical nature of india-rubber and 
gutta percha? — How is india-rubber vulcanized and converted into ebonite 
or vulcanite? — Mention the difference in composition between the volatile 
oils of Anthemis nobilis and Matricaria Chamomilla. — Give the systematic 
name for oil of horseradish. — State the general composition of the oil of 
lemon, lime, bergamot, citron, and cedra. — Name the constituents of oil 
of cloves. — In what respect does otto of roses differ from other oils ? — 
What class of substances forms the chief part of oil of rue? — How is 
camphor oil related to camphor ? — In what respects do Borneo or Sumatra 



BENZENE HYDROCARBONS. 429 

camphor and camphor oil differ from the corresponding products of Japan 
and China ? — How may borneol be artificially prepared ? — How do resins 
occur in nature ? — Distinguish between resins and camphors. — Mention 
the points of difference of resins, oleo-resins, gum-resins, and balsams. — 
Name the sources of common resin or rosin. — Enumerate some official 
articles of which the active constituents are resins. — Give the distin- 
guishing characters of Burgundy pitch. — What is the average proportion 
of oil and of resin in the so-called balsam of copaiVa ?— Explain the effect 
of magnesium carbonate, magnesia, and lime on copaiva. — Why do 
ammoniacum, asafcetida, gamboge, galbanum, myrrh, and similar sub- 
stances give an emulsion by mere trituration with water ? 



THE BENZENE SERIES OF HYDROCARBONS. 

The Benzene or Aromatic Series, C n H2u— 6- — This series is of great 
general interest. It yields, like other families of hydrocarbons, 
alcohols, haloid derivatives, aldehydes, acids, etc., obtained, however, 
as a rule by special rather than general methods. Just as the con- 
secutive members of the paraffin series of hydrocarbons may be 
regarded as derived by the displacement of a hydrogen atom of the 
previous member by the methyl (CH 3 ) group, or of a hydrogen atom 
in methane by a paraffin radical, so the consecutive members of the 
benzene series may for convenience of study be viewed as obtained 
by the displacement of hydrogen atoms in benzene by paraffin radi- 
cals, as in the following examples : 

Benzene or Phenoene, C 6 H 6 . 

Toluene, Benzoene, or Methylphenoene, C 7 H 8 or C 6 H 5 - CH 3 . 

Xylene or Dimethylphenoene, C 8 H 10 or C 6 H 4 - (CH 3 ) 2 . 

Mesitylene or Trimethylphenoene, C 9 H 12 or C 6 H 3 .(CH 3 ) 3 . 

Cymene or Methylpropylphenoene, C 10 H U or C 6 H 4 , CH 3 'C 3 H 7 . 
It is, perhaps, desirable, as suggested by Odling, to designate the 
first member of this series by the name phenoene rather than benzene, 
as its hydrate is termed phenol,' and its derivatives phenyls; e.g. 
phenylamine. Toluene (first obtained from balsam of Tolu, hence 
the name) then becomes benzoene ; from it benzoic acid is derived. 

The members of the benzene series are unsaturated hydrocarbons. 
A molecule of benzene itself readily absorbs two, four, or six atoms 
of chlorine, these being added on to the benzene, forming what are 
termed additive compounds, as distinguished from the true substitu- 
tional compounds, in which the hydrogen atoms in benzene are 
actually substituted by chlorine, bromine, etc. The derivatives of 
benzene may more or less readily be reconverted into benzene, a 
fact supporting the close structural or constitutional relationship 
between the many benzenoid bodies. 

Bodies having an aromatic odor are somewhat characteristic of 
the benzene series, hence the latter was originally termed the aro- 
matic series of organic compounds. 

Benzene, or Benzol. 

Benzene or Phenoene, C 6 H 6 (commercially known as Benzol).* — 



* Care must be taken to distinguish between benzene, C6H6, and benzin, 
19* 



430 ORGANIC CHEMISTRY. 

Commercially it is obtained from the portion of coal-tar boiling 
below 100° C. It is partially purified by shaking successively with 
sulphuric acid, water, and caustic soda, and then redistilling, the 
product still containing large quantities of toluene and other impuri- 
ties. If pure benzol is required, the liquid must be subjected to a 
freezing mixture, when the benzol crystallizes out, leaving some 
impurities in solution ; the crystals are well drained. Bromine is 
then added to the liquid resulting from the melting of the crystals 
until a permanent coloration results. The liquid is again washed 
with caustic soda, and distilled. Benzene boils at 81° C. It may 
be artificially produced by heating benzoic acid with lime or by 
passing acetylene through red-hot tubes. It is a colorless, limpid, 
refractive liquid, having a specific gravity of 0.899 at 0° C. It is a 
powerful solvent of grease, and under the name of " Benzene Collas ' ? 
was introduced by M. Collas in 1848 for cleansing purposes. 

Benzene, when acted on by chlorine and bromine in the presence 
of a little iodine, forms all derivatives from monochloro- and mono- 
bromo-benzene (C 6 H 5 C1 and C 6 H 5 Br) to hexachloro- and hexabromo- 
benzene (C 6 C1 6 and C 6 Br 6 ). It also forms iodine and fluorine deriva- 
tives, nitro-derivatives, etc. 

Nitrobenzene (nitrobenzol, artificial oil of bitter almonds, or 
essence of mirbane), C 6 H 5 N0 2 , is obtained by mixing fuming 
nitric acid or a mixture of nitric and sulphuric acids with ben- 
zene, the vessel being kept cool by immersion in water. It is 
a yellow liquid, heavier than water, having a strong odor of 
oil of bitter almonds, though of very different nature. ( Vide 
" Oil of Bitter Almonds " in Index.) When acted on by nas- 
cent hydrogen it yields aniline. 

Aniline or Plienylamine or Amidobenzene, C 6 H 5 NH 2 * — Mix 
13 parts of iron filings, 7 or 8 of the ordinary acetic acid, and 
13 of nitrobenzene in a large flask (with an upright condenser) 
placed in a water-bath, and set the whole aside for some time. 
After the mixture has digested for several hours the superna- 
tant liquid is poured off from the deposit of iron filings and 
distilled in a current of steam. By this method the nitroben- 
zene yields, first, aniline, distilled over as a yellow oil, and 
afterward a red oil, which is a mixture of azobenzene (C 6 H 5 — 
N = N - C 6 H 5 ), hydrazobenzene (C 6 H 5 - NH - NH - C 6 H 5 ), 
and azoxybenzene (C 6 H 5 — N\T)7N — CeH 5 ). 

petroleum ether, benzolin, etc. (Petroleum Spirit, B.P.), which are mix- 
tures of paraffin hydrocarbons of lower boiling-points. Benzin (U. S. P.), 
C5H12 : CeHu, and other hydrocarbons of the paraffin series having the 
boiling-point of 122°-140° F., require six times the bulk of alcohol for 
solution, whereas benzene, C6H6, dissolves in less than its own bulk. 
Specific gravity of benzene, about 0.850; of benzin, about 0.700. 

* Aniline maybe obtained from indigo, hence its name, anil being 
Portuguese for indigo. 



BENZENE HYDROCARBONS. 431 

Aniline, C 6 H 5 NH 2 (mixed with toluidine, C 7 H 7 NH 2 ), when acted 
on by arsenic acid or chlorinated lime produces rosaniline, C 20 H 19 N 3 , 
whose salts and derivatives form most of the well-known aniline colors. 

Constitution of Amines. — Amines are usually viewed as deriva- 
tives of ammonia, one, two, or three atoms of hydrogen being re- 
placed by one, two, or three univalent organic radicals or equiv- 
alents of radicals of higher quantivalence. The products were 
formerly known as amidogen (NH 2 ) bases, imidogen (NH) bases, 
and nitrile (N) bases, but are now termed primary, secondary, and 
tertiary amines. The class includes certain alkaloids. 

Amides result when NH 2 displaces OH in acids. Acetic acid = 
CH 3 COOH ; hence acetamide = CH 3 CONH 2 . Aniline boiled with 
strong acetic acid yields phenyl-acetamide, or acetanilid (Acetani- 
lidum, U. S. P.) or " antifebrin," a febrifuge, C 6 H 5 NHC 2 H 3 (a 
rival of " antipyrine" C u H 12 N 2 0, phenyl dimethyl-pyrazolon, C 6 H 5 - 
(CH 3 ) 2 C 3 HN 2 (Phenazonum, B. P.), from phenylhydrazine or aniline 
and aceto-acetic ether). Monobrom-acetanilide, C 6 H 4 BrNHC 2 H 3 0, 
is a sedative and febrifuge. Phenacetin (Phenacetinum, B. P.), or 
para-acetphenetidin, C 6 H 4 , OC 2 H 5 "NH*C 2 H 3 0, is another febrifuge. 
Phenecoll, amido-acet-phenetidin, C 6 H 4 , OC 2 H 5 *NHCOCH 2 NII 2 , Para- 
phenetol-carbamide, or dulcin, is a body having a very powerful 
sweet taste, and proposed for use, like saccharin, in place of sugar. 

Acetanilid occurs in " white, shining, micaceous, crystalline 
laminae or a crystalline powder, odorless, having a faintly burning 
taste, permanent in the air. Soluble at 15° C. (59° F.), in 194 parts 
of water and in 5 parts of alcohol in 18 parts of boiling water and 
in 0.4 part of boiling alcohol ; also soluble in 18 parts of ether, and 
easily soluble in chloroform. Heated to 113° C. (235.4° F.), it melts. 
It is neutral to litmus-paper. On heating about 0.1 grm. with a few 
cc. of concentrated solution (1 in 4) of potassium or sodium hydrate 
the characteristic odor of aniline becomes noticeable. On now 
adding chloroform and again heating, the disagreeable odor of 
isonitril (which is poisonous) is evolved. On boiling 0.1 grm. for 
several miuutes with 2 cc. of hydrochloric acid, a clear solution re- 
sults, which, when mixed with 3 cc. of a 5 per cent, aqueous solution 
of carbolic acid, and afterward with 5 cc. of a filtered, saturated 
solution of chlorinated lime ( Calx chlorata), acquires a brownish-red 
color, becoming blue upon supersaturation with ammonia. A cold 
saturated aqueous solution, added to ferric chloride, should not 
affect the color of the latter (absence of aniline salts and various 
allied substances)." — XI. S. P. 

Toluene, Benzoene, Methyl-phenoene, or Methyl-benzene (commercially 
known as Toluol), C 6 H 5 CH 3 , forms the principal portion of coal-tar, 
boiling between 100° and 120° C. ; it may be synthetically made by 
acting on monochlorobenzene and iodomethane by sodium. 

C 6 H 5 C1 + CH 3 I + Na 2 == C 6 H 5 CH 3 + Nal + NaCl. 

It is also obtained by the dry distillation of Tolu balsam. It is 
an inflammable, refractive liquid, boiling at 111° C. It may be 
directly oxidized to benzoic acid. 

2C 6 H 5 CH 3 + 30 2 =2C 6 H 5 COOH -f 2H 2 0. 



432 



ORGANIC CHEMISTRY. 



Having both a phenyl (C 6 H 5 ) and a methyl (CH 3 ) group in its 
molecule, it forms two sets of isomeric derivatives — one (a) in which, 
by acting on toluene in the cold, the atoms of hydrogen are dis- 
placed in the phenyl group, and the other (6) by acting on boiling 
toluene, in which the atoms of hydrogen in the methyl group are 
displaced.* 

( Tolyl chloride, or methylmonochlorobenzene, C 6 H 4 CTCH 3 . 

a < Tolyl dichloride, or methyldichlorobenzene, C 6 H 3 C1 2 CH 3 . 

( Tolyl trichloride, or methyltrichlorobenzene, C 6 H 2 C1 3 CH 3 . 

JMonochloromethylbenzene, or benzylchloride, C 6 H 5 CH 2 C1. 
Dichloromethylbenzene, or benzyl dichloride, C 6 H 5 CHC1 2 . 
Trichloromethylbenzene, or benzyl trichloride, C 6 H 5 CC1 3 . 
Dichloromethylbenzene, when acted on by glacial acetic acid and 
zinc chloride and water, produces benzoic aldehyde, C 6 H 5 COH 
(Jacobson). By acting on trichloromethylbenzene by water in 
sealed tubes benzoic acid results. 

C 6 H 5 CC1 3 + 2H 2 = C 6 H 5 COOH + 3HC1. 
Cymene, C 10 H 14 . — Propylmethylbenzene, C 6 H 4 (CH 3 )(C 3 H 7 ), occurs 
in several volatile oils, and is readily obtained by the removal of 
hydrogen from the terpenes (C 10 H 16 ) of those oils. Many of the 
members of the benzene 'series have an aromatic odor, hence the 
synonym aromatic series. 



Constitution of the Benzene Series. 







The fact that benzene forms three additive derivatives with chlorine, 
C 6 H 6 C1 2 , C 6 H 6 C1 4 , and C 6 H 6 C1 6 , one molecule uniting with not more 
than six atoms of chlorine, and that it affords no isomeric monosubsti- 
tution derivatives (but only one toluene, C 6 H 5 CH 3 , one benzoic acid, 
C 6 H 5 COOH, and one only of all such derivatives, led Kekule to repre- 
sent benzene by the following figure (a), in which each atom of carbon 
is assumed to be " linked" to adjacent atoms of carbon by three- 
fourths of its affinity, the remaining fourth of its attraction being ex- 
erted toward the equivalent attraction of another atom, thus (Fig. a) : 



Fig. a. 

H 
C 



HC CH 

I II 

V 

.c 

H 

Benzene. 



Fig. d. 



~<7\ 




c 

HCl 

Hexachlorobenzene. 



* " Benzyl " is the name given to the derivatives of benzoene when 
substitution takes place in the methane nucleus, " tolyl " when in the 
phenoene nucleus. 



OTHER HYDROCARBONS. 433 

In a monosubstitution-derivative such as chlorobenzene, C 6 H 5 C1, no 
matter where the atom of chlorine be placed, it bears the same rela- 
tion to the atoms of hydrogen ; hence there can be only one variety 
of such a derivative. The experimental evidence of the truth of 
this inference is as follows : Displace H in benzene by another 
radical X, and obtain C 6 H 5 X. In the latter displace H by Y, and 
obtain C 6 H 4 XY. Now displace X by H, and obtain C 6 H 5 Y. Lastly 
displace Y by X, and obtain CgH 5 X. The first C 6 H 5 X and the last 
C 6 H 5 X are identical in properties, yet manifestly the latter X is in a 
different position to the first X : whence we conclude that actual 
position matters nothing if relative position is unchanged. Such 
hydrocarbons are symmetrical. Such mono-X compounds are un- 
symmetrical. Further displacements of II by X in C 6 H 5 X result in 
more than one variety of C 6 H 4 XX. In dichlorobenzene, C 6 H 4 C1 2 . 
the atoms of chlorine may (representing, for the moment, benzene 
by a hexagonal figure (6), and assuming that the carbon atoms are 
at the angles) be placed either at 1 and 2, 1 and 3, or 1 and 4, the 
chlorine atoms being either near to each other, separated by one 
carbon atom or by two carbon atoms. So with other di- derivatives. 
In trichlorobenzene, C 6 H 3 C1 3 , the atoms of chlorine may be placed at 
1, 2, and 3, 1,2, and 4, or 1, 3, and 5 ; 1, 2, and 4 being the same as 
1, 3, and 4 ; 1, 2, and 3 the same as 1, 6, and 5, etc. ; that is to say, 
the chlorine atoms must all three be near to each other, or two near 
to each other and one be separated, or all three be separated as far 
from each other as possible in the molecule. So with other tri- 
derivatives. Hence, theoretically, there can only be three isomeric 
di- and trichlorobenzenes ; which has been verified by experiment. 
(For other illustrations, and for nomenclature, see p. 445.) 

In the additive compounds a second quarter of the affinity of the 
carbon atoms for each other is freed, so to say, for exertion toward 
the added chlorine atoms (Fig. c). The mind may be aided in 
forming an idea of the constitution of molecules like benzene by 
other figures, such as the prism [d) or wheel-like hexagon (e) — 
devices all of which embody the idea of the interdependence of each 
atom of the molecule on every other atom, the idea conveyed by the 
linkages, not only of a series of links of an open chain, as pictured 
on previous pages, but of a chain without terminal links, a contin- 
uous or closed or endless chain — the open chain with its ends linked 
together, and even sometimes also having cross linkages. 

OTHER SERIES OF HYDROCARBONS. 

The Naphthalene Series, C n H 2n _i 2 . 

Naphthalene (C 10 H 8 ; synonyms, Naphtalin, Naphtalene) is the 
chief member of the series. It is in condensed benzene nuclei 
(Erlenmeyer and Graebe, 1866). It is a volatile white crystalline 
body, in shining laminae, having a strong characteristic odor, insolu- 
ble in water, very soluble in boiling alcohol, ether, chloroform, car- 
bon bisulphide, and the fixed and volatile oils. Naphtalin is now 



434 ORGANIC CHEMISTRY. 

official (Naphtalinum, TJ. S. P.), and is much used for increasing 
the luminosity of coal-gas. Sulphuric acid should not be discolored 
by it, and if heated on a water-bath for five minutes should not 
acquire more than a pale-reddish tint (absence of contamination 
derived from coal-tar). 

Naphthalene by oxidation yields phthalic acid, C 6 H 4 (COOH) 2 , the 
anhydride of which, C 6 H 4 (CO) 2 0, fused with phenol, forms phenol- 
phthalein (U. S. P.), an alkalimetric indicator. With other phenols 
various colored bodies are produced ; for example, with resorcinol 
fluorescing which, treated with bromine, gives eosin. Such bodies 
are termed phthaleins. Of the two naphthyl-alcohols, or naphthols, 
or monoxynaphthalenes, C 10 H 7 (OH), a and j3, the latter is the well- 
known powerful antiseptic. 

Beta-naphthol (Naphtol, U. S. P.) crystallizes in colorless volatile 
leaflets, very soluble in boiling water and alcohol, and in cold chloro- 
form, ether, and in solutions of caustic alkalies. Ferric chloride 
imparts a greenish color to the solution of ^-naphthols, dinaphthol, 
C 20 H 12 (OH) 2 , separating out. 

" Naphtol should dissolve in 50 parts of ammonia-water without 
leaving a residue (absence of naphtalin), and the solution should 
not have a deeper tint than pale yellow (absence of various other 
organic impurities). If 0.1 grm. be mixed, in a test-tube, with 1 
drop of syrup and 5 cc. of water, and about 3 cc. of concentrated sul- 
phuric acid be then poured into the tube held in a slanting position, 
so that the liquids may form separate layers, a yellowish-brown 
color will appear at the zone of contact, which becomes darker on 
standing (absence of, and distinction from, alpha-naphtol, which pro- 
duces at once a crimson color, turning deep blue in the upper part 
of the zone on standing)." — U. S. P. 

The Anthracene Series, C n H 2n -i8. 



- ; _ 14 — lu; _ _ _ . ^ - - ^ 7 

its importance being due to the fact that artificial madder, or alizarin, 
is formed from it by the following reactions : Anthracene is first 
oxidized to anthraquinone by the influence of nascent oxygen. By 
acting on anthraquinone with fuming sulphuric acid it is easily con- 
verted into a derivative, which yields potassium alizarate when 
fused with caustic potash. 

Chrysophanic Acid (CH 3 C 14 H 5 (OH) 2 2 ) and the aloins are related 
to anthraquinone, chrysophanic acid being a dihydroxy-derivative 
of methylanthraquinone, and the aloins (C 16 H 18 7 ) yielding on oxida- 
tion aloxanthin or tetrahydroxy-methylanthraquinone. 

Aloins. 

Aloins. — The aloes of pharmacy [Aloe Barbadensis, U. S. P., and 
Aloe Socotrina, U. S. P.) is an evaporated juice, doubtless much 
altered by the temperature to which it is subjected. 

Aloe Purijicata, XL S. P., is the evaporated alcholic extract of 
Socotrine aloes. It contains a yellow crystalline substance, Aloinum, 



OTHER HYDROCARBONS. 435 

(U. S. P.), slightly varying chemically, but not medicinally, as derived 
from the respective species of aloes. Aloin is slightly soluble in 
cold water or spirit, but readily soluble in the hot fluids. Dissolved 
in alkalies, it rapidly decomposes, absorbing oxygen, but it is only 
slowly altered in neutral or acidified solutions. 

Aloin may readily be obtained from either kind of aloes by warm- 
ing with three or four times its weight of amylic alcohol, pouring 
off the solution, allowing it to stand for a few hours to crystallize, 
and washing the deposited aloin Avith ether or carbon bisulphide to 
remove resinoid matters. It forms in " minute acicular crystals or 
a microcrystalline powder, varying in color from yellow to yellowish- 
brown, odorless or possessing a slight odor of aloes, of a character- 
istic bitter taste, and permanent in the air." — U. S. P. 

Tests. — Ferric chloride turns an aqueous solution of aloin greenish- 
black. Basic lead acetate slowly precipitates aloin. 

Barbaloin, U. S. P. — This substance, first obtained by T. and H. 
Smith, occurs in minute crystals in Barbadoes aloes. It yields, by. 
the action of bromine and chlorine, substitution-compounds. Nitric 
acid dropped upon it produces a red color which soon fades. Boiled 
for some time with strong nitric acid, barbaloin gives, together with 
oxalic and picric acids, a yellow substance, chrysammic acid, which 
furnishes beautiful red salts (Tilden). Anthracene (C U H 10 ) has been 
obtained by deoxidation of barbaloin. 

Nataloin. — This body was discovered by Fluckiger in Natal aloes. 
It crystallizes readily in rectangular plates, either from spirit or 
from water. No bromine or chlorine substitution-derivatives have 
yet been found, but an acetyl compound has been analyzed (Tilden). 
Nataloin moistened with nitric acid gives a red coloration which 
does not fade. When boiled with nitric acid it yields no chrysammic 
acid, but only oxalic and picric acids. 

Socaloin, IT. S. P., or Zanaloin. — Histed and Fluckiger have shown 
that Socotrine or Zanzibar aloes yields an aloin distinct from those 
just described. It forms tufted acicular prisms. Nitric acid 
scarcely alters the color of socaloin (difference from barbaloin). 
Neither socaloin nor barbaloin affords any color when vapor from a 
glass rod moistened with nitric acid is brought near to a drop of oil 
of vitriol containing a minute fragment of the aloin, while nataloin 
gives rise to a blue coloration. 

Analysis. — To aloin or powdered aloes on a white plate add 
strong nitric acid. No color = socaloin. Crimson color = nataloin 
or barbaloin. To another portion add strong sulphuric acid and 
vapor of nitric acid. A blue color = nataloin. No blue color = 
barbaloin. 

(For other methods of distinguishing the aloins and other allied 
bodies see a paper on Aloins by Cripps and Dymond, Pharmaceutical 
Journal, February 7, 1885.) 

E. von Sommaruga and Egger r (" Pharmacographia ") arrived 
at the conclusion that the aloins form an homologous series, and 
that they have the composition indicated in the following formulae : 
Socaloin, C 15 H 16 7 ; nataloin, C ]6 H lg 7 ; barbaloin, C 17 H 20 O r Tilden's 
subsequent experiments indicate, however, that barbaloin (C 16 H 18 7 ) 



436 ORGANIC CHEMISTRY. 

and socaloin (C 16 H 18 7 ) are isomeric in the anhydrous state, but that 
socaloin and its derivatives in the hydrous condition contain more 
water of crystallization than barbaloin. Nataloin (C 16 H 18 O v ) seems 
to be isomeric with the others, but is less soluble, and does not yield 
either chrysammic acid or chloro- or bromo-derivatives (C 16 H 15 C1 3 7 ; 
C 16 H 15 Br 3 7 ). The acetyl-derivatives appear to have the formula 
C 16 H 15 (C 2 H 3 0) 3 7 . According to Graenewold, the formula for the 
aloin from the aloes of Barbadoes and Curac.oa is C 16 H 16 7 , and that 
from Natal aloes C 24 H 26 O 10 . 



QUESTIONS AND EXERCISES. 

What is the formula of benzene ? — How is it artificially and commer- 
cially prepared ? — Draw out an equation explanatory of the production 
of aniline. — What is the relation between toluene and benzoic acid ? — 
Give the formulae of naphthalene and anthracene. — Explain by equations 
the production of alizarin or artificial madder. — Give tests for distin- 
guishing the aloins. 



The student is referred to the accompanying table for a general 
view of the relations of four series of hydrocarbons (the paraffin, 
benzene, naphthalene, and anthracene series) to each other. Three 
members of the paraffin series are shown, two of the benzene series, 
and one each of the naphthalene and anthracene series. Beneath 
each hydrocarbon are given its chief derivatives. A glance along the 
table shows the relations of the derivatives to each other. 



ALCOHOLS. 

Alcohols are those bodies in which one or more hydrogen atoms 
of the hydrocarbons are displaced by one or more hydroxy 1 (OH) 
groups, forming (a) monhydroxyl derivatives, (b) dihydroxyi de- 
rivatives, etc. ; they are, in fact, hydrates of unsaturated or radical 
hydrocarbons, just as caustic potash and slaked lime are potassium 
and calcium hydrates, thus : 

C 2 H 5 OH KHO, or KOH 

Ethyl hydrate. Potassium hydrate. 

C 2 H 4 (OH) 2 Ca(HO) 2 

Ethylene hydrate, or glycol. Calcium hydrate. 

C 3 H 5 (OH) 3 Bi(OH) 3 

Glyceric hydrate, or glycerin. Bismuth hydrate. 

a. Monhydroxyl Derivatives of Paraffins. 
The Ethylic Series of Alcohols, C n H 2n+ iOH. — The alcohols, or 
carbinols (Kolbe), are primary, secondary, or tertiary according as 
one, two, or three atoms of hydrogen in the first (or hydrogen) mem- 
ber of the series (methylic alcohol or carbinol itself, CH 3 OH) are 



To, 

Hi 



T„/„rr„, iM. 




SYN< 


I'Tic.U. TABLE SHOWING THE RELATIONS BET\ 


EEN THE PRINCIPAL MEMBERS OF THE PARAFFIN, BENZENE. 


NAPHTHALENE, AND 


VN'TIIRACK 


TE SEKIKS OP 11 


YDR.OCARBONS, AND BETWEEN 


Til KIR DERIVATI 


VKS. 






Hydrocarbon 


|CHi 


Methane. 


C 2 He or CHst'Hi 




1 Ethane ov Methyl- 
] methane 


C 3 H 8 or CMBWJH, { Pr m °£ n e e 0r Ethy '' 


CbHs 


1 Phenoene or 
i Benzene 


C 7 H 8 or CVH: 


CH 3 


1 Benzoene, Toluene or Me- 

, thylphenfietie 


CioHs Naphthalene 


C14H10 


Anthracene 


Ai.kvt. Salt, or 
Ethereal Salt, 

ETC. 


CHsCL 
CHnNOs 


1 Methyl chloride ov 

i Chlov sthane 


CJfcClorCHaC^ 




1 Ktliyl chloride or 
1 Chloroethane 


C 3 H,C1 or C.H6.C H 2 C1 { Pn W l coloride ov Chlor °- 
1 propane 


CsHbCI 


| Phenyl chloride or 
• 1 Chlorobenzene 


C7H7CI or J 


iHiCl.CH.i 
sH5.CH2.Cl 


, ,. , . , Tolyl chloride 
1 morotoinenes Benzyl chloride 


., t, ... f Naphthalene chloride 
UoHtI-i 1 Chloijonaphthaleni 


ChHoCI 


1 Anthracene chloride 
1 Chloroanthracene 


[ M S,nSe 01 ' 


C2H5NO2 or C'HaCHjHOj 


1 Ethyl nitrite or 
, Nitroethane 


C H7NO2 in- CsH-CH- NO. .1 Propyl nitrite or N/itro- 
! '* J ' ( propane 


MMTO. 


1 Phenyl nitrite or 


CjH r N02 0r^ 


iH1.NO2.CH3 


Vitrotoluenes Tolyl nitrite 
Benzyl nitrite 


Cii.IItN'Oj Nitionaphtliilleoi- 




Amine 

MONHYDBIC AI.COIIOI 


I 11, Nil, 




C2H5NH2 or CHsCH>NH« 


Ethylamine 

( Ethyl alcohol or Me- 
i thylcarbiuol 


C3H7NH2 or C2H5CH2.NH2 Propylamine (VII-.XH: 


( Pheuylamine or 
1 Aniline 


OjHTNHsorj 


;&£& 


B^yTmL 


CioHtXH-j Naph 


halamine 


('11,1)11 ... 
HCHsOH 


Mi-tliyl iil.-.jhul or 
( lavbinol 


CjH 6 OH or CHsCHsOH 


| Primary Propyl Alcohol 

,,„„„ ,. 1 C2H5.CH2.OH „r i'.ll.vl .-arlMii.,1 , . ,, 
( -N;( 'I 1 -I! , .,, , .|, , ill „ 1 1» 1 M 11 '- 11 ' " 
( (Crl3)2Crl.OH S.o, Inlaw I'liipyl Alr.ill.il 


J Phenyl alcohol or 
) Phenol 


CtHt.OH or [ 


iHi.oH.ca 

iHjCHsOH 


Benzyl alcohol or Phenyl i-arbinid 


CiiHtOII j N! ^.'. 1 i ' 




( nll-.dll 


1 Anthracene alcohol 
, Antlirnl 


C«H.(OH)j or CH2OH.CH1OH 


1 Ethylene glycol or 
I Glycol 


CsHu' OH I2 or C2H4OH.CH2OH Propylene glycol 


1 Pyincatechin 

Eesorcin 
1 Hydroquinone 


CjH 6 (OHl-.i,i 


(',;Hi.011.('ll : (Hi 


Si.li.vl iih-i.hirl. Saligenid nc lly- 


CioHnlOH 2 | N ^ ph 


haqitinol or Di- ( , „ 0fi ) Anthi-aquinol or Di- 

■«)\yn;ij.|iili;il.!i,' - , hydrosyaiithracene 


TBIHYDBIC ALCOHOL 






CsHslOHl:, 01- C'2Hs(OH) 2 CH20H Glycerol or Glycerin CVH, oil 


Pyi-ngallol or I'yro- 
, gallic acid 




CoH, 0H) 3 j Tl ^te ne 






A ''"' ; " V '" : 

KKT " NK 

NlTRII.lt 

Monobasic Vcid 

1 M I,\,l, ir 


II .CO. II 


| Formic aldehyde 


C,H,()..i CHs.CO 1 


Acetic aldehyde 


CsHuO or C 2 H 5 .t'O.H Propionic aldehyde 1 


CtHbO or CoH 


i.f'O.H 


Benzoic aldehyde 










C3H0O or CH3.CO.CH3 | A ketmi, 01 Dlmethyl 








HCHaCN 


I Acetonitrile or Me- 
thyl cyanide 


C2H5CN or CHjC'HjCN 


! ''"eiMvi'i'vIuu-U- 


CaH,CN or C 2 H 5 I IH2CN j B, e y S! 1 (p , riZry? ,, '' ' j ' ' ' ' ■' ' 


1 Bcnziiiiitrile or 
i Phenyl cyanide 


(MItCX orC 




Benzyleyiuii,,,. 


C10H1CN ' t^'ljj 1 


l;;:; 1 ^:'.; ,, 


II.CO.OII. 


Formic acid 


t',.II,o, orCHn.l O.I 


11 ^tUfo"'- °'-i )U " 


r mn „,. c w- rr> mtt f P™P iol . 1R ' add m Ethyl- 
C 3 Hs02 or C2H5.CO.OH j f orm ic acid 




CiHaOjorCnI 


fcCO.OH 


Benzoic acid or Phenyl-formic 

acid 






Monobasic Acid 

(Dihydric 

Monobasic \t id 

[Yihydvii 

Dibasic Acid 


OH.CO.OH. 


i Hydvoxyl'mmii- acid 


ftH.03 or CH»OH.( 


O.OH 


1 Glycoltie acid in- lly- 


1 '..H,i O.H,|OH).CO.OH ( L propionic acid Hydr ° X! '" 


CtHsOu (.1- ( ■« 


liOH.CO.OH 


Salicylic m-icl or Hydroxybenzoic 










aOJ.orCOOH.« 


Oxalic 


c.H.iO, ov C-jH-i(OH)2.CO.OH j ^JSonU; u!-id' V '' r " Xy " 
1 11 (CO.OH)j Malonicacidf 




CtHoO, or IV 


1 OH)j.( o.oil 


Dihydroxyhenzoicaeid 


~~ 






Ethkii 












1 ,11, 11 Propyl ether 


(CsHahO 


Phenyl ether 
is unusual. (See j.n>,'e 'il- ) 


I I'liis .-lit.. 




ct oxidation at Propylene glycol, Note.— This Table is a slielu exk-n 1 ' 


1,1 piled by I) 


. 



METHYLIC ALCOHOL. 437 

displaced by one, two, or three atoms of any radical having the gen- 
eral formula C»H 2n+ i. Thus : 

C n H 2n+1 ,X n H 2n+2 .X n H 2n+1 

I I SI II 

H— C— OH H— C— OH K— C— OH W— C— OH 

I I cf | d 5 I 

H H H C n H 2n+1 

Carbinol. Typical primary Typical secondary Typical tertiary 

carbinol. carbinol. carbinol. 

The primary oxidize their CH 2 OH group to aldehydes (bodies con- 
taining the aldehydic group, COH) and acids (bodies having the 
group COOH or carboxyl) ; the secondary oxidize their CHOH group 
to form a ketone (a body having carbonyl, CO // , as a group, as 
acetone CH 3 — CO — CH 3 ), and by further oxidation break up, form- 
ing bodies with less carbon units than the original alcohol ; while 
the tertiary yield a ketone and an acid. The primary alcohols alone 
are of practical interest to medical and pharmaceutical students. 
The tertiary alcohols are said to be depressants instead of stimu- 
lants. (For examples of primary, secondary, and tertiary alcohols 
see p. 449.) 

General Method of Preparing Primary Alcohols. — By acting on 
the monochloro-derivatives of a paraffin by potassium or silver ace- 
tate an ethereal salt (acetate) is produced, which when saponified 
with caustic potash yields the alcohol. For instance — 

C 2 H 5 C1 + AgC 2 H 3 2 = C 2 H 5 C 2 H 3 2 + AgCl 

Ethylic Silver Ethylic Silver 

chloride. acetate. acetate. chloride. 

C 2 H 5 C 2 H 3 2 -f KHO = C 2 H 5 OH + KC 2 H 3 2 

Ethylic Potassium Ethylic Potassium 

acetate. hydrate. alcohol. acetate. 

If the chloro-derivatives were directly acted upon by the potas- 
sium hydrate, hydrocarbons of the olefine or acetylene series would 
result. 

The chief primary alcohols are, however, otherwise obtained. 

Note on Nomenclature — The student will perceive that such names 
as those in the following set are used indifferently : ethylic acetate, 
ethyl acetate, acetate of ethyl, acetic ether. 

Methylic Alcohol. 

Methyl (fiedv, methu, wine, and vkn, ule, wood) Alcohol or Carbinol, 
CH 3 OH or HCH 2 OH (Pyroxylic Spirit or Wood Naphtha), is a prod- 
uct of the destructive distillation of wood, and is now obtained in 
large quantities as a by-product in the manufacture of beet-sugar 
in France. By oxidation it yields formic acid. (See p. 339.) 

Methylated Spirit. — Spirit of wine, containing 10 per cent, of 
wood spirit, constitutes ordinary methylated spirit, a spirit issued 
duty free for the use of manufacturers, the methylic alcohol, etc. 
not interfering with technical applications. From its nauseous 
taste and odor, however (not due to methyl alcohol, but to tarry 



438 ORGANIC CHEMISTRY. 

bodies), it cannot take the place of gin, brandy, or other spirit; 
hence, while industry is benefited, intemperance is discouraged and 
the revenue not injured. 

Detection of Methylic Alcohol in Presence of Etliylic Alco- 
hol—Three or four methods have been proposed for the detec- 
tion of methylated spirit in various liquids ; that most used 
by pharmacists is by J. T. Miller. For the application of the 
test to tinctures and similar spirituous mixtures some of the 
spirit is first separated by distilling off a drachm or so from 
about half an ounce of the liquid placed in a small flask or 
test-tube having a long bent tube attached. Into a similar 
apparatus put 30 grains of powdered red potassium chromate, 
i an ounce of water, 25 minims of strong sulphuric acid, and 
30 or 40 minims of the spirit to be tested. Set the mixture 
aside for a quarter of an hour, and then distil nearly half a 
fluidounce. Place the distillate in a small dish, add a very 
slight excess of sodium carbonate, boil down to about a quarter 
of an ounce, add enough acetic acid to impart a distinct but 
feeble acid reaction ; pour the liquid into a test-tube, add a grain 
of silver nitrate dissolved in about 30 drops of water, and heat 
gently for a couple of minutes. If the liquid then merely 
darkens a little, but continues quite translucent, the spirit is 
free from methylic alcohol ; but if a copious precipitate of 
dark-brown or black metallic silver separates, and the tube, 
after being rinsed out and filled with clean water, has a distinct 
film of silver, which appears brown by transmitted light (best 
seen by holding it against white paper), the spirit is methyl- 
ated. The experiments are best performed by daylight. 

Explanation. — This test depends for its action on the reducing 
powers of formic acid. In the above operation the ethylic alcohol 
becomes oxidized to acetic acid (the natural acid of the ethyl series), 
which does not reduce silver salts, a minute quantity only of formic 
acid being produced, while the methylic alcohol yields formic acid 
(the natural acid of the methyl series) in a comparatively large 
quantity. Aldehyde, which is also a reducing agent, is simultane- 
ously produced, but removed in the subsequent ebullition with car- 
bonate of sodium. 

Methylated Sweet Spirit of Nitre— The preparation of spirit 
of nitrous ether from methylated spirit is illegal in Great Brit- 
ain, and, probably, is very rarely practised. For the detection 
of methylic alcohol in this liquid Mr. Miller suggests the fol- 
lowing modification of the foregoing process : 

Shake about an ounce of the sample with 20 or 30 grains of 
anhydrous potassium carbonate, and, if needful, add fresh por- 
tions of the salt until it ceases to be dissolved, then pour off 



ETHYLIC ALCOHOL. 439 

the supernatant spirit. This serves to neutralize acid and to 
remove water, of which an abnormal quantity may be present. 
Introduce ^ a fluidounce of the spirit into a small flask ; add 
150 grains of anhydrous calcium chloride in powder, and stir 
well together ; then, having connected the flask with a con- 
denser, place it in a bath of boiling water, and distil 1| fluid- 
drachms, or continue the distillation until scarcely anything 
more comes over. The operation is rather slow, but needs 
little attention, and should be done thoroughly. The distillate 
contains nearly the whole of the nitrous ether and other inter- 
fering substances, while in the retort there remains a non-vola- 
tile compound of calcium chloride and methylic alcohol, if the 
latter be present. Now add to the contents of the flask a 
fluidrachm of water, which decomposes the compound just 
referred to, and draw over the half-drachm of spirit required 
for testing. Then proceed as described in the foregoing para- 
graphs. 

Ethylic Alcohol. 

Ethyl Alcohol, or Methyl Carbinol, commonly called simply 
Alcohol (C 2 H 5 OH or CH 3 CH 2 OH). — It is a colorless liquid, having 
a boiling-point of 173.6° F. and sp. gr. 0.7935. Ethyl alcohol may 
be obtained by passing ethylene into strong sulphuric acid. The 
product, ethylhydrogen sulphate, when distilled with water, yields 
alcohol : 

C 2 H 4 + H 2 S0 4 = C 2 H 5 HS0 4 
C 2 H 5 HS0 4 + H 2 = C 2 H.HO + H 2 S0 4 

On the large scale alcohol is produced by fermentation. All fer- 
mented bread retains a little alcohol, sometimes as much as 1 in 400. 

Formation of Alcohol. — Ferment two or three grains of sugar 
by dissolving it in a test-tube full of water, adding a little yeast 
( Cerevisise, Fermentum, B. P.) or a piece of the so-called Ger- 
man or dried yeast, and setting the whole aside for several 
hours in a warm place at a temperature of 75° to 85° F. ; car- 
bonic acid gas is evolved, and, if the tube be inverted in a 
small dish containing water, may be collected in the upper part 
of the tube and subsequently tested : the solution contains 
alcohol. If the experiment be made on large quantities (4 
ounces of sugar, 1 of yeast, and 1 pint of water), the fermented 
liquid should be distilled, one-half being collected, shaken with 
a little lime, soda, or potash to neutralize any acetic acid and 
decompose ethereal salts, and again distilled till one-half has 
passed over ; the product is dilute spirit of wine. It may be 
still further concentrated or rectified by repeating this process 
of fractional distillation, the separate fractions being redistilled, 



440 ORGANIC CHEMISTRY. 

then fractions having fairly near boiling-points being mixed 
and again distilled, and so on until the ethylic alcohol, the other 
alcohols (chiefly amylic alcohol), and the water, having had 
the cohesive tendencies of their molecules thus overcome, are 
separated from each other. The heads of stills can be so 
adapted, especially on the large scale, as to condense and deliver 
at once the substances having different boiling-points. 

Fermentation. — The act of fermentation is commonly the result 
of, or rather accompaniment of, some vital action. Alcoholic fer- 
mentation would appear to be always attended by, or to attend 
development of, life and free multiplication of cellular structure. 
It follows the development of the fungus already referred to as con- 
stituting the chief active part of yeast, the Saccharomyces cerevisice. 
In the presence of this fungus, with small quantities of phosphates 
and albumenoid matter, glucose is converted into alcohol and car- 
bonic acid gas, together with small portions of glycerin, succinic 
acid, and other substances. Yeast also contains a soluble ferment, 
invertase, analogous to diastase, which is capable of converting 
sucrose into glucose. Therefore if yeast be used, sucrose, or cane- 
sugar, may be converted into carbonic acid gas and alcohol, the sol- 
uble ferment first converting the sucrose, not itself fermentable by 
the saccharomyces, into glucose. 

C 6 H 12 6 = 2C 2 H 5 HO + 2C0 2 

Grape-sugar. Alcohol. Carbonic acid gas. 

Not more than 20 per cent, by weight of alcohol can be obtained 
in a fermenting fluid, for more than this proportion prevents fer- 
mentation. 

Other kinds of fermentation, arising from the action of special 
ferments which have not received in all cases distinctive names, are 
the following : Viscous or Mannitic fermentation, which occurs 
when beer or saccharine juices, such as that of the beet-root, be- 
come " ropy." Gum, mannite, and carbonic acid gas are produced. 
(For Lactic and Butyric fermentations see " Lactic Acid.") Putre- 
factive fermentation occurs when a liquid containing albumenoid 
matter is exposed to the air. Infusoria appear in the liquid, using 
up the dissolved oxygen, and the ferments of the genus vibrio are 
developed. These are protected from oxygen, which is fatal to 
them, by a thin surface layer crowded with bacteria — small rod-like 
organisms having powers of locomotion. The vibrionic action, or 
putrefaction, proceeds with evolution of sulphuretted hydrogen, 
together with other gases having unpleasant odors and of complex 
chemical constitution. (For Acetic fermentation see " Acetic Acid;" 
for Ammoniacal fermentation see " Urine.") 

Fermentation by Certain Soluble Albumenoids. — (For the conversion 
of starch into sugar by diastase see " Starch ;" of amygdalin into 
benzoic aldehyde, hydrocyanic acid, and glucose by emulsin see 
"Amygdalin-," of salicin into saligenin and glucose see " Salicin ;" 
of potassium myronate into allyl sulphocyanate, etc. by myrosin, 
see " Mustard ;" of cane-sugar into grape-sugar by the soluble fer- 



FERMENTATION. 441 

ment in yeast see the foregoing paragraphs.) Many soluble ferments 
or hydrolysis occur in the germinating seeds and other parts of 
plants, and play an important part in nutrition. 

The nomenclature of ferments and fermentation is slowly emerging 
from unavoidable confusion caused by growth of knowledge on the 
subject. The word fermentation originally described the action that 
goes on in the preparation of alcoholic fluids or of dough, for it is 
derived from the Latin ferves, I boil or seethe, in allusion to the 
production of gas. But discoveries of ferments so multiplied as to 
force classification, resulting in the names organized ferments (yeast, 
for example) and unorganized ferments (diastase, for example), also 
termed insoluble ferments and soluble ferments. Moreover, the word 
fermentation itself became scarcely applicable to many of these 
actions, which, otherwise strictly analogous, afforded no gas, no 
boiling or seething. Hence the word zymosis (from £17/77, zume, 
leaven) for the action of organized ferments (or zymes ?), while the 
soluble or unorganized ferments are termed enzymes, and their 
action one of enzymosis. All enzymes promote hydrolysis {vide 
Index), hence are hydrolysis. 

Alcoholic Fermentation. — The chief reaction results, as already 
stated, in the formation of alcohol and carbonic acid gas, though 

3 per cent, of glycerin, 0.5 of succinic acid, and traces of several 
other substances are simultaneously produced. ( Vide " Fousel Oil," 
in Index.) By this reaction is formed the spirit of the various 
kinds of wine, beer, and liqueurs, such as Orange Wine ( Vinum 
Aurantii, B. P.), made " by the fermentation of a saccharine solu- 
tion to which the fresh peel of the bitter orange has been added ;" 
Sherry Wine (Vinum Xericum, B. P.), the fermented juice of the 
grape; Whiskey (Spiritus Frumenti, U. S. P.), containing from 44 
to 50 per cent, of pure alcohol 5 Bay Rum, or Spirit of Myrcia 
{Spiritus Myrcia?, U. S. P.), by distilling rum with leaves of Myrcia 
acris, etc., or by dissolving the oils in alcohol ; and others. 

Alcoholic drinks vary much in strength. Cider or apple wine, 
perry or pear wine, and good beer (ale and porter or stout) contain 

4 to 6 per cent, of real alcohol ; good light wines, both " red" and 
"white," and natural sherry also, 10 to 12 per cent. ; strong sherry 
and port, which are commonly "fortified" — that is, contain added 
spirit — 16 to 18 per cent. ; while " spirits " (gin, rum, brandy, 
whiskey, etc.) and "liqueurs" (ratafia, almond-flavored ; maraschino, 
cherry-flavored ; cura^oa, orange-flavored ; chartreuse, a composite- 
flavored liqueur, etc.), are "under proof" or "over proof," terms 
explained in a following paragraph. For British excise purposes 
"beer" is any such liquid or substitute which contains more than 
2 per cent, of proof spirit. The well-known effects of these spirit- 
uous fluids on the animal system would appear to be due primarily 
to alcohol, and secondarily to ethereal derivatives of alcohols. Some 
owe a part of their effect to non-volatile substances, for beer from 
which all alcohol, etc. has been removed by ebullition is said to 
have considerable effect on the human economy. 

The official (U. S. P.) wines are all made with "white wine" 
( Vinum Album, U. S. P.), a kind of natural sherry, containing not 



442 ORGANIC CHEMISTRY. 

less than 10 or more than 14 per cent, of absolute alcohol. Vimim 
Rubrum, U. S. P., is of similar strength — a kind of natural port 
wine. 

Varieties of Alcohol. — The weak spirit, concentrated by distilla- 
tion till it contains 84 per cent, by weight of pure alcohol, is an 
ordinary article of trade ; its specific gravity at 60° F. is 0.8382. 
This is common Spirit of Wine, the Spiritus Rectificatus of the 
British Pharmacopoeia. The official Proof Spirit* {Spiritus 
Temtior, B. P.) contains 49£ per cent, by weight, 57 by volume, of 
alcohol, and is made by diluting 100 volumes of "rectified spirit" 
with water until the well-stirred product measures 156 volumes. 
Sixty volumes of water will be required for this purpose, the liquids 
occupying less bulk after than before admixture. In the language 
of the Excise authorities, the rectified spirit of the Pharmacopoeia 
would be described as " 56 degrees over proof" (56 O. P.) ; that is, 
100 volumes contain as much alcohol as is present in 156 volumes 
of proof spirit. Obviously, proof spirit may be made by diluting 
with water rectified spirit of any other strength than that mentioned 
above. Thus 100 fluidounces of a spirit of " 70 over proof " may 
be diluted to 170, or the same quantity of a spirit of " 50 over proof" 
may be diluted to 150, and so on. The specific gravity of proof 
spirit at 60° F. is 0.920. Spirit 10 per cent. " under proof" con- 
tains as much alcohol as would be present in spirit formed of 90 
volumes of proof spirit mixed with sufficient water to form 100 
volumes. According to British law, gin is not "adulterated" 
with water if it is not weaker than 35 degrees under proof; nor 
brandy, whisky, or rum if they are not weaker than 25 degrees 
under proof. 

Alcohol, U. S. P., contains 99 per cent, by weight ;' Alcohol 
Dilutum, U. S. P., 41 per cent, by weight (48.6 by volume), of real 
alcohol, the remainder being water. The former has a sp. gr. not 
higher than 0.797, the latter about 0.937 at 15.6 C, or 0.789 and 
0.936 respectively at 25° C. The stronger boils at 78° C. 

Heal Alcohol (C 2 H 5 HO) may be prepared from spirit of wine by 
removing the water which the latter contains. This is accomplished, 
partially, by anhydrous potassium carbonate, and finally and entirely 
by recently fused calcium chloride. In operating on, say, 1 pint, 
2 ounces of dried potassium carbonate is placed in a bottle that can 
be well closed, and frequently shaken during two days with the 
spirit. Meanwhile put rather more than a pound of calcium chlo- 
ride into a covered crucible, and subject it to a red heat for half an 
hour ; then pour the fused salt on to a clean stone slab, cover it 
quickly with an inverted porcelain dish, and when it has congealed 
break it up into small fragments and enclose it in a dry stoppered 
bottle. Put 1 pound of this fused calcium chloride into a flask, 

* Proof spirit is so termed from the fact that in olden times a proof of 
its strength was supposed to be afforded by moistening a small quantity 
of gunpowder and setting light to the spirit; if it fired the powder, it 
was said to be " over-proof;" if not, "under proof." The weakest spirit 
that would stand this test was what we should now describe as of sp. gr. 
0.920. 



ALCOHOLS. 443 



pour over it the spirit decanted from the potassium carbonate, and, 
closing the mouth of the flask with a cork, shake them together, and 
allow them to stand for twenty-four hours with repeated agitation. 
Then, attaching a dry condenser closely connected with a receiver 
from which free access of air is excluded, and applying the flame 
of a lamp to the flask, distil about 2 fluidounces, which should be 
returned to the flask, after which the distillation is to be continued 
until 15 fluidounces have been recovered. The foregoing details 
are those of the British Pharmacopoeia. The official Ethyl Alcohol, 
U. S. P., should not contain more than 1 per cent, by weight of 
water, and should have a specific gravity of 0.797 to 0.789. The 
product should be colorless, and of a characteristic but agreeable 
odor. It is entirely volatilized by heat, is not rendered turbid when 
mixed with water, does not cause anhydrous copper sulphate to 
assume a blue color even after the two have been well shaken 
together, and should leave no smell on a piece of blotting-paper 
when allowed to evaporate spontaneously on it. What little water 
remains may, if necessary, be removed by the cautious addition of 
a little metallic sodium. If 5 per cent, of sodium be used, solution 
of sodium ethylate or caustic alcohol results (Liquor Sodii Ethylatis, 

B. P.) by replacement of the hydroxyl hydrogen by sodium : 
Na 2 -f 2C 2 H 5 OH = 2C 2 H 5 ONa+ H 2 . The solution contains 19 per 
cent, of sodium ethylate. 

There is another strength of alcohol which is official, containing 
92.5 per cent, by weight of pure ethyl alcohol and about 7.5 per 
cent, of water. This is known as Alcohol Deodoratum, U. S. P., or 
Deodorized Alcohol. It has a sp. gr. of about 0.816 to 0.808. 

Spirit of French Wine (Spiritus Vini Gallici, U. S. P.), or 
Brandy, is a colored and flavored variety of alcohol distilled from 
French wine. Its color is that of light sherry, and is derived from 
the cask in which it has been kept, but it is commonly deepened by 
the addition of burnt sugar. Its taste is due to the volatile flavoring 
constituent of the wine, often increased by the addition of artificial 
essences. 

" A pale, amber-colored liquid, having a distinctive odor and taste, 
and a slightly acid reaction ; specific gravity should not be more 
than 0.941, nor less than 0.925, corresponding, approximately, to 
an alcoholic strength of 39 to 47 per cent, by weight or 46 to 55 
per cent, by volume. If 100 cc. of brandy be very slowly evaporated 
in a tared capsule on a water-bath, the last portions volatilized 
should have an agreeable odor, free from harshness (absence of fusel 
oil from grain or potato spirit), and the residue, when dried at 100° 

C. (212° F.), should not weigh more than 1.5 grm. This residue 
should have no sweet or distinctly spicy taste (absence of added 
sugar, glycerin, or aromatic substances). It should almost com- 
pletely dissolve in 10 cc. of cold water, forming a solution which is 
colored not deeper than light green by a few drops of dilute ferric 
chloride, made by mixing the latter with 10 volumes of water 
(absence of more than traces of oak tannin from casks). To render 
100 cc. of brandy distinctly alkaline to litmus should require not 
more than 1 cc. of potassium hydrate (limit of free acid)." — U. S. P. 



444 ORGANIC CHEMISTRY. 

The foregoing words are also used in describing Whiskey (Spiritus 
Frumenti) in the United States Pharmacopoeia, except that the sp. 
gr. is to be "not above 0.930 nor below 0.917, corresponding 
approximately with an alcoholic strength of 44 to 50 per cent, by 
weight or 50 to 58 per cent, by volume," and that the acidity is 
not to be greater in 100 cc. than 1.2 cc. of soda solution will neu- 
tralize. 

Tests. — There are no specific tests for alcohol when mixed with 
complex matters. It is, however, easily isolated and concentrated 
by fractional distillation, and is then recognizable by conjoint phys- 
ical and chemical characters. Thus its odor and taste are charac- 
teristic ; it is lighter than water, volatile, colorless, and when toler- 
ably strong inflammable, burning with an almost non-luminous 
flame ; it readily yields aldehyde (see below) and acetic ether {vide 
Index), each of which has a characteristic odor, and in presence of 
hot acid alcohol reduces red potassium chromate to a green chromium 
salt. 

According to Lieben, 1 of alcohol in 2000 of water can be detected 
by adding to some of the warmed liquid a little iodine, a few drops 
of solution of soda, again warming gently, and setting aside for a 
time ; a yellowish crystalline deposit of iodoform (CHI 3 ) is obtained. 
Under the microscope the latter presents the appearance of hexagonal 
plates or six-rayed and other varieties of stellate crystals. 

C 2 H 6 + 4I 2 + 6NaHO = CHI 3 + NaCH0 2 + 5NaI + 5H 2 0. 

Other alcohols, aldehydes, gum, turpentine, sugar, and several other 
substances give a similar reaction. 

Tests of Purity. — Oil or resin is precipitated on diluting spirit of 
wine with distilled water, giving an opalescent appearance to the 
mixture. The sp. gr. of rectified spirit is 0.838. Fousel oil, alde- 
hyde, and such impurities are detected by silver nitrate. (Vide 
Index, " Alcohol, Test for Purity of.") Water in absolute alcohol 
may be detected by adding to a small quantity a little highly-dried 
copper sulphate, which becomes blue (CuS0 4 ,5H 2 0) if water be pres- 
ent, but retains its yellowish-white anhydrous character (CuS0 4 ) if 
water be absent. 

Note. — Most ethyl derivatives are formed from alcohol, such as 
ethyl nitrite in spirit of nitrous ether, iodo-ethane, etc. These have 
been treated under " Ethane." Aldehyde and acetic acid are 
obtained from alcohol by oxidation. 



Alcohols and Ethers.— As already stated, just as such elementary 
radicals as potassium (K) form hydrates (as KOH) and oxides (as 
K 2 0), so do such compound radicals as ethyl (C 2 H 5 ) form hydrates, 
as common alcohol, C 2 H 5 OH, and other alcohols, p. 436, and oxides 
as common ether, (C 2 H 5 ) 2 0, and other ethers, p. 447. 

But Sulphur Alcohols, or Thio-alcohols, CH 3 SH, C 2 H 5 SH, etc., 
^ous to sulphydrates, KHS, etc., are known. They were 



ALCOHOLS. 445 

originally termed mercaptans (mercurius captans), from the readi- 
ness with which they took mercury captive, (C 2 H 5 S) 2 Hg. Sulphur 
Ethers, or Thio-ethers, also are known, (CH 3 ) 2 S, (C 2 H 5 ) 2 S, etc. 
The vapors of such sulphur compounds have an extremely unpleas- 
ant smell. 

Sulphonic Acids are products of the oxidation of the sulphur 
alcohols just mentioned. For example : 

2C 2 H 5 SH + 30 2 = 2C 2 H 5 -S0 2 'OH 

Ethyl-niercaptan. Oxygen. Ethyl-sulphonic acid. 

They also may be formed by acting on hydrocarbons with sulphuric 
acid. Examples : 

S °2<OH + C 6 H 6 = S ° 2 <OH 5 + H 3° 

Sulphuric acid. Benzene. Benzene-sulphonic acid. Water. 

SO *<OH + ^CHs = S0 2 <^ 4 CH 3 + Rfi 

Sulphuric acid. Toluene. Toluene-sulphonic acid. Water. 

Sulphonic acids are isomeric with acid sulphites, the character- 
istic sulphonic group or radical being S0 3 H, but the acid sulphites 
of the organic radicals are extremely unstable, the corresponding 
sulphonic acids very stable. Orthophenolsidphonic acid, C 6 H 4 - 
OH*S0 2 OH, sozolic acid, or aseptol, is a non-poisonous, non-irri- 
tating antiseptic. The di-iodoparaphenolsulphonic acid, or sozoiodol, 
CgH^OH'SO^OH, has similar properties, and is used instead of 
iodoform. 

Saccharin (Glusidum, B. P.; synonym, Glucusimide), which is 
a harmless, non-alimentary, purely sweetening agent two or three 
hundred times as sweet as sugar, is benzoyl-sulphonic imide. Fahl- 
berg obtains it by converting the toluene, C 6 H 5 CH 3 , of coal-tar into 
toluene-sulphonic acid (above) ; this into a calcium salt, then into 
a sodium salt, and the latter into toluene-sulphonic chloride, by 
action of phosphorus trichloride and chlorine ; the liquid orthochlo- 
ride into amide by ammonium carbonate ; the amide is then oxidized 
by potassium permanganate to sulphamidobenzoate and water •, 
hydrochloric acid then precipitating benzoyl-sulphonic imide or 
"saccharin" with elimination of water. "Soluble saccharin" is 
saccharin in which hydrogen is displaced by sodium. The following 
formulae illustrate the stages of manufacture : 

SO <^eH 4 CH 3 s ~ ^C 6 H 4 CH 3 s ~ ^C 6 H 4 CH 3 
BUj ^OH &u 2<^ci &U 2\NH 2 

Toluene-sulphonic Toluene-sulphonic Toluene-sulphonic 
acid. chloride. amide. 

SO ^C 6 H 4 COOK „ n /C 6 H 4 CO ™ ^O.H.CO 
b0 *<NH 2 S °2<NH S0 *<NNa 

Potassium Benzoyl-sulphonic "Soluble 

sulphamidobenzoate. imide, or "saccharin.'' saccharin." 

Sulphonal (B. P.), a new hypnotic, is a crystalline, colorless, 
inodorous, tasteless substance, a product of the action of perman- 
ganate solution on mercaptol — a liquid resulting from the reaction 
20 



446 



ORGANIC CHEMISTRY. 



of hydrochloric acid, mercaptan, and acetone. Its descriptive name 
is diethylsulphon-dimethylmethane, and the following is its descrip- 
tive formula : 



CH3> C <SOAH 5 



S0 2 C 2 H 5 



ETHERS. 

Ethylic (or Ordinary) Ether. —Into a capacious test-tube put 
a small quantity of spirit of wine and about half its bulk of 
sulphuric acid ; mix and gently warm ; the vapor of ether, 
recognized by its odor, is evolved. Adapt a cork and long bent 
tube to the test-tube, and slowly distil over the ether into 
another test-tube. Half the original quantity of alcohol now 
placed in the generating-tube will again give ether ; and this 
operation may be repeated many times. 

On the larger scale, and according to the following official process 
(JEtker, B. P.), the addition of alcohol, instead of being intermit- 
ting, is continuous, a tube con- 
Fig. 41. veying alcohol from a reser- 
<S? voir into the generating-vessel. 
Mix 10 fluidounces of sulphu- 
ric acid with 12 fluidounces 
of rectified spirit in a glass 
retort or flask capable of con- 
taining at least 2 pints, and, 
not allowing the mixture to 
cool, connect the retort or 
flask, by means of a bent glass 
tube, with a Liebig's conden- 
ser, and distil with a heat suf- 
ficient to maintain the liquid 
in brisk ebullition. (If a ther- 
mometer also be inserted in 
the tubulure of the retort or 
through the cork of the flask, 
the temperature may be still 
more carefully regulated— between 284° and 290° F.) . As soon as 
the ethereal fluid begins to pass over, supply fresh spirit in a con- 
tinuous stream, and in such quantity as to about equal the volume 
of the fluid which distils. For this purpose use a tube furnished 
with a stopcock to regulate the supply, as shown in Fig. 41, con- 
necting one end of the tube with a vessel containing the spirit sup- 
ported above the level of the retort or flask, and passing the other 
end through the cork of the retort or flask into the liquid. When 
a total of 50 fluidounces of spirit has been added, and 42 fluidounces 
of ether have distilled over, the process may be stopped. This is 
Miher, U. S. P. 




Preparation of Ether. 



ETHERS. 447 

To partially purify the liquid dissolve 10 ounces of calcium chlor- 
ide in 13 ounces of water, add J an ounce of lime, and agitate the 
mixture in a bottle with the impure ether. Leave the mixture at 
rest for ten minutes, pour off the light supernatant fluid, and 
distil it with a gentle heat until a glass bead of the specific gravity 
0.735 placed in the receiver begins to float. The ether and spirit 
retained by the calcium chloride and by the residue of each rec- 
tification may be recovered by distillation and used in a subsequent 
operation. 

Explanation of Process. — On the addition of sulphuric acid to 
alcohol in equal volumes, one molecule of each reacts and gives a 
molecule of ethylhydrogen sulphate and one of water : 

C 2 H 5 OH + H 2 S0 4 = C 2 H 5 HS0 4 + H 2 0. 

Alcohol. Sulphuric Ethylhydrogen Water, 

acid. sulphate. 

More alcohol then gives ether and sulphuric acid by the reaction 
of one molecule of the alcohol on one of ethylhydrogen sulphate 
(sometimes termed ethylsulphuric acid or sulphethylic acid or sul- 
phovinic acid) : 

C 2 H 5 OH + C 2 H 5 HS0 4 = (C 2 H 5 ) 2 + H 2 S0 2 

Ethyl Ethylhydrogen Ether, Sulphuric 

alcohol. sulphate. or C 2 H 5 — — C 2 H 5 . acid. 

The water of the first reaction and the ether of the second distil 
over, while the sulphuric acid liberated is attacked by alcohol and 
reconverted into ethylhydrogen sulphate. So that the sulphuric acid 
originally employed finally remains in the retort in the form of 
ethylhydrogen sulphate. The effect, however, of a small quantity 
of sulphuric acid in thus converting a large quantity of alcohol into 
ether is limited, secondary reactions occurring to some extent after 
a time. 

Mixed Ethers. — That C 2 H 5 — — C 2 H 5 represents the constitution 
of ether is indicated by the result of the reaction of, say, methyl- 
alcohol on ethylsulphuric acid, a single definite substance, methyl- 
ethyl ether, CH 3 — — C 2 H 5 , resulting. 

Ethers of various radicals, R — — R, and several mixed ethers, 
R a — — R b , and sulphur-ethers, or thio-ethers, R — S — R, are 
known. 

Properties. — Pure ethylic ether is gaseous at temperatures above 
95° F. •, hence the condensing-tubes employed in its distillation must 
be kept as cool as possible. At all ordinary temperatures it rapidly 
volatilizes, absorbing much heat from the surface on which it is 
placed. A few drops evaporated consecutively from the back of the 
hand produce great cold, and if blown in the form of spray the 
cooling effect is so rapid and intense as to produce local anaesthesia. 
Evaporated by aid of- a current of air from the outside of a thin 
narrow test-tube containing water, the latter is solidified to ice. Its 
vapor is very heavy, more than twice and a half as heavy as air, and 
nearly forty times as heavy as hydrogen (H 2 = 2 ; C 4 H 10 O = 74 ; or 
as 1 to 37). In a still atmosphere it will flow a considerable dis- 
tance along a table or floor before complete diffusion occurs. The 



448 ORGANIC CHEMISTRY. 

vapor is highly inflammable ; hence the importance of keeping 
candle and other flames at a distance during manipulations with 
ether. Exposed to the action of air and light, ether becomes charged 
with a little hydrogen peroxide. 

Purification. — To imitate the process of partial purification 
above described, add to the small quantity of ether obtained in 
the foregoing operation a strong solution of calcium chloride 
and a little slaked lime ; the latter absorbs any sulphurous 
acid that may have been produced by secondary decom- 
positions, while the former absorbs water ; on shaking the 
mixture and then setting aside for a minute or two, the ether 
will be found floating on the surface of the solution of cal- 
cium chloride. 

This ether, redistilled until the distillate has a sp. gr. not higher 
than 0.735 and boiling-point not higher than 105° F., is the ether of 
the British Pharmacopoeia. It still contains about 8 per cent, of 
alcohol. The latter may be removed by well shaking the ether with 
half of its bulk of water, setting aside, separating the floating ether, 
and again shaking it with water ; alcohol is thus washed out. This 
washed ether containing water (for water and ether are to some ex- 
tent soluble the one in the other ; 50 measures of pure ether agitated 
with an equal volume of water are reduced to 45 measures) is placed 
in a retort with solid calcium chloride and a little caustic lime, and 
once more distilled ; pure dry ether (uEther Purus, B. P.) results. 
Sp. gr. not exceeding 0.720, indicating about 99 per cent, of real 
ether. Shaken with about a fourth of its bulk of solution of potas- 
sium iodide and a little starch mucilage, little or no blue color is 
produced, indicating absence of an impurity. The exact nature of 
the latter is not known, but inasmuch as it develops hydrogen per- 
oxide, Dunstan and Dymond suggest that the test for the latter 
should always be applied. Poleck and Thummel state that the im- 
purity in ether which causes potash to yield a brown color is vinyl 
alcohol. On shaking pure ether with half its bulk of a dilute solu- 
tion of potassium bichromate acidified by sulphuric acid, and setting 
aside, the supernatant ether has no blue color. 

JEther, U. S. P., contains about 96 per cent, of real ether, and 4 
per cent, of alcohol containing a little water ; sp. gr. 0.725 to 0.728 
at 15° C. ; boiling-point, 37° O, 

Upon evaporation, ether should leave no residue. If 10 cc. of it 
be poured, in portions, upon clean, odorless blotting-paper and 
allowed t© evaporate spontaneously, no foreign odor should become 
perceptible when the last traces of ether leave the paper. When 
20 cc. of ether are shaken in a graduated tube, with 20 cc. of water 
just previously saturated with ether, the ethereal layer, upon sep- 
aration, should not measure less than 19.8 cc. (absence of an undue 
amount of alcohol or water). If 10 cc. of ether be shaken occasion- 
ally, within one hour, with 1 cc. of potassium iodide, no color should 
be developed in either liquid (absence of aldehyde, etc.). — IT. S. P. 

Spiritus JEtheris, U. S. P., is a mixture of 325 cc. of ether with 



ALCOHOLS. 449 

675 cc. of alcohol. Spiritus JEtheris Compositus, U. S. P., contains 
325 cc. of stronger ether, 650 cc. of alcohol, and 25 of ethereal oil. 
It is the old " Hoffmann's Anodyne." 



ALCOHOLS — continued, 

Propylic and Butylic Alcohols. 

The primary and secondary propyl alcohols — C 2 H 5 CH 2 OH and 
(CH 3 ) 2 CHOH— and the four isomeric butyl alcohols (C 4 H 9 OH ; see 
below) are of little pharmaceutical interest. 

CH 2 -CH 2 -CH 3 CH<™3 CH 2 -CH 3 CH 3 

H-C— OH 



I I Wi3 I I 

]_OH H-C-OH CH 3 — C— OH CH 3 — C 

I I I A 



H H H CH 3 

Primary Primary Secondary Tertiary 

normal-butyl iso-butyl butyl butyl 

alcohol. alcohol. alcohol. alcohol. 



Amylic Alcohol. 

Pentylic or Amylic Alcohol (Fousel Oil) (Alcohol Amylicum, B. P.) 
(C 5 H n HO or C 4 H 9 CH 2 OH), is a constant accompaniment of ethylic 
or common alcohol (C 2 H 5 OH), especially when the latter is prepared 
from sugar which has been derived from starch ; hence the name, 
from amylum, starch. The sugar of potato starch yields a consider- 
able quantity ; hence the alcohol is often called potato oil. It is also 
termed fousel oil or fusel oil (from (/>vcj, phuo, to produce), in allusion 
to the circumstance that the supposed oil is not simply educed from 
a substance already containing it, as is usually the case with oils, 
but is actually produced during the operation. It was described as 
oil probably because it resembled oil in not readily mixing with 
water, but it is soluble to some extent in water, and is a true spirit, 
homologous with spirit of wine. It often contains variable propor- 
tions of propylic, butylic, and caprylic alcohols. (See also Valeri- 
anic Acid.) When used for medicinal purposes, " it should be redis- 
tilled, and the product, passing over at 262° to 270° P. (or about 
128° to 132° C), alone be collected for use." 

Amylic alcohol is a "colorless liquid with a penetrating and oppress- 
ive odor and a burning taste. When pure, its specific gravity is 
.818. Sparingly soluble in water, but soluble in all proportions in 
alcohol, ether, and essential oils. Exposed to the air in contact with 
platinum-black, it is slowly oxidized, yielding valerianic acid" 
(C 4 H 9 *COOH). Two allotropic varieties of amylic alcohol exist — 
one, a, having no action on the other, /?, lsevo-rotating a polarized 
ray. The amylic alcohol of trade probably contains both varieties. 



450 ORGANIC CHEMISTRY. 



CH 2 -CH<gH3 CH<™ 2 -CH 3 

H— C— OH H— C— OH CH 3 — C— OH 

H H C 2 H 5 

Primary Primary Tertiary 

a, or inactive j8, or active amylic alcohol, 

amylic alcohol. amylic alcohol. " amylene hydrate." 

The constitution of the variety of amylic alcohol (C 5 H n OH) 
termed tertiary amylic alcohol, or dimethyl-ethylcarbinol, is shown in 
the above graphic formula. It is used in medicine in place of 
chloral hydrate, and is known as amylene hydrate, for it contains 
the elements of amylene (C 5 H 10 ) and water (H 2 0). 

The pentylic salts of pharmaceutical interest are all derived from 
amylic alcohol. 

Other Monhydroxyl Alcohols. 

Among the higher alcohols are the following : 

Cetylic Alcohol (C 16 H 33 OH), or Cetyl Hydrate, formerly termed 
ethal, obtained by saponifying spermaceti (Cetaceum, U. S. P.), 
which consists of cetyl palmitate (C 16 H 33 C 16 H 31 2 ), or cetine. Sperm- 
aceti is the solid crystalline fat accompanying sperm oil in the head 
of the spermaceti whale. 

Cerylic Alcohol (C 27 H 55 OH) is obtained in a similar manner from 
Chinese wax (ceryl cerotate). 

Melissic Alcohol (C 30 H 61 OH) is obtained in a similar manner from 
melissic palmitate, the portion of beeswax soluble in hot alcohol. 
Yellow Wax {Cera Flava, U. S. P.) and the same bleached by 
exposure to moisture, air, and sunlight, or White Wax (Cera Alba, 
U. S. P.), is the prepared honeycomb of the hive-bee. According to 
Brodie, it is in the main a compound of the melissic (C 30 H 61 ) and 
cerotic (C 26 H 53 COO) radicals with about 5 per cent, of ceroleine, the 
body to which the color, odor, and tenacity of wax are due. Amongst 
the possible adulterants of wax are paraffin and ceresine. The latter 
is the purified native ozokerite of Galicia, a solid hydrocarbon, 
largely used as a substitute for beeswax, especially in Russia. Both 
paraffin and ceresine reduce the melting-point of wax, which should 
not be lower than 146° F. (63.3° C.) when taken in the manner 
described in connection with the quantitative determination of tem- 
perature. ( Vide Index.) The amount is obtained by destroying 
the wax with warm oil of vitriol, and afterward with fuming sul- 
phuric acid, which scarcely affects paraffin and ceresine. Pure wax 
will not yield more than about 3 per cent, to cold rectified spirit, 
whereas rosin, etc. would be extracted by the spirit. Solution of 
soda extracts nothing from pure wax, but dissolves fat acids, fat, 
rosin, Japan wax, etc. and the alkaline fluid then yields a precipi- 
tate of acids on the additon of hydrochloric acid. Soap would be 
dissolved from w r ax on boiling the sample with water, and the 
aqueous fluid would yield oily acid on adding hydrochloric acid. 
Flour or any starch would be detected in the cooled aqueous fluid 
by iodine. 



ALCOHOLS. 451 

The Allylic Series of Alcohols (C n H 2n -iOH) (monhydric alcohols). 
— Allylic alcohol (C 3 H 5 *OH) may be obtained by heating 4 parts of 
glycerin with 1 of oxalic acid, the receiver being changed at 195° C, 
and the liquid collected till the temperature rises to 260° C. The 
first product is formic acid, which reacts on glycerin, forming mono- 
formin : 

C 3 H 5 (OH) 3 + HCOOH = OH 2 + C 3 H 5 (OH) 2 (HCOO). 

Glycerin, Formic acid. Monoforinin. 

This, on further heating, yields allylic alcohol : 

C 3 H 5 (OH) 2 HCOO = H 2 + C0 2 + C 3 H 5 OH. 

By the action of the haloid acids it produces iodine, bromine, and 
chlorine derivatives by replacing the OH by I, Br, or CI : these 
derivatives, when digested with potassium sulphocyanate, yield allyl 
sulphocyanate or artificial Oil of Mustard (identical in composi- 
tion with the chief constituent of the natural oil), allyl sulpho- 
cyanate being the body to which mustard owes its power of indu- 
cing inflammatory action on the skin ("Mustard Poultice" and 
Charta Sinapis, U. S. P.). 

Mustard (Sinapis, U. S. P.) is a powdered mixture of black or, 
rather, reddish-brown, mustard-seeds (Sinapis Nigrce Semina, B. P.) 
from the Brassica nigra, and white mustard-seeds (Sinapis Alboz 
Semina, B. P.) from the Brassica alba. The white mustard-seed 
contains sinalbin (C 30 H 44 N 2 S 2 O 16 ), a glucoside which, in contact with 
the myrosin in an aqueous extract of mustard, yields the sulpho- 
cyanate of the radical acrinyl, a body which forms part of the 
essential oil of mustard paste. 

C 30 H u N 2 S 2 O 16 = C 7 H T OCNS + C ]6 H 2 ANSHS0 4 + C 6 H 12 6 

Sinalbin. Acrinyl Acid sinapistne Glucose, 

sulphocyanate. sulphate. 

The black contains the albumen oid ferment myrosin, resembling 
the emulsin of almonds, and also potassium myronate, or sinigrin. 
The latter is the body which, under the influence of the former, 
yields the chief part of the pungent oil of mustard paste. The 
amount of myrosin in black mustard is scarcely sufficient to decom- 
pose the whole of the sinigrin, while in white mustard the amount 
is more than sufficient to decompose the sinalbin. Hence the most 
effective mustard is a mixture of white and black. 

The ferments act most effectively — hence the maximum amount 
of pungency is produced — in mustard paste at temperatures not 
exceeding 100° F. This temperature is contemplated in preparing 
Cataplasma Sinapis, B. P. 

KC 10 H 18 NS 2 O 10 = KHS0 4 + C 3 H 5 CNS + C 6 H 12 6 

Potassium Acid potassium Allyl Glucose, 

myronate. sulphate. isosulphocyanate. 



Crude oil of mustard often contains allyl cyanide, C 3 H 5 CN. 

In the Pharmacopoeia of India the seed of Brassica juncea, Rai, 
or Indian Mustard Plant, is official in addition to that of B. alba and 
B. nigra. It is the common mustard of warm countries. It does 



452 ORGANIC CHEMISTRY. 

not differ chemically from other mustard. Allyl compounds are 
also met with in several other cruciferous and liliaceous plants. Oil 
of Garlic (Allium, U. S. P.) owes its odor to an allyl sulphide 
(C 3 H 5 ) 2 S, some say to a " disulphide." The former may be arti- 
ficially obtained by acting on allyl iodide by potassium sulphide ; 

2C 3 H 5 I + K 2 S = (C 3 H 5 ) 2 S + 2KI 

Allyl Potassium. Allyl Potassium 

iodide. sulphide. sulphide. iodide. 

Decylene Alcohol, C 10 H 19 OH, belongs to this series. Menthol 
[Menthol, B. P.), obtained from oil of peppermint, is said by some 
to consist wholly of this alcohol. 



QUESTIONS AND EXERCISES. 



Give an outline of the relations between alcohols and acids. — Give a 
general method of preparing the primary alcohols of the ethylic series. — 
Name the source of methylic alcohol. — What is "methylated spirit"? — 
Describe the mode of detecting methylated spirit in a tincture. — How 
can artificial ethylic alcohol be prepared ? — Write a few sentences on the 
formation, purification, and concentration of alcohol, and explain the 
difference between rectified spirit, proof spirit, and absolute alcohol. — 
What quantity of water must be added to I gallon of spirit of wine 56 
degrees over proof to convert it into proof spirit ? — How far must 5 pints 
of spirit of wine of 53 degrees over proof be diluted to become proof 
spirit ? — Ans. 7 pints 13 ounces. — State the specific gravity of proof spirit. 
State the proportion of alcohol commonly present in malt liquors, light 
wines, port and sherry, and " spirit," and state the extent to which spirits 
maybe diluted without "adulteration." — Enumerate the characters of 
alcohol. — Whence is brandy obtained? and to what are due its color and 
flavor?— Describe the official process for the preparation of ether, giving 
equations. — Offer a physical explanation of the mode of producing local 
anaesthesia. — How is commercial ether purified ? — Is "amylic alcohol " a 
simple or a complex body ? — How is allylic alcohol prepared ? — In what 
relation does allylic alcohol stand to oil of mustard and oil of garlic? 



Alcohols of the C n H 2n -70H Series. — Phenols and Benzylic Alco- 
hols. — These are alcohols only in the sense of being hydroxyl deriv- 
atives of hydrocarbons. Unlike the paraffin alcohols, they do not 
yield aldehydes, oxidation acids, or ketones. 

Carbolic Acid. 

Phenol, Phenic Alcohol, Phenic Acid, or Carbolic Acid* (C 6 H 5 OH) 
may be artificially obtained by heating benzene with sulphuric acid, 
which forms benzene-sulphonic acid (p. 445), (C 6 H 5 HS0 4 ) this, when 
heated with potash, yielding potassium phenate or carbolate, and 
this, with acids, the phenol: 



* Ordinary carbolic acid is a mixture of phenol, cresol, and other 
homologues. 



CARBOLIC ACID. 453 



C 6 H 5 HS0 3 + 3KH0 = 


= C 6 H 5 OK 


+ K 2 S0 3 + 


2H 2 


Benzene- Potassium 


Potassium 


Potassium 


Water. 


sulphonic acid. hydrate. 


carbolate. 


sulphite. 





Commercially, carbolic acid is obtained from that part of coal-tar 
boiling between 180° and 190° C. When purified, it is a colorless* 
crystalline body (Acidum Carbolicum, U. S. P.). A crystalline, 
so-called hydrous acid (C 6 H 5 OH,H 2 0) may also be obtained. 

At temperatures above 95° F. ordinary carbolic acid is an oily 
liquid. It is only slightly soluble in water, but readily dissolved by 
alcohol, ether, and glycerin (Glyceritum- Acidi Carbolici, U. S. P., 
contains about 20 per cent, of carbolic acid dissolved iu glycerin). 
At 60° F. (15.5° C.) 100 parts of the acid are liquefied by the 
addition of 5 to 10 parts of water (100 of acid and 10 of water 
added forming the Acidum Carbolicum Liquef actum, B. P.)-, dissolve 
30 to 40 of water, and are dissolved by 1800 to 1200 of water, the 
former and latter of these numbers being respectively characteristic 
of the acicular and pulverulent varieties of the acid. In odor, 
taste, and solubility (and in appearance when liquefied by heat or 
by the addition of 5 per cent, of water) it resembles creasote, a 
wood-tar product for which carbolic acid has been substituted. 
Besides phenol (C 6 H 5 OH), coal-tar oil contains cresol, cresylic acid 
(C 7 H 7 OH) or (CgH^CHgOH), the alcohol of toluene, while wood-tar oil 
furnishes guaiacol (C r H 8 2 ) — also a product of the destructive dis- 
tillation of guaiacum resin, boiling-point 200° C. — and creasol 
(C 8 H 10 O 2 ) or creasote. Certain coloring-matters may be obtained by 
the oxidation of carbolic acid : ammonia, or, still better, phenyl- 
ammonia (aniline or phenylamine) mixed with it, and then a small 
quantity of solution of a hypochlorite, gives a blue liquid. No very 
satisfactory chemical method can be found for distinguishing creasote 
from carbolic acid, as creasote contains phenol, the chief difference 
consisting in the fact that the former boils only at 370° F. ; while the 
latter readily dries up at 212°. Some other physical differences 
exist : thus carbolic acid does not affect a ray of polarized light ; 
creasote "twists it slightly to the right. Carbolic acid is either solid 
or may be solidified by cooling ; creasote is not solidified by the cold 
produced by a mixture of hydrochloric acid and sodium sulphate. 
Creasote from coal (impure or crude carbolic acid) gives a jelly 
when shaken with albumen or with collodion ; creasote from wood 
(Creosotum, U. S. P.) is scarcely affected, especially if quite free 
from even all natural traces of carbolic acid. Coal-creasote is solu- 
ble in solution of potash and in the strongest solution of ammonia 
(Read), wood-creasote scarcely soluble. The coal-product is soluble 
in twenty volumes of water, and a neutral solution of ferric chloride 
strikes a more or less permanent green or blue color with the liquid ; 
wood-creasote is less soluble (Aqua Creosoti, U. S. P. ; Creasote- 
water is said to contain 1 in 129) and not permanently colored blue 
by ferric chloride. An alcoholic solution of the coal-creasote is colored 

* Phenol soon assumes a pink color, owing (Fabrini) to the action of 
hydrogen peroxide and ammonia in presence of traces of copper, iron, 
or lead. 

20* 



454 ORGANIC CHEMISTRY. 

brown by ferric chloride, a similar solution of true creasote-green. 
A dilute solution of creasote, such as creasote-water, is not affected 
by agitation with spirit of nitrous ether, while a similar solution of 
phenol becomes red. A few drops of the spirit of nitrous ether are 
placed in a test-tube, then about a drachm of the aqueous fluid, and 
an equal volume of sulphuric acid is poured down the sides of the 
tube. A pink or red color results if phenol be present, especially 
after standing aside a short time (Eykman 5 MacEwan). A solution 
of carbolic acid gives, with excess of bromine-water, an insoluble 
white precipitate of tribromophenol, C 6 H 2 Br 3 OH. This reaction is 
useful in quantitative estimations of carbolic acid. The extent of 
absorption of iodine by alkaline solutions of this and other phenols 
(thymol, naphthol, etc.) serves also for quantitative purposes. Ac- 
cording to Morson, pure creasote is unaffected when mixed with an 
equal volume of commercial glycerin, while carbolic acid is miscible 
in all proportions, and will carry into solution even a considerable 
quantity of creasote. 

Carbolic acid and alkalies yield carbolates or phenylates, as 
C 6 H 5 OK, C 6 H 5 ONa. Alcoholic solutions of the latter and of mercuric 
chloride yield yellow crystalline mercuric phenylate or phenol- 
mercunj (C 6 H 5 0) 2 Hg. 

Carbolic acid is a powerful antiseptic (avri, anti, against, and 
(tj/itg), sepo, to putrefy.) In large doses it is poisonous, antidotes 
being a mixture of olive oil and castor oil, freely administered, 
or a mixture of slaked lime with about three times its weight of 
sugar rubbed together with a little water. Carbolic acid is soluble 
in sulphuric acid, sulphocarbolic acid, phenol-sidphonic acid (C 6 H 4 - 
(OH)S0 3 H), or sulphophenic acid being formed. On diluting and 
mixing with oxides, hydrates, or carbonates sulphocarbolates are 
formed. The formula of sodium sulphocarbolate is NaC 6 H 5 S0 4 2H 2 
or C 6 H 4 (OH)S0 3 Na,2H 2 0. It is obtained by saturating sulpho- 
carbolic acid by barium carbonate, and decomposing the resulting 
soluble barium sulphocarbolate, (C 6 H 4 OHS0 3 ) 2 Ba, by sodium carbon- 
ate until a precipitate of barium carbonate ceases to form. The 
filtrate on evaporation yields colorless, neutral, prismatic crystals of 
the salt (Sodii Sulphocarbolas, or Sodium Sulphocarbolate, U. S. P.), 
the old sulphocarbolate of soda. Sidpliocarbolate of Zinc, (C 6 H 4 - 
OHS0 3 ) 2 Zn,H 2 (Zinci Sidphocarbolas, B. P.), may be obtained by 
saturating sulphocarbolic acid with zinc oxide. 

Trinitro-phenol (C 6 H 2 (N0 2 ) 3 OH) is formed on slowly dropping 
carbolic acid into fuming nitric acid ; it is the yellow dye known as 
carbazotic acid or picric acid; most of the picrates are explosive by 
percussion. 

Both carbolic acid and benzene are secondary products obtained 
in the manufacture of coal-gas ; hence, indeed, the word phenic and 
thence phenyl (from tyaivu, phaino, I light, an allusion to the use of 
coal-gas). 

By heating phenol with zinc dust benzene results : 

C 6 H 5 OH + Zn = ZnO + C 6 H 6 . 
Salicylic acid is made from phenol. ( Vide Salicylic Acid.) 



PHENOL. 



455 



The official test for phenols is a brownish or violet color on the 
addition of a drop of ferric chloride. 

Constitution of Phenol — Phenol (C 6 H 5 OH) may be regarded as 
benzene (C 6 H 6 ) in which one atom of hydrogen (H) is displaced by 
hydroxyl (OH). When two atoms of hydrogen in benzene are dis- 
placed by two of hydroxyl, resorcin (C 6 H 4 20H) results, a colorless, 
crystalline antiseptic having many advantages over carbolic acid in 
surgical operations. Its name was given in allusion to its original 
source, resin, and to certain similarities with orcin. It occurs in 
white flat prisms readily soluble in most liquids. It may be made 
by passing benzol vapor into hot sulphuric acid and heating the 
product (benzenedisulphonic acid, C 6 H 4 (S0 2 'OH) 2 ) with excess of 
soda. 



C 6 H 4 (S0 2 -NaO) 2 


+ 


2NaHO = 


= C 6 H 4 (OH) 2 


+ 2Na 2 -SO, 


Sodium 
euzenedisulphonate. 




Soda. 


Kesorcin. 


Sodium 
sulphite. 



Ortho-, Meta-, and Para-aromatic Compounds. — Resorcin is one 
of a group of three metameric dihydroxyl-benzenes. Their chemical 
relationships warrant the conclusion (on the atomic theory) that the 
cause of their differences in properties is a difference of position of 
the two atoms of hydroxyl in the molecule, these being, respectively, 
next to each other, separated by one atom (of CH), and by two 
atoms (of CH) (see Constitution of Benzene, p. 432), thus : 



C(HO) 



C(HO) 



HC C(HO) 

I II 
HC CH 

V 

CH 

Ortho-dihydroxyl- 
benzene (pyrocatechin). 



HC CH 

I II 
HC C(HO) 

V 

CH 

Meta-dihydroxyl- 
benzene (resorcin). 



HC 

I 
HC 



C(HO) 



CH 



CH 



C(HO) 

Para-dihydroxyl- 
benzene (hydroquinone). 



The foregoing 
lows: 

C 6 H 4 < OH 



formulae may conveniently be shortened as fol- 



C 6 H 4<QH 



(w») 



p tt ^OH 



In these formulae the letters o, m, or p indicate the position of 
the atoms of hydroxyl (OH) in relation to each other : o signifying 
the ortho position of one atom in relation (next, or 1, 2) to the other ; 
m signifying the meta position of one atom in relation (next but one, 
or 1, 3) to the other ; and p signifying the para position of one atom 
in relation (next but two, or 1, 4) to the other. Among the benzene 
or aromatic compounds there are many such metameric trios (three 
xylenes, three phthalic acids, etc.), their occurrence strongly sup- 
porting "the benzene-ring" hypothesis of Kekule as to the consti- 
tution of benzene compounds. 

Cresol, or Tolyl Alcohol, C 6 H 4 OH*CH 3 , one of the alcohols of 
toluene, C 6 H 5 CH 3 , is always found with crude phenol ; artificially 
it may be made in the same manner as phenol, by acting on toluene 
with sulphuric acid and heating the resulting sulphonic acid (C 6 H 4 - 



456 ORGANIC CHEMISTRY. 

(S0 3 H)CH 3 ) with potash. With ferric chloride it gives a brown col- 
oration. The three forms, ortho-, meta-, para-, are known. 

Benzylic Alcohol, Phenylcarbinol, C 6 H 5 CH 2 OH, is isomeric with 
cresol, but has the hydroxyl group replaced in the methane nucleus, 
and not in the benzene nucleus of toluene. Having the CH 2 OH 
group, on oxidation it yields benzoic aldehyde, C 6 H 5 COH (oil of 
bitter almonds), and benzoic acid, C 6 H 5 COOH. 



b. Dihydroxyl Derivatives of Hydrocarbons. 

Dihydric or Dihydroxylic or Diacid Alcohols. — Glycols, C n H 2n - 
(OH) 2 series (see also p. 409). — Glycols may be viewed as dihydroxyl 
derivatives of the paraffins, the alcohols of the ethylic series being 
mono-derivatives : 

C 2 H 6 C 2 H 5 OH C 2 H 4 (OH) 2 

Ethane. Ethyl alcohol. Glycol. 

They are prepared by acting on di-iodo-derivatives of the paraffins 
by silver acetate, and then treating with potash. 

C 2 H 4 I 2 -f 2CH ? COOAg == (CH 3 COO) 2 C 2 H 4 + 2AgI 

Di-iodo-ethane. Silver Ethylene Silver 

acetate. acetate. iodide. 

(CH,COO) 2 C 2 H 4 + 2KHO = C 2 H 4 (OH) 2 + 2CH 3 COOK 

Ethylene acetate. Potash. Glycol. Potassium acetate. 

The glycols yield very interesting results on oxidation, forming 
two sets of acids, the lactic and the succinic series. 

Aromatic Glycols, C n H 2n -8(OH) ? , and Saligenin Alcohols. — Resor- 
cin, pyrocatechin, and hydroquinone are dihydric alcohols of ben- 
zenes. (For their constitution see Phenol.) 

Resorcin. 

Synonyms. — Resorcinol ; Metadioxybenzol. 

It is obtained from various resins (such as galbanum -and asafoet- 
ida), and on a large scale, in the arts, from crude benzene-sulphonic 
acid ; it is purified by sublimation, and finally crystallized from 
benzene. Pesorcinum, U. S. P., is a colorless substance which crys- 
tallizes in rhombic needles or plates, having a peculiar faint odor 
and an unpleasant taste. It is very soluble in water and alcohol, 
also in glycerin and ether, almost insoluble in chloroform. Ferric 
chloride colors the aqueous solution of resorcin a dark violet. If a 
small quantity of tartaric acid be gently heated with a trace of 
resorcin and a few drops of concentrated sulphuric acid, a crimson 
color will be produced, which will become a pale yellow on dilution 
with water. When resorcin is gently heated it should not emit a 
smell of phenol. 

Toluene Dihydric Alcohols — Orcin, C 6 H 3 (OH) 2 CH 3 . This is found 
in lichens. Hydroxybenzylic alcohol, salicylic alcohol, saligenol, 
saligenin, C 6 H 4 OHCH 2 OH. This is obtained from the salicin of 
willow-bark. Having the hydroxyl group in the methane nucleus 



GLYCEKIN. 457 

as well as in the benzene nucleus, salicylic aldehyde (C 6 H 4 OH*COH) 
and salicylic acid (0 6 H 4 OH - COOH) are formed on oxidation. 



c. Trihydroxyl Derivatives of Hydrocarbons. 
Trihydric Alcohols. — C n H 2n -i (OH) 3 series. Glycerols. 

Glycerin. 

Synonyms. — Glycerol j* Propenyl Alcohol ; Glycerin, C 3 H 5 (OH) 3 . 

The propenyl (glycyl or glyceryl) of glycerin, in combination 
with many of the acidulous radicals of the acids, oleic, palmitic, 
stearic, etc., forms most of the solid fats and oils. When these lat- 
ter substances are heated with metallic hydrates (even with water 
— hydrogen hydrate — at a temperature of 500° to 600° F.), double 
decomposition occurs, oleate, palmitate, or stearate of the metal 
is formed, and glycerol (propenyl hydrate) is set free. Hence 
glycerin is a by-product in the manufacture of soap, hard candles, 
and lead plaster. (Vide Index.) 

Properties. — Glycerin is viscid when pure, specific gravity 1.28 
(not below 1.25, U. S. P.), has a sweet taste, and is soluble in water 
or alcohol in all proportions. It has remarkable powers as a solvent, 
is a valuable antiseptic even when diluted with 10 parts of water, 
and useful as an emollient. In vacuo it may be distilled unchanged, 
but under ordinary atmospheric pressure it is decomposed by heat, 
especially if distillation be attempted in a flask or retort. In a 
shallow open vessel heat readily vaporizes it if a little water be 
present. From damp air glycerin absorbs moisture slowly, but in 
considerable proportions. Perfectly pure and anhydrous glycerin, 
at a few degrees below the freezing-point of water, sometimes solid- 
ifies to a mass of crystals. 

Tests. — Heat 1 or 2 drops of glycerin in a test-tube, alone or 
with strong sulphuric acid, 'acid potassium sulphate, or other 
salt powerfully absorbent of water ; vapors of acrolein, acrylic 
aldehyde (from acer, sharp, and oleum, oil), are evolved — 

C 3 H 5 (OH) 3 = 2H 2 + CH 2 CH COH, 

Glycerol. Water. Acrylic aldehyde. 

recognized by their powerfully irritating effects on the eyes 
and respiratory passages. If the glycerin be in solution, the 
latter must be evaporated as low as possible before the test is 
applied. 

To a little weak solution of borax, reddened by the addition 
of phenol-phthalein, add a few drops of the solution (neutral- 
ized, if necessary) suspected to contain glycerin ; if any is 

* It will be noticed that all the alchols have the termination -ol — car- 
binol, glycol, glycerol, saligenol, pyrogallol. 



458 ORGANIC CHEMISTRY. 

present, the color will be discharged, owing to the liberation of 
free boric acid, but will reappear on heating the solution ; this 
reaction is also given by other polyhydric alcohols, such as 
mannite or glucose. 

Add a few drops of the fluid suspected to contain the gly- 
cerin to a little powdered borax ; stir well together ; dip the 
looped end of a platinum wire into the mixture, and expose to 
an air-gas flame ; a deep-green color is produced (Senier and 
Lowe). 

If a very dilute solution of glycerin be mixed with zinc car- 
bonate and then dried at 100° C, and the dried mass extracted 
with absolute alcohol, on evaporation a sweetish residue is left 
behind. This is the official method of detecting glycerin. 

The glycerin liberates boric acid, which colors the flame. (See 
p. 335.) Ammoniacal salts, which similarly affect borax, must first 
be got rid of by boiling with solution of sodium carbonate. Acids 
must also be neutralized. Liquids containing much indefinite 
organic matter must sometimes be evaporated to dryness, the 
residue extracted by alcohol, and the latter tested for the glycerin. 
To detect traces, liquids must be concentrated. 

Glycerin, by action of very strong nitric acid, yields nitro-glycerin, 
or glyceryl nitrate (C 3 H 5 3N0 3 ). It is highly explosive, a very small 
quantity being liable to explode during preparation and with great 
violence. 75 parts of nitroglycerin, absorbed by 25 of porous 
silica, yield a pasty mass more convenient to handle than nitro- 
glycerin itself ; it is used for blasting under the name of dynamite. 
Tablets of chocolate, weighing 1\ grains and containing y^ grain 
of nitroglycerin, constitute the Tabellaz Nitroglycerini, B. P. A " 1 
per cent." solution in rectified spirit (that is, 1 part by weight in 
100 by volume) is the Spiritus Glonoini, or Spirit of Nitroglycerin, 
U. S. P. ; Liquor Trinitrini, B. P. ; Liquor Nitroglycerin^ B. P. ; 
or Liquor Glonoini. The latter solution has a specific gravity of 
0.844, whereas the former solution has a range between 0.826 and 
0.832 at 15° C. 

" If the specific gravity of the spirit be higher than 0.840, or if 
10 cc. of it be rendered turbid by less than 10 cc. of water, the 
spirit should be rejected." 

Besides glycerin itself (Glycerinum, U. S. P.), solutions or mixtures 
of starch and of yolk of egg and glycerin {Glyceritum Amyli, U. S. P., 
Glyceritum Vitelli or Glyconin, U. S. P.) are official. Also Glyceritum 
Acidi Carbolici, U. S. P. ; Glyceritum Acidi Tannici, U. S. P. ; Gly- 
ceritum Boroglycerini, U. S. P. ; and Glyceritum Hydrastis, TJ. S. P. 

Fatty Bodies. 

Processes of Extraction. — Fixed oils and fats are extracted from 
animal and vegetable substances by pressure or straining, with or 
without the aid of heat, or digestion in solvents, as ether, etc., and 
evaporation of the solvent. 



FATTY BODIES. 459 

Constitution and General Relations. — Fixed oils and fats are, 
apparently, almost as simple in constitution as ordinary inorganic 
salts. Just as potassium acetate (KC 2 H 3 2 ) is regarded as a com- 
pound of potassium (K) with the characteristic elements of all 
acetates (C 2 H 3 2 ), so soft soap is considered to be a compound of 
potassium (K) with the elements characteristic of all oleates 
(C 18 H 33 2 ), and hence is chemically termed potassium oleate 
(KC 18 H 33 2 ). Olive oil {Oleum Olivce, U. S. P.), from which soap 
is officially prepared, is mainly oleate of the trivalent radical 
glyceryl (C 3 H 5 ), the formula of such a fluid oil being C 3 H 5 3C 18 H 33 2 , 
and its name oleine. The formation of a soap therefore, on bringing 
together oil and a moist oxide or hydrate, is a simple case of double 
decomposition (or, rather, metathesis), as seen already in connection 
with lead plaster (p. 213), or in the following equation relating to 
the formation of common hard soap : 

3NaHO + C 3 H 5 3C 18 H 33 2 = 3NaC 18 H 33 2 + C 3 H 5 3HO 

Sodium hydrate Glyceryl oleate Sodium oleate Glyceryl hydrate 

(caustic soda). (vegetable oil). (hard soap). (glycerin). 

Berthelot has succeeded in preparing oil artificially from hydrogen 
oleate or oleic acid, HC 18 H 33 2 , and glycerin, and it is said to be 
identical with the pure oleine of olive oil and of other fixed oils. 

Olive oil is liable to contain cotton-seed oil. The admixture may 
be detected by Bechi's test: Take 1 grain of crystallized silver 
nitrate and dissolve it in the smallest possible quantity of water 
(about 1 cc), and add 200 cc. of alcohol (96°). The addition also 
of 20 cc. of sulphuric ether is a good one, in that it makes the 
reagent better miscible with the oil to be examined, but it is not 
necessary. On the other hand, prepare a solution composed of 85 
parts of amylic alcohol and 15 parts of oil of rape-seed. These 
reagents should be made as needed, and not kept on hand for any 
length of time. To apply the test, take 10 cc. of the oil to be 
examined, add 1 cc. of the alcoholic solution of silver nitrate, and 
then from 8 to 10 cc. of the mixture of amylic alcohol and oil 
of rape, agitating strongly and then heating on a water-bath for 
five or ten minutes. In the case of pure oils the color remains the 
same as it was after the addition of the reagents. If cotton-seed 
oil be present, there will be produced a brownish color or turbidity 
of a varying grade, from a very light brown to a deep maroon or 
black, according to the quantity of cotton oil present. 

Hard fats chiefly consist of stearine — that is, of tristearate of 
glyceryl (C 3 H 5 3C 18 H 35 2 ). Mr. Wilson, of Price's Candle Company, 
obtains stearic and oleic acids and glycerin by simply passing steam, 
heated to 500° or 600° F., through melted fat. Both the glycerin 
and fat-acids distil over in the current of steam, the glycerin dis- 
solving in the condensed water, the fat-acids floating on the aqueous 
liquid. From glyceryl oleate and hydrogen hydrate there result 
hydrogen oleate and glyceryl hydrate.* The oleic acid (Acidum 

* Any such decomposition of water and fixation of its elements, 
whether direct as above, or indirect through the intermediate agency of 
saponification, is termed hydrolysis (vSo>p, hudor, water, Avw, luo, to decom- 



460 ORGANIC CHEMISTRY. 

Oleicum, U. S. P.) is separated by cooling and pressing the mixture. 
It is " a straw-colored liquid, nearly odorless and tasteless, and with 
not more than a very faint acid reaction. Unduly exposed to air, it 
becomes brown and decidedly acid. Specific gravity, 0.860 to 0.890. 
It is insoluble in water, but readily soluble in alcohol, chloroform, 
and ether. At 40° to 41° F. (4.5° to 5° C.) it becomes semi-solid, 
melting again at 56° to 60° F. (13.3° to 15.5° C). It should be 
completely saponified when warmed with potassium carbonate ; and 
an aqueous solution of this salt, neutralized by acetic acid and 
treated with lead acetate, should yield a precipitate which, after 
washing with boiling water, is almost entirely soluble in ether," 
showing the absence of any important quantity of stearic and 
palmitic acids, the lead stearate and palmitate being insoluble in 
ether. 

In a mixture of oils or fats and free fatty acids the latter may be 
estimated by taking advantage of their solubility in spirit of wine, 
and the formation of a neutral soap on shaking the spirituous solution 
with caustic soda, phenolphthalein being used as indicator. (See 
the section on the use of the caustic-soda solution in Volumetric 
Analysis.) 

The author found (Pharmaceutical Journal, March, 1863) that 
oleic acid readily combines with alkaloids and most of the metallic 
oxides or hydrates, forming oleates which are soluble in fats. In 
this way active medicines may be administered internally in con- 
junction with oils or externally in the form of ointments (Oleatum 
Hydrargyria U. S. P., and Oleatum Zinci, U. S. P. ; Oleatum Vera- 
trince, U. S. P.). Tichborne considers the formula of mercuric oleate 
to be Hg(C 18 H 33 2 ) 2 H 2 0. 

Some fats, such as " suint" from sheep's wool and the unctuous 
matter from bristles, feathers, horn, and hair generally, yield by 
saponification, etc. fatty acids, and, instead of glycerin, cholesterin, 
an alcoholoid crystalline substance. The " lanolin" of pharmacy 
is cholesterin fat which has absorbed a large volume of water. 

Adeps Lance, or Wool Fat, B. P., is u the purified cholesterin fat 
of sheep's wool." It is " a yellowish, tenacious, unctuous substance ; 
almost inodorous, with a melting-point varying from 100° F. (37.8° C.) 
to 112° F. (44.4° C.) ; readily ^soluble in ether and in chloroform, 
sparingly soluble in rectified spirit. 10 grains should dissolve almost 
completely in 14 fluidrachms of boiling ethylic alcohol, the greater 
part separating in flocks on cooling. Ignited with free access of 
air, it burns, leaving but a trace of ash. 50 grains dissolved in 4 
fluidrachms of ether and 2 drops of tincture of phenolphthalein 
added, should not require more than 2 grain-measures of vol- 
umetric solution of soda to produce a permanent red coloration. 
The solution in chloroform poured gently over the surface of sul- 
phuric acid acquires a purple-red color. Heated with solution of 
soda, no ammoniacal odor should be evolved." 

Adeps Lance Hydrosus, or Hydrous Wool Fat, U. S. P., is "the 

pose). The fixation of water without such actual separation of its ele- 
ments from each other is termed hydration. 



soaps. 461 

purified fat of the wool of sheep, mixed with not more than 30 per 
cent, of water. 1 ' It is commonly known as " lanoline." It is a 
" yellowish-white or nearly white ointment-like mass, having a 
faint, peculiar odor ;" has a melting-point about 104° F. (40° C). 

Hydrous wool fat is insoluble in water, but mixes with twice its 
weight of it, dissolves with turbidity in ether and chloroform to 
form a neutral solution. When heated on a water-bath it leaves 
a residue of not less than 70 per cent., which should be completely 
soluble in ether and chloroform, and only partially so in alcohol ; 
should give the same reactions as wool fat. " If 10 grm. of hydrous 
wool-fat be heated, together with 50 cc. of water, on a water-bath 
until the fat is melted, there should result an upper, translucent, and 
light-yellow, fatty layer, and a lower, clear, aqueous layer, which 
latter should not yield glycerin upon evaporation." — U. S. P. 

Soaps. 

Olive oil boiled with solution of potash yields potassium soap, or 
soft soap (Sapo Mollis, U. S. P., or Green Soap) ; with soda, sodium 
soap, or hard soap (Sapo, U. S. P.), or white Castile soap, as distin- 
guished from the variety of hard Castile or Marseilles soap, which 
is "mottled" by iron 5 soap mixed with ammonia, an ammonium 
soap (Linimentum Ammonias, U. S. P.) ; and with lime-water, cal- 
cium soap (Linimentum Calais, U. S. P.), — all oleates, chiefly of the 
respective basylous radicals. Their mode of formation is indicated 
in the equation on p. 459. The alkali soaps are soluble in alcohol, 
the others insoluble. A green soap, much used on the continent of 
Europe, and indeed official in Germany (formerly as Sapo Viridis, 
now as Sapo Kalinus Venalis), is made by adding indigo to ordinary 
soft soap, the yellow color of the soap yielding with the indigo 
a greenish compound. The official characters of hard soap are — 
"grayish-white, dry, inodorous; horny and pulverizable when kept 
in dry warm air ; easily moulded when heated ; soluble in rectified 
spirit ; not imparting an oily stain to paper ; incinerated, it yields 
an ash which does not deliquesce-," and of soft soap — "yellowish- 
green, inodorous, of a gelatinous consistence ; soluble in rectified 
spirit ; not imparting an oily stain to paper : incinerated, it yields 
an ash which is very deliquescent." Curd soap (Sapo Animalis, 
B. P.) is " a soap made with soda and a purified animal fat, con- 
sisting principally of stearine." It will, of course, chiefly contain 
sodium stearate. In pharmacy it is often advantageously employed 
instead of the "hard soap." 

The hard soap met with in trade is made from all varieties of oil, 
the commoner kinds being simply the product of the evaporated 
mixture of oil and alkali, while the better sorts have been separated 
from alkaline impurities and the glycerin by the addition of com- 
mon salt or excess of lye to the liquors, which causes the precipita- 
tion of the pure soap as a curd. Potash soap is not so readily pre- 
cipitable by salt ; moreover, some soda soap results. Saponification 
on the small scale is much facilitated by first well mixing the oil 
with 5 per cent, of sulphuric acid, and letting this mixture stand 
for twenty-four hours. The dark product is then readily soluble 



462 ORGANIC CHEMISTRY. 

when boiled with soda, and the clear fluid yields a crust of white 
soap on cooling. If required quite free from alkali, the resulting 
soap is boiled with water until dissolved, salt added, and the whole 
cooled. A cake of pure soap results. 

Yellow soap is a common, cheap soap, containing a good deal 
of resin soap, resin consisting chiefly of acids — pinic, sylvic, 
pimaric, etc. — which readily unite with alkalies to form true 
soaps. 

Saponification. — This term is now extended in chemistry so as 
to include any process analogous to the foregoing — any reaction in 
which an alkali decomposes any ethereal salt or alkyl salt. 

Solid Fats. 

1. Lard (Adeps, U. S. P.) is the purified internal fat of the abdo- 
men of the hog — the perfectly fresh omentum or flare, freely exposed 
to the air to dissipate animal odor, rubbed to break up the mem- 
branous vesicles, melted at about 130° F. (54*4° C), and filtered 
through paper or flannel. Lard Oil (Oleum Adipis, U. S. P.), which 
is chiefly olein, is a " fixed oil expressed from lard at a low tempera- 
ture." Sp. gr. 0.90 to 0.920 at 15° C. 2. Benzoinated Lard (Adeps 
Benzoinatus, U. S. P.) is prepared lard heated over a water-bath with 
benzoin (1 part to 50), which communicates an agreeable odor and 
prevents or retards raneidity. Purified lard is a mixture of oleine 
(lard oil, removable by pressure) and stearine. Margarine, formerly 
supposed to be a constituent of lard and other soft fats, is now 
regarded as a mere mixture of palmitine (the chief fat of palm oil) 
and stearine. 3. Suet, the internal fat of the abdomen of the sheep, 
purified by melting and straining, forms the official Sevum, U. S. P. ; 
it is almost exclusively composed of stearine (C 3 H 5 3C 18 H 35 2 ). 
4. Expressed Oil of Nutmeg (Oleum Myristicce Expressum, B. P.), 
commonly but erroneously termed Oil of Mace, is a mixture of a 
little volatile oil with much yellow and white fat ; the latter is 
myristin or myristate of glyceryl (C 3 H 5 3C 14 H 27 2 ). 5. Oil of Tlieo- 
broma, or Cacao Butter (Oleum Theobromatis, U. S. P.), chiefly 
stearine, but with one higher and some lower homologues (Heintz), 
is a solid product of the roasted and crushed seeds or cocoa-nibs of 
Theobroma cacao. They contain from one-half to two-thirds of this 
fat. [Cocoa is too rich for use as food, hence is diluted with farina 
(cheap cocoa) or sugar (chocolate) or has a portion of its fat extracted, 
while its solubility is, in one brand, usefully increased by a slight 
addition to its potassium.] 6. Cocoa-nut Oil, or butter, a soft fat 
contained in the edible portion of the nut of Cocos nucifera, or cocoa- 
nut of the shops, is a body containing glyceryl united with six 
acidulous radicals — namely, the caproic (C 6 H n 2 ), caprylic (C 8 H 15 2 ), 
rutic (C 10 H ]9 O 2 ), lauric (C 12 H 23 2 ), myristic (C u H 27 2 ), and palmitic 
(Ci 6 H 31 2 ) — radicals which, like some from resin, when united with 
sodium, form a soap differing from ordinary hard soap (sodium 
oleate) by being tolerably soluble in a solution of sodium chloride; 
hence the use of cocoa-nut oil and resin in making marine soap, a 
soap which, for the reason just indicated, readily yields a lather in 
sea-water. 7. Kokum Butter, Garcinia Oil, or Concrete Oil of 



FIXED OILS. 463 

Mangosteen, a whitish or yellowish-white fat obtained from the seeds 
of Garcinia Indica or G. purpurea, is composed of stearine, myristi- 
cine, and oleine. It is recognized officially in the Pharmacopoeia of 
India (Garcinice Purpureas Oleum). 

Butter commonly yields 87J per cent, of insoluble fat acids by 
saponification and decomposition of the soap by acid. Other animal 
fats, with which butter is likely to be adulterated, yield about 95^. 
Hence the percentage of fat acids, and, especially, volatile acids, 
insoluble acids, and soluble acids, yielded by a suspected sample of 
butter, indicates purity or the opposite. Occasionally, however, a 
sample of genuine butter may not conform to the figures, hence 
they cannot be relied on to show the exact extent of sophistication. 

Fixed Oils. 

Fixed and volatile oils are naturally distinguished by their 
behavior when heated ; they also generally differ in chemical constitu- 
tion- — a fixed oil being, apparently, a combination of a basylous with 
an acidulous radical, as already stated, while a volatile oil is more 
commonly a neutral or normal hydrocarbon, mixed with a compara- 
tively small proportion of a body — containing oxygen as well as car- 
bon and hydrogen — to which the odor of the oil is generally due. 
The latter bodies are now articles of trade under the name of " con- 
centrated essential oils." 

Drying and Non-drying Oils. — Among fixed oils, most of which 
are oleate with a little palmitate and stearate of glyceryl, a few, such 
as — 1, Linseed Oil (Oleum Lini, U. S. P., contained in linseed or 
flaxseed, the ground residue of which " should yield, when extracted 
with disulphide of carbon, not less than 25 per cent, of fixed oil," is 
linseed meal), and, 2, Cod-liver Oil (Oleum Morrhuce, U. S. P.), and, 
to some extent, castor and croton, are known as drying oils, from the 
readiness with which they absorb oxygen and become hardened to a 
resin. Linseed commonly contains 37 or 38 per cent, of oil ; 25 to 
27 per cent, is obtained by submitting the ground seeds to hydraulic 
pressure, 10 to 12 percent, remaining in the residual oil-cake. Boiled 
oil is linseed oil which has been boiled with lead oxide. This treat- 
ment increases the already great tendency of linseed oil to resinify, 
forming linoxyn (C 32 H 54 O n ) on exposure to air. The drying oils 
appear to contain linoleine, an oily body distinct from oleine. Cod- 
liver oil contains an unimportant trace of iodine, 1 in 1 ,000,000 or 
2,000,000 parts, according to Stanford ; a little choline also and other 
bases, Gautier and Mourgues having recently isolated aselline, 
C 25 H 32 N 4 , and morrhuine, C 19 H 27 N 3 , besides butyl-, amyl-, and hexyl- 
. amines and dihydro-lutidine. Among the non-drying oils are 
the following: 3. Almond Oil (Oleum Amygdaloz Expressum, 
U. S. P.), indifferently yielded by the bitter (Amygdalae Amara, 
U. S. P.) or sweet seed {Amygdalae Dulcis, U. S. P.) to the extent 
of 45 and 50 per cent, respectively. (3a) Cotton-seed Oil {Oleum 
Gossypii Seminis, U. S. P.) contains oleine and some palmitine. Sp. 
gr. 0.920 to 0.930. It should not be permanently colored dirty-yellow 
by sulphuric acid. 4. Croton Oil { Oleum Crotonis, B. P., and Oleum 
Tiglii, U. S. P.). Gleuther states that no such acid as crotonic is 



464 ORGANIC CHEMISTRY. 

obtainable from croton oil, but acetic, butyric, valerianic, and higher 
members of the oleic series, together with tiglic acid, HC 5 H 7 2 . H, 
Senier states that alcohol separates croton oil into a soluble oil con- 
taining the powerful vesicating principle of croton oil and an insolu- 
ble non-vesicating but powerful purgative principle. Robert states 
that free crotonoleic acid is both the vesicant and the purgative. 

5. Lycopodium (U. S. P.), a yellow powder composed of the spores 
of the common club-moss {Lycopodium clavatum), contains a large pro- 
portion of a very fluid fixed oil ; also an alkaloid (Bodeker) , C 32 H5 2 N 2 3 . 

6. Olive Oil {Oleum Olivce, U. S. P.), already noticed (p. 459). " If 
1 grm. of olive oil be agitated in a test-tube with 2 grm. of cold 
mixture prepared from equal volumes of strong sulphuric acid and 
of nitric acid of sp. gr. 1.18.5, and the mixture be set aside for half 
an hour, the supernatant oily layer should not have a darker tint 
than yellowish, nor should a green or red layer separate on stand- 
ing if 1 grm. of the oil be shaken for a few seconds with 1 grm. of a 
cold mixture of sulphuric acid (sp. gr. 1.830) and nitric acid (sp. gr. 
1.250), and 1 grm. of carbon disulphide ; and if 5 drops of the oil are 
let fall upon a thin layer of sulphuric acid in a flat-bottomed capsule, 
no brown-red or dark-brown zone should be developed within three 
minutes at the line of contact of the two liquids (absence of appre- 
ciable quantities of other fixed oils of similar physical properties)." — 
U. S. P. 7. Castor Oil ( Oleum Bicini, U. S. P.), chiefly a ricin- 
oleate of glyceryl (C 3 H 5 3C 18 H3 3 3 ) or ricinoleine, a slightly oxidized 
oleine, soluble, unlike most fixed oils, in alcohol and in glacial acetic 
acid. Castor-oil seeds were stated, by Tuson, to contain an alka- 
loid, ricinine. Beck has recently confirmed Tuson, giving as the 
formula C 24 H 32 N 7 3 . It possesses no purgative property. They also 
contain an albumose, ricin, resembling, physiologically, but not 
quite chemically, the abrin of jequirity. 8. Oil of Male Fern {Filix 
Mas, B. P.), a vermifuge obtained by exhausting the rhizome 
(Aspidium, U. S. P.) with ether and removing the ether by evapora- 
tion — a dark-colored oil containing a little volatile oil and resin, and 
officially termed an oleoresin {Oleoresina Aspidii, U. S. P.). Its 
chief active constituent appears to be filicic acid, C 35 H 42 13 . 9. Fixed 
Oil of Mustard, a bland, inodorous, yellow or amber oil yielding, by 
saponification and action of sulphuric acid, glycerin, oleic acid, and 
erucic acid (HC 22 H 41 2 ) (Darby). 10. Arachis Oil {Oleum Arachis, 
P. I.) is found to the extent of 40 or 50 per cent, in the seeds of the 
Arachis hypogcea (P. I.), the ground-nut or earth-nut (so called 
because the pod of the herb in the growth of its stalk downward is 
forced beneath the surface of the ground and there ripens). It is 
chiefly oleine, but contains hypogseine, palmitine, and arachine. 
The oil is largely used in India in the place of olive oil, and is becom- 
ing much employed in Europe, especially for soap-making. 11. Sesame 
Oil, or Oil of Sesamum {Oleum Sesami, U. S. P.) (Gingelly, Teal, or 
Benne Oil), from the seeds of Sesamum indicium, is also largely 
used in Europe. It has most of the characters of the best olive oil. 
It may be detected in olive oil by shaking the sample with a solu- 
tion of pyrogallic acid in strong hydrochloric acid, and separating 
and boiling the acid fluid, a purplish color resulting if sesame be 



MANNITE. 465 

present. 12. Shark-liver Oil, from Squalus carcharias (Oleum 
Squalce, P. I.), is used as a substitute for cod-liver oil in India. 



Trihydric Alcohols of the C n H 2n _ 9 (OH) 3 series. 
Pyrogallol or Pyrogallic Acid. — Trihydroxybenzene, C 6 H 3 (OH). v 
( Vide Index.) 

d. Other Polyhydroxyl Derivatives of Hydrocarbons. 

Only one tetrahydric alcohol is known — namely Erythrite, or Lichen 
Sugar, C 4 H 6 (OH) 4 , found in Protococcus vulgaris, Roccella tinctoria, 
and P. fuciformis. Quercite, the sugar of acorns, is penthydric ; 
Mannite is hexahydric. Sorbite occurs in the fruits of the order 
Rosacea?. 

Hexahydric Alcohols. — Mannite, C 6 H 8 (OH) 6 . — Boil manna 
with 15 or 16 parts of alcohol, filter, and set aside ; mannite 
separates in colorless shining crystals or acicular masses to the 
extent of from 60 to 80 per cent, of the manna. It is closely 
related to the ordinary sugars, glucose becoming mannite by 
action of nascent hydrogen : 

C 6 H 12 6 + H 2 = 6 H u O 6 

Glucose. Hydrogen. Mannite. 

Mannite does not undergo fermentation in contact with yeast. 
With nitric acid it forms explosive nitromannite, C 6 H 8 (N0 3 ) 6 . 

Manna, TT. S. P., is a concrete saccharine exudation obtained 
by making transverse incisions in the stems of cultivated trees 
of Fraxinus Ornus. It occurs in stalactitic pieces, varying in 
length and thickness, flattened or somewhat concave on their 
inner surface, and of a pale yellowish-brown color, and nearly 
white externally. This manna, which is known as flake manna, 
is crisp, brittle, porous, crystalline in structure, and readily sol- 
uble in about 6 parts of water. Odor faint, resembling honey ; 
taste sweet and honey-like, combined with a slight acridity and 
bitterness. It contains about 10 per cent, of moisture. Man- 
nite is also met with in celery, onions, asparagus, certain fungi 
and sea-weeds, occurs in the exudations of apple and pear 
trees, and is produced during the viscous fermentation of sugar. 

Dulcite, isomeric with mannite, is formed by the action of nascent 
hydrogen on inverted milk-sugar. It differs from mannite by 
oxidizing to mucic acid, C 6 H 10 O 8 , when treated with nitric acid. 



. QUESTIONS AND EXERCISES. 

How is phenol artificially and commercially prepared?- -How would 
you distinguish carbolic acid from creasote? — Give the formulae and 



466 ORGANIC CHEMISTRY. 

systematic names for picric acid, sodium carbolate, and resorcin. — Give 
names for the bodies having the formulae C6H4OHCH3 and C6H5CH2OH. 
— What are glycols? how prepared? — Give formula and mention the 
chief properties of glycerin. — What is the specific gravity of glycerin ? — 
By what test is glycerin recognized? — Enumerate some official prepara- 
tions in which glycerin is employed. Give a sketch of the general 
chemistry of fixed oils, fats, and soaps. — What is the difference between 
hard and. soft soap? — Which soaps are official? — Name the source of lard. 
— How is " Prepared Lard " obtained ? — Mention the chief constituent of 
suet. — Whence is cacao-butter obtained? — Why is marine soap so called? 
and from what fatty matter is it almost exclusively prepared ? — What do 
you understand by drying and non-drying oils? — In what respect does 
castor oil differ from other oils ? — How is oil of male fern (Ex. Filicis 
Liquidum) prepared? — Classify pyrogallol (pyrogallic acid), erythrite, 
mannite, and dulcite. — Describe the source and characters of manna. 



CARBOHYDRATES. 



Under the name carbohydrates have been grouped a large number 
of compounds containing carbon with hydrogen and oxygen in the 
same proportion as in water, and whose constitution has only re- 
cently been understood. They include sugars, dextrin, starch, cel- 
lulose, etc. The molecules of some of the latter are very complex, 
but are resolved by hydrolysis into sugars such as glucose. 

The most commonly occurring carbohydrates contain six carbon 
atoms or even multiples of that number, but analogous bodies with 
three, five, seven, or nine carbon atoms in the molecule have lately 
been discovered. 

The sugars are the simplest of the carbohydrates in constitution, 
and a large number of them, some identical with previously known 
natural sugars, some previously unknown, have been synthesized. 
They are partially oxidized polyhydric alcohols, having one of their 
alcohol groupings oxidized into an aldehyde or ketone group. For 
example, the trihydric alcohol glycerin, on gentle oxidation with 
bromine, yields a body, glycerose, having all the characters of a 
sugar. 

H H H H H h 

HC-C-CH + = HC— C-C<^ + H 2 
OOO - a 

H H H H H 

This, however, is not stable, but spontaneously condenses into a 
glucose, C 6 H 12 6 . 

Urythrose, C 4 H 8 4 , is an example of a sugar with four, and ara- 
binose, C 5 H 10 O 5 , of one with five, atoms of carbon. Most of the nat- 
ural sugars are glucoses (C 6 H 12 6 ) or compounds of two or three 
molecules of glucoses minus water (Moses or trioses). 

Sugars with seven, eight, and nine atoms of carbon have been 
constructed by treating glucoses with hydrocyanic acid, which com- 
bines with the aldehyde or ketone group to form -the nitrite of an 
acid containing one more carbon atom. This on hydrolysis gives 
the acid, the lactone of which may be reduced to the corresponding 



GLUCOSES. 467 

sugar by the action of nascent hydrogen. This process is then 
repeated to get an eight-carbon sugar, and so on. One of these 
seven-carbon sugars was found to be identical with a natural sugar, 
perseite, but most of them have not yet been found occurring nat- 
urally. 

Glucoses, C 6 H 12 6 . 

Glucoses, C 6 H 12 6 . — There are two chief types of these six-carbon 
sugars, differing from each other in the position of the alcohol 
grouping that has undergone oxidation, and classed accordingly as 
aldehyde and ketone sugars — aldose and ketose. Dextrose is an 
example of the first, and Icevulose or fructose of the second class. 
Each of these classes contains a very large number of physical 
isomers, differing from each other in their action on polarized light 
and in some other respects ; these may be most readily distinguished 
from one another by means of the physical characters of the com- 
pounds they form with phenyl-hydrazine. (See Index.) The large 
number of these isomers is accounted for, on the stereo-chemical 
theory, by the circumstance of there being no less than four asym- 
metrical carbon atoms in each molecule. Thus there are three dex- 
troses — dextro-rotatory, laevo-rotatory, and inactive ; three analogous 
mannoses ; three fructoses or laevuloses, etc. Ordinary lsevulose, 
or, better, fructose, is not, therefore, the mere optical isomer of 
dextrose, each of them having dextro-, laevo-, and inactive forms. 

All the glucoses above mentioned have been obtained artificially, 
the starting-point being an artificial glucose (or acrose, C 6 H 12 6 ) 
obtained by the condensation of formic aldehyde, CH 2 0(6CH 2 = 
C 6 H 12 6 ) ; it is probably in a similar way that natural sugars are 
produced by plants. 

Dextrose, or Grape-sugar, or Glucose (from ylvuvc, glucus, sweet), 
is often seen in the crystallized state in dried grapes or raisins and 
other fruits ; it is also the variety of sugar met with in diabetic 
urine. Its crystalline character is quite distinct from that of cane- 
sugar, the latter forming large four- or six-sided rhomboidal prisms, 
while grape-sugar occurs in masses of small cubes or square plates. 
Grape-sugar is also less soluble in water, but more soluble in alcohol, 
than cane-sugar. 

According to Fresenius, the percentage proportion of saccharine 
matter in the dried fig is 60 to 70 ; grape, 10 to 20 ; cherry, 1 1 ; 
mulberry, 9 ; currant, 6 ; whortleberry, 6 : strawberry, 6 : raspberry 
(Rubus Idceus, U. S. P.), 4. 

Fructose or Icevulose is lgevogyrate, while sucrose and glucose pos- 
sess right-handed rotation ; the latter twist a ray of polarized light 
from left to right to an extent dependent on the amount of sugar 
present — a fact easy of application in estimating the amount of 
sugar in syrups or in diabetic urine. 

Fructose or Icevulose is the uncrystallizable or very difficultly crys- 
tallizable constituent of inverted cane-sugar. It is found in the 
grape, fig (Ficus, U. S. P.), cherry, gooseberry, strawberry, peach, 
plum, and other fruits, often with dextrose or with cane-sugar. 
Fruit-sugar reduces cupric salts and silver ammonio-nitrate. 



468 ORGANIC CHEMISTRY. 

Artificial Formation of Grape-sugar from Cane-sugar Tests 

for Sugar. — Dissolve a grain or two of common cane-sugar in 
water. To a portion of this solution placed in a test-tube add 
more water, two or three drops of solution of copper sulphate, 
a considerable quantity of solution of potash or soda (enough 
to turn the color of the liquid from a light to a dark blue), 
and heat the mixture to the boiling-point ; no obvious imme- 
diate change occurs. To another portion of the syrup add a 
drop of sulphuric acid, and boil for ten or twenty minutes ; 
then add the copper solution and alkali, and heat as before ; a 
yellowish-red precipitate of cuprous oxide (Cu 2 0) falls. This 
test is exceedingly delicate. 

The above reaction is due to the conversion of the cane-sugar 
(C ]2 H 22 O n ) into inverted sugar — or l&vulose, C 6 H 12 6 (so called because 
its solution causes left-handed rotation of a ray of polarized light, 
cane-sugar having an opposite effect) and grape-sugar, C 6 H 12 6 ,H 2 
— by the influence of the sulphuric acid, and to the reducing action 
of the laevulose and grape-sugar on the cupric solution. The forma- 
tion of a precipitate immediately, without the action of acid, shows 
the presence of the latter sugars — its formation only after ebullition 
with acid indicating, in the absence of starch or dextrin, cane-sugar. 
In this reduction-process the sugar is oxidized and broken up into 
several substances, but the exact nature of the reaction has not been 
ascertained. 

Dextrin also reduces the copper salt to suboxide, unless its solu- 
tion is cold and very dilute. It does not, however, so act on a solu- 
tion of cupric acetate acidified with acetic acid, while glucose produces 
with this liquid the usual red cuprous precipitate (Barfoed). 

Sugar from Starch. — Boil starch with a little water and a 
drop of sulphuric acid as for dextrin, but continue the ebulli- 
tion for several minutes ; on testing a portion of the cooled 
liquid with iodine and another portion with the heated alka- 
line solution of a copper salt, as described above, it will be 
found that the starch has nearly all become converted into a 
sugar — dextrose. Maltose is also formed, at first, but by the 
continued action of the acid is changed to dextrose. When 
made on a large scale a warm (131° F.) mixture of starch and 
water of the consistence of cream is slowly poured into a boil- 
ing solution of 1 part of sulphuric acid in 100 of water, the 
whole boiled for some time, the acid neutralized by chalk, the 
mixture filtered, the liquid evaporated to a thick syrup ^nd set 
aside ; in a few days it crystallizes to a granular mass resem- 
bling honey. In this operation a small quantity of dextrin 
remains with the glucose ; but if the process be conducted 
under pressure, conversion, according to Manbre, is complete. 
Sugar made from the starch of rice, maize, etc. is largely used 



SACCHAROSES. 469 

for table syrups, confectioneries, bee-food, and as a partial sub- 
stitute for malt in brewing. It is known as patent sugar, sac- 
charine, maltose, etc. 

In the United States the dealers term the syrups "glucose," and 
the further evaporated solid product "grape-sugar." The former 
contain one-third or more of dextrose, about one-fifth of maltose, 
one-fourth or more of dextrin, and about one-sixth or one-fifth of 
water ; the latter often contain about three-fourths of dextrose, from 
none up to one-third of maltose, and one-seventh or one-sixth of 
water. 

Galactose (from milk-sugar), Sorbinose (from mountain-ash ber- 
ries), Inosite (from muscles), Mannose, (from mannite), Gulose, For- 
mose, fi-acrose, Rhamnose, Dambose (from a caoutchouc), and Scyllite 
(from many fish), are other glucoses. 

Saccharoses, or Bioses, C 12 H 22 O u . 

Cane-sugar, or Sucrose (Saccharum Puriftcatum, U. S. P.), is a 
frequent constituent of vegetable juices. Thus it forms the chief 
portion of cassia-pulp (Cassias Pulpa, U. S. P.), is contained in the 
carrot and turnip, but is most plentiful in the sugar-cane ; much, 
however, is now obtained from the sugar-maple and beet-root. On 
evaporation of the juice common brown or moist sugar crystallizes 
out ; this by re-solution, filtration through animal charcoal, evapor- 
ation to a strong syrup, and crystallization in moulds, yields the 
compact crystalline conical loaves known in trade as lump sugar. 
From a slightly less strong syrup, slowly cooled, the crystals termed 
sugar-candy are deposited, white or colored, according to the color 
of the syrup. The official syrup (Syrupus, U. S. P.) is an aqueous 
solution, consisting of 85 grammes of sugar, dissolved in water and 
made up to 100 cc. 

The sugar in fresh fruits is mainly cane-sugar, but by the action 
of the acid, or possibly of a ferment in the juice, it is gradually 
converted into inverted sugar, a variety differing from cane-sugar in 
being uncrystallizible, and in having an inverted or opposite influ- 
ence on polarized light, twisting the ray from right to left (laevo- 
gyrate, having leevo-rotation). Ripe hips (Rosas Caninos Fructus, 
B. P.) contains 30 per cent, of such sugar, besides gum and acid 
malates and citrates. Fruit-sugar, as gathered in the form of syrup 
by bees, is probably a mixture of these two varieties. It is gradu- 
ally altered to a crystalline or granular mass of grape-sugar^ as seen 
in dried fruits, such as raisins (Uvos, B. P.) and the prune (Prunum, 
U. S. P.), and in solidified honey [Mel, B. P., U. S. P.). This, the 
common form of grape-sugar, is dextrogyrate, and hence is sometimes 
termed dextrose, to distinguish it from laevulose. Diluted with twice 
its weight of water, it yields a liquid having the sp. gr. 1.101 to 
1.150. Honey often contains pollen, hairs, spores, the dust and dirt 
from the flowers, and various flocculent matters which cause it to 
ferment and yield mannite, alcohol, and acetic acid; hence for use 
in medicine it is directed (Mel Despumatum, U. S. P.) to be clarified 
by melting and straining while hot through flannel previously 
21 



470 ORGANIC CHEMISTRY. 

moistened with warm water. A mixture of clarified honey 80 per 
cent., acetic acid 10 per cent., and water 10 percent, is oflicial under 
the name of Oxymel (from o^vq, oxus, acid, and jjleXi, meli, honey). 
A similar mixture of honey with acetic acid containing the soluble 
portions of squill-bulbs (Scilla, B. P.) is known as Oxymel of Squill 
(Oxymel Scillce, B. P.). Honey and cane-sugar are the bases of 
the official Confections. 

Maltose, C 12 H 22 O u . — This crystallizable sugar is formed, together 
with dextrin, when diastase or dilute acids act upon starch. In the 
case of diastase it is the ultimate product, but the dilute acids may 
convert it into dextrose. It differs also from dextrose in its optical 
activity. 

Cane-sugar, maltose, and grape-sugar yield alcohol and carbonic 
acid gas by fermentation, the cane-sugar nearly always passing into 
grape-sugar before the production of alcohol commences. 

C 6 H 12 6 = 2C 2 H 5 HO + 2C0 2 

Grape-sugar. Alcohol. Carbonic acid gas. 

In bread-making some of the starch is converted into dextrin, and 
this into sugar by the ferment. The above action then goes on, the 
liberation of gas producing the rising or swelling of the mixture of 
flour, water, and yeast (dough), the temperature to which the mass 
is subjected in the oven causing escape of most of the alcohol and 
further expansion of the bubbles of carbonic acid gas in every part 
of the now spongy loaf. The carbonic acid gas gradually evolved 
when flour is worked up for bread with a mixture of dry sodium 
bicarbonate and tartaric acid (best preserved by previous admixture 
with dried flour and a little magnesium carbonate) — baking-powder — 
exerts similar influence. The least objectionable method of intro- 
ducing carbonic acid gas, however, is that of Dauglish, whose 
patent aerated bread is made from flour by admixture with carbonic 
acid water under pressure by the aid of machinery. On removal 
from the cylinder the resulting dough expands by the natural elas- 
ticity of the imprisoned carbonic acid gas, and the bake-oven com- 
pletes the process. The crumb of bread is official (Mica Pants, B. P.). 
All fermented bread retains, obviously, a little alcohol, sometimes 
0.25 per cent. 

Action of Alkali on Sugar.— To a little solution of grape- 
sugar add solution of potash or soda or solution of potassium 
carbonate, and warm the mixture ; the liquid is darkened in 
color from amber to brown according to the amount of sugar 
present. A trace of picric acid greatly intensifies the color. 

Tests. — The copper reaction, the fermentation process, and 
the effect of alkalies form three good tests of the presence of 
grape-sugar and, indirectly, of cane-sugar. A piece of merino 
or other woollen material, previously dipped in a solution of 
stannic chloride and dried, becomes of a brown or black color 
when dipped; in a solution of glucose and heated to about 
300° F. by holding before a fire. 



LACTOSES. 471 

Melitose or Melitriose (from eucalyptus) is a triose, giving on hy- 
drolysis galactose, dextrose, and fructose. Meletizose (from the 
larch), Trehalose (from Turkish manna), and Maltose (from starch), 
belong to the saccharoses. 

" Honey-dew" is a viscid saccharine matter occasionally met with 
on the leaves of the lime, maple, black alder, rose, and other trees, 
being a sweet principle exuded from aphides. Sometimes it is 
sufficiently abundant to dry and fall on the ground, forming a veri- 
table " shower of manna." It is a mixture of cane-sugar, inverted 
sugar, and dextrin. 

Barley-sugar is made by simply heating cane-sugar till it fuses, a 
change from the crystalline to the uncrystallizable condition occur- 
ring. Treacle (Theriaca, B. P.), Molasses or Melasses (from Mel, 
honey), or Golden Syrup chiefly results from the application of too 
much heat in evaporating the syrups of the sugar-cane ; it is a mix- 
ture of cane-sugar with uncrystallizable sugar and more or less 
coloring matter. Liquorice-root ( Glycyrrhizo3 Radix, B. P.) contains 
a considerable quantity of uncrystallizable sugar. 

Caramel. — Heat a grain or two of sugar in a test-tube until it 
blackens and froths ; the product is caramel or burnt sugar (the 
Saccharum TJstum of pharmacy). It is used as a coloring agent for 
gravies, confectioneries, spirits, vinegar, and similar materials. It 
is a mixture of caramels. 

Milk-sugar, or Lactose (C 12 H 22 ,O u H 2 0) (Saccharum Lactis, 
U. S. P.), the sweet principle of milk of animals, is not sus- 
ceptible of alcoholic or vinous fermentation by ordinary yeast ; 
certain varieties of the fungus, however, convert it into alco- 
hol. It resembles grape-sugar in reducing an alkaline solution 
of copper with precipitation of suboxide. It is obtained from 
milk by adding a few drops of acid, stirring, setting aside for 
the curds to separate, filtering, evaporating the whey to a small 
bulk, filtering again if necessary, and allowing to cool and crys- 
tallize. The deposited crude " s^ar-sand " is afterward refined 
and recrystallized. It usually occurs in trade " in cylindrical 
masses two inches in diameter, with a cord or stick in the axis, 
or in fragments of cakes — grayish-white, crystalline on the 
surface and in its texture, translucent, hard, scentless, faintly 
sweet, gritty when chewed." Thus obtained, milk-sugar has 
the formula above given, but if deposited during evaporation 
the crystals are anhydrous, C 12 H 22 O n . It is soluble in 6 parts 
of cold and 3 of boiling water ; slightly soluble in alcohol, 
insoluble in ether. Powdered milk-sugar is used in pharmacy 
as a vehicle for potent solid medicines. Milk-sugar is convert- 
ible, by the action of dilute acids, into galactose and dextrose ; 
these may be reunited to form milk-sugar. 

" If about 1 grm. of powdered sugar of milk be sprinkled upon 
about 5 cc. of cold sulphuric acid contained in a flat-bottomed 



472 ORGANIC CHEMISTRY. 

capsule, the acid may acquire a greenish or reddish, but no brown 
or brownish-black, color within half an hour (absence of cane-sugar)." 
— U.S. P. 

Saccharic Acid, H 2 C 6 H 8 8 or C 4 H 4 (OH),(COOH) 2 , is the 
result of oxidizing sucrose, dextrose, starch, gum, and lignin 
by nitric acid. Mucic Acid, isomeric with saccharic acid, may 
be obtained in the same way by acting on lactose, gum, and 
dulcite. 



QUESTIONS AND EXERCISES. 



Into what three classes may the carbohydrates be divided? — How is 
grape-sugar obtained from cane-sugar ? — How are cane-sugar and grape- 
sugar analytically distinguished ? — How is dextrose obtained from starch ? 
— Mention the chief sources of cane-sugar. — Give chemical explanations 
of the processes of bread -making. — What is the difference between fruit- 
sugar and honey ? — What is oxymel ? — Describe the effect of heat on 
cane-sugar. — How is milk-sugar obtained ? — How does it differ from other 
sugars ? — Whence are mucic and saccharic acids obtained ? 



Amyloses, or Amyloids, nC 6 H 10 O 5 . 

Starch (w-C 6 H 10 O 5 ) is contained in large or small quantities 
in nearly every plant. It forms about 60-70 per cent, of wheat 
and from 20 to 30 per cent, of potatoes. The starch officially 
recognized in the United States Pharmacopoeia (Amylwn) is 
that of maize (Zea Mays). 

Processes. — Rasp or grate or scrape with a knife a portion of 
a clean raw potato, letting the pulp fall on to a piece of muslin 
placed over a small dish or test-glass, and then pour a slow 
stream of water over the pulp ; minute particules or granules 
of starch pass through the muslin and sink to the bottom of 
the vessel, fibrous matter remaining on the sieve. This is 
potato starch. Even diseased potatoes furnish good starch by 
this method. Wheat starch may be obtained by tying up some 
flour in a piece of calico and kneading the bag in a slow stream 
of water flowing from a tap, the washings running into a deep 
vessel, at the bottom of which the white starch collects ; the 
sticky matter remaining in the bag is gluten. 

The blue starch of the shops is artificially colored with smalt or 
indigo to neutralize the yellow tint of recently washed linen ; it 
should not be used for medicinal purposes. Starch dried in mass 
splits up into curious columnar masses, resembling the basaltic 
pillars of Fingal's Cave in Staffa or those of the Giant's Causeway 
in the north of Ireland. The cause of the phenomenon, which may 
also be seen in grain tin, is not conclusively known. 



AMYLOSES. 473 

Gluten is the body which gives tenacity to dough and bread. It 
seems to be a mixture of vegetable fibrin, vegetable casein, and an 
albuminous matter termed glutin. These substances and gluten 
itself are closely allied ; each contains about 16 per cent, of nitrogen. 
Wheaten Flour {Farina Tritici, B. P.) contains about 72 per cent, of 
starch and ] 1 of gluten, as well as sugar, gum, fine bran, water, and 
ash. The compactness of barley, well seen in husked or pearl 
barley (Rordeum decorticatum, B. P.), is said to be due to the large 
amount of vegetable fibrin present. During germination the fibrin 
is destroyed; hence, probably, the cretaceous character of malt. 
Oatmeal (Avence Farina, U. S. P.), popular as " porridge," is rich 
in albumenoids or flesh-forming constituents, containing nearly 16 
per cent. Sago is granulated starch from the sago palm ; tapioca 
from the bitter cassava ; each has less than 1 per cent, of albumen- 
oids. The white translucent rice grains are the husked seeds of 
Oryza sativa. Rice ( Oryza) and its flour, or ground rice ( Oryzce 
Farina), are official in the Pharmacopoeia of India. Rice is a staple 
article of food in tropical countries. Ground rice resembles flour of 
wheat in composition, but contains from 85 to 90 per cent, of starch. 

Mucilage of Starch. — Mix two or three grains of starch with 
first a little and then more water, and heat to the boiling-point ; 
starch mucilage {Mucilago Amyli, B. P.) results. 1 part of 
starch to 200 of water gives " Starch Test-solution" U. S. P. 

This mucilage or paste is not a true solution ; by long boiling, 
however, a portion of the starch becomes dissolved. In the latter 
case the starch probably becomes somewhat altered. 

Chemical Test. — To some of the mucilage add a very little 
free iodine ; a deep-blue color is produced. 

This reaction is a very delicate test of the presence of either 
iodine or starch. The starch must be in the state of mucilage ; 
hence in testing for starch the substance supposed to contain it must 
be first boiled with water. The solutions used in the reaction 
should also be cold, or nearly so, as the blue color disappears on 
heating, though it is partially restored on cooling. The iodine re- 
agent may be iodine-water or tincture of iodine. In testing for 
iodine its occurrence in the free state must be ensured by the addi- 
tion of a drop, or even less, of chlorine-water. Excess of chlorine 
must be avoided, or iodine chloride will be formed, which does not 
color starch. 

The so-called starch iodide scarcely merits the name of a chem- 
ical compound, the state of union of its constituents being so feeble 
as to be decomposed at 100° F. Substances that attack free iodine 
remove that element from starch iodide. The alkalies, hydrosul- 
phuric acid, sulphurous acid, and other reducing agents, destroy the 
blue color. With nitric acid starch yields an explosive compound 
{Xyloidin), C 12 H 16 (NO 2 ) 4 O 10 or O u H 16 6 (N0 8 ) 4 . 

Composition of Starch-granules. — Starch-granules consist mainly 
of granulose, soluble in cold water and giving an indigo color with 



474 ORGANIC CHEMISTRY. 

iodine, and starch cellulose, insoluble in water, and giving with 
iodine a dirty yellow color, with, possibly, other carbohydrates. 
The starch cellulose forms an external coating upon the granule, and 
also exists, mixed with the granulose, inside the granule. If this 
coating be broken by mechanical means, the continued application of 
cold water will remove all the granulose, leaving the cellulose insolu- 
ble. By the action of diastase, ptyalin, and other ferments, and by 
other means, the granulose may be converted into sugar and dex- 
trin, leaving the starch cellulose unacted upon. 

Microscopical Examination of Starches. 

All kinds of starch afford the blue color with iodine, showing 
their chemical similarity. Physically, however, the granules of dif- 
ferent starches differ from each other ; hence a careful microscopical 
examination of any starch, or of any powder or vegetable tissue con- 
taining starch, enables the observer to state, with a high degree of 
probability, the source of the starch, either at once if he has much 
experience, or after comparing the granules in question with 
authentic specimens. A glance at the accompanying eight engrav- 
ings* (Figs. 42 to 49) of common starches will show to what extent 
different starch-granules naturally differ in size, shape, general 
appearance, distinctness and character of the rugae, and position of 
the more or less central point or hilum. While from different 
starches individual granules may be picked out which much resem- 
ble each other, the appearance of each starch as a whole is fairly 
characteristic ; that is to say, each group of granules differs in one 
or more characters from similar groups of granules of other starches. 

A quarter-inch object-glass will commonly suffice for the micro- 
scopical observation of starch. A very little of the starch is mixed 
on a glass slide with a drop of water, a piece of thin covering-glass 
placed on the drop and gently pressed, so as to provide a very thin 
layer for observation. Instead of water, diluted spirit of wine, 
diluted glycerin, turpentine or other essential oil, Canada balsam, 
and other fluids may be used in cases where the markings or other 
appearances are not well defined. The illumination also of the 
granules may be varied, the light being reflected or transmitted, con- 
centrated or diffused, white or colored, polarized or plain. Polarized 
light is especially valuable in developing differences and in intensi- 
fying the effects of obscure markings. By polarized light the gran- 
ules of potato starch appear as if traversed by a black cross ; wheat 
starch-granules and many others also peculiarly and characteris- 
tically influence polarized light. Distinctive characters will some- 
times present themselves only when the granules are made to roll 
over in the fluid in which they have been temporarily mounted or 
when the slide is gently warmed. Starches which have already been 
subjected to the influence of heat — partly, as in sago or tapioca, or 
almost entirely, as in bread — will of course differ in appearance from 

*By permission of Messrs. Longmans & Co. these engravings have 
been copied, with very few modifications, from the plates in two of the 
three volumes of the original edition of Pereira's Materia Medica, 



STARCH. 



475 



STARCHES 

(Magnified 250 diameters). 



Figs. 42 to 49. 




476 ORGANIC CHEMISTRY. 

granules of the same starch before being dried, cooked, or torrefied. 
The characters of a starch will also somewhat vary according to the 
age and condition of the plant yielding it. 

The description of the microscopical characters of the official 
varieties of starch is as follows: 1. Wheat starch : A mixture of 
large and small granules, which are lenticular in form, and marked 
with faint concentric striae surrounding a nearly central hilum. 
2. Maize starch : Granules more uniform in size, frequently polyg- 
onal, somewhat smaller than the large granules of wheat starch, 
and having a very distinct hilum, but without evident concentric 
striae. 3. Rice starch : Granules extremely minute, nearly uniform 
in size, polygonal, hilum small and without striae. 

(For plates and descriptions of the characters of other starches 
occurring in plants used for medicinal purposes the reader is referred 
to works on Materia Medica, and to the indexes of Journals of 
Pharmacy, as well as to general works and magazines on microscopy. 
For engravings of starch-granules in situ, vide Berg's "Anatomischer 
Atlas," published by Gaertner, Berlin.) 

The student may place fair confidence in the accompanying litho- 
graphs and in most of the published engravings of starch-granules ; 
but in microscopical analyses of importance the worker should, if 
possible, himself obtain actual specimens of starches for comparison 
from the respective seeds, fruits, and other tissues. 

Inulin, (C 6 H 10 O 5 ) 6 H 2 O (Kiliani), is associated with similar bodies, 
pseudo-inulin, (C 6 H 10 O 5 ) 16 H 2 O, and inulenin, (C 6 H 10 O 5 ) ]0 2H 2 O (Tan- 
ret). It is a white powder, apparently occupying the place of starch 
in the roots of many plants, especially those of the natural order 
Compositce. 20 to 45 per cent, has been obtained from elecampane 
{Inula helenium). It is also contained in the dahlia, colchicum, 
arnica, dandelion, chicory, artichoke, etc. It is soluble in boiling 
water, nearly all being redeposited on cooling. Iodine turns it yel- 
low. Long ebullition converts it into a kind of gum. Like starch, 
inulin is convertible into sugar, but by its own special ferment, the 
existence of which, in the Jerusalem artichoke, has been demon- 
strated by Professor J. R. Green. This ferment differs from diastase 
in being without the power of converting starch into sugar. 

Lichenin (wC 6 H 10 O 5 ) is a white starch-like powder largely con- 
tained in many lichens — Iceland "moss," Cetraria Islandica, and 
many others. It is soluble in boiling water, and the fluid gelatinizes 
on cooling. It may be precipitated from its aqueous solution by 
alcohol. With iodine it gives a reddish-blue color. 

Glycogen, or animal starch, is the name given to the solid matter 
stored in the liver and resulting from the dehydration of the digested 
hydrated food which has been carried to the liver by the portal vein. 

Dextrin (?iC 6 H 10 O 5 ). — Mix a grain or two of starch with half 
a test-tubeful of cold water and a drop or two of sulphuric 
acid, and boil the mixture for a few minutes ; no mucilage is 
formed, and the liquid, if sufficiently boiled, yields no blue 
color with iodine ; the starch has become converted into dex- 
trin and some sugar. Dextrin is also produced if starch is 



STARCH. 477 

maintained at a temperature of about 320° F. for a short time. 
Dextrin is now largely manufactured in the latter way, and a 
paste of it is used by calico-printers as a vehicle for, colors ; it 
is termed British gum. The change may also be effected by 
diastase, a peculiar ferment existing in malt. Mix two equal 
quantities of starch with equal amounts of water, adding to 
one a little ground malt, then heat both slowly to the boiling- 
point : the mixture without malt thickens to a paste or pud- 
ding ; that with malt remains thin, its starch having become 
converted into dextrin and a sugar termed maltose. 

Diastase is probably a mixture, but possibly an oxidation-product, 
of the coagulable albumenoids. It is so named from dtdaraaig (dias- 
tasis), separation, in allusion to the separation, or rather alteration, 
it effects among the constituent atoms of the molecule of starch. 
This function is shared by the saliva, pancreatic juice, bile, and the 
intestinal and other juices. The function is completely destroyed 
when the albumenoids are coagulated by a temperature of from 176° 
to 178° F. 

The Action of Diastase upon Starch. — Diastase has scarcely any 
action upon unbroken starch-granules. The granules must be rup- 
tured by gelatinization with heat and moisture or in some other way. 
When a solution containing diastase, such as a cold-water infusion 
of malt, is allowed to act upon gelatinous starch or starch-paste at 
140° to 160° F., liquefaction occurs. It is possible to operate so that 
when liquefaction has taken place the solution shall give no reaction 
for sugar or dextrin. If this solution be concentrated and allowed 
to cool, a glistening white precipitate of soluble starch falls. Soluble 
starch is probably the result of the partial decomposition of the 
more complex molecule of granulose or gelatinous starch. The next 
step in the action of diastase upon gelatinous starch is the breaking 
down of the soluble starch-molecule into dextrin and a sugar called 
maltose. At least ten dextrins are successively produced, each 
simpler than the one preceding it, the proportion of maltose being 
correspondingly increased. The dextrins first produced give a red 
or brown color with iodine, while those last produced, and having a 
simpler molecule, give no color with iodine. The final reaction may 
be expressed thus : 

10(C 12 H 20 O 10 ) + 8H 2 = 8(C 12 H 22 O n ) + 4(C 6 H 10 O 5 ) 

Soluble starch. Maltose. Dextrin. 

The dextrins are distinguished by their rotatory power, their redu- 
cing action on cupric salts, and in other ways. 

Starch heated with glycerin is converted into the soluble variety. 
The latter may be precipitated from an aqueous solution by strong 
alcohol. A strong solution in water gradually gelatinizes, owing to 
reconversion into insoluble starch (Zulkowsky). 

The Action of Dilute Acids upon Starch. — Dilute acids act upon 
gelatinous starch in the same way as diastase, except that the final 
product is glucose. 
21* 



478 ORGANIC CHEMISTRY. 

Malt (the word malt is said to be derived from the Welsh mall, 
soft or " rotten") is simply barley which has been softened by 
steeping in water, allowed to germinate slightly, and further change 
then arrested by the application of heat in a kiln. During germ- 
ination the gluten breaks up and yields a glutinous substance termed 
vegetable gelatin, diastase, and other matters. To the vegetable gel- 
atin is due much of the " body " of well-malted and slightly hopped 
beer 5 it is precipitated by tannic acid 5 hence the thinness of ale 
(pale or bitter) brewed with a large proportion of hop or other 
materials containing tannic acid. A portion of the diastase, react- 
ing on the starch of the barley, converts it into dextrin, and, indeed, 
carries conversion to the further stage of maltose, as will be ex- 
plained immediately. The temperature to which the malt is heated 
is made to vary, so that the sugar of the malt may or may not be 
partially altered to a dark-brown coloring material : if the temper- 
ature is high, the malt is said to be high-dried and is used in porter- 
brewing 5 if low, the product is of lighter color and is used for ale. 
The diastase remaining in malt is still capable of converting a large 
quantity of starch into dextrin and sugar (maltose) ; hence the 
makers or distillers of the various spirits operate on a mixture of 
malted and unmalted grain in preparing liquors for fermentation. 

Extract of Malt is an evaporated infusion of malt. Taken with 
food, its diastase aids in the conversion of starch into a variety of 
sugar termed maltose, and dextrin, and, pro tanto, assists enfeebled 
digestive powers. 

3C 6 H 5 + H 2 = C 12 H 22 O n + C 6 H 10 O 5 

Starch. Maltose. Dextrin. 

As diastase begins to lose its power at temperatures above 150° F., 
that degree should not be exceeded in evaporating the infusion ; 
indeed, if the dissolved albumenoid matters are to be retained, the 
evaporation should be conducted at 120° F. 

The following method serves for the estimation of the dia- 
stasic power of malt extract: 1.5 gram of the extract is dis- 
solved in 15 cc. of water and mixed with a mucilage of .1 gram 
of starch in 100 cc. of water. The mixture is raised to 140° 
F. in temperature, and tested from time to time by adding two 
drops of iodine solution to 5 cc. of it, and comparing with 5 cc. 
of a similar mixture to which no starch has been added. No 
difference of tint between the two solutions indicates comple- 
tion of the reaction. Grood malt extract will accomplish this 
within half an hour ; some samples will take less time, but 
many commercial extracts will require three hours or more. 

Gum isa frequent constituent of vegetable juices, existing in large 
quantity in several species of Acacia. The nature of gums is very 
little known, though most probably they all belong to the carbo- 
hydrates. According to Fremy, gum is a calcium salt, sometimes 
partially a potassium salt, of the gummic or arable radical, though 
consisting mostly of arabin or arabic acid alone. The formula of 



CELLULIN. 479 

gummic acid is said to be H 2 C 12 H ]8 O 10 ,H 2 O, but, from the important 
researches of 0' Sullivan, it would seem to be far more complex, a 
multiple of the empirical formula, C 6 H 10 O 5 — Raoult (C 5 H 10 O 5 ) 7 . 
Gum differs from dextrin in yielding mucic acid when oxidized 
by nitric acid. Good adhesive mucilages may be made from such 
gum-arabic substitutes as " ghatti," " amrad," etc. Cerasin, or 
cherry-tree gum, 4 is a calcium metagummate, an insoluble modi- 
fication of acacia gum. Bassorin, traganthin, or adraganthin, 
(C 12 H 20 O 10 ) is a form of gum which is insoluble in water, but 
absorbs large quantities of that liquid and forms a gelatinoid mass : 
it occurs largely in tragacanth, combined, like arabin, with cal- 
cium. Pectin, or vegetable jelly (C 32 H 40 O 28 ,4H 2 O), is the body 
which gives to expressed vegetable juices the property of gelatin- 
izing: it forms the chief portion of Irish or carrageen "moss" 
(Chondrus crispus). Ceylon "moss" (Gracillaria lichenoides and 
G. confervoides, P. I.) contains from one-third to three-fourths of 
vegetable jelly. 

The mucilage of marshmallow-root (Althea officinalis) and of 
linseed or common flaxseed (Linum usitatissimum) is a gum-like 
substance containing much mineral matter. It is the basis of the 
infusions termed mallow tea and linseed tea. Somewhat similar 
mucilage occurs in infusion of bael : it is also largely yielded by 
the seeds of the quince (Pyrus Cydonia), as well as by the bark of 
the red or slippery elm (Ulmus, IT. S. P.), Salep, the powdered 
dried tubers of many species of Orchis, contains a large quantity 
of such matter. Squill also. The Indian Okra (Hibisci Capsidce, 
P. I., from Hibiscus esculentus) and Ispaghul or Spogel seed {Ispa- 
ghulce Semina, P. I., from Plantago ispaghula) also appear to con- 
tain a considerable quantity. In Sassafras-pith (Sassafras Medidlos, 
U. S. P.) starch and mucilage occur. 

Cellulin, or Cellulose, C 6 H 10 O 5 , the woody fibre of plants, familiar, 
in the nearly pure state, under the forms of "cotton-wool" (Gos- 
sypium Purifcatum, U. S. P., hairs of the seed of various species 
of Gossypium), paper, linen, and pith, is another substance isomeric, 
probably polymeric, with starch. Lignin is a closely-allied body 
lining the interior of woody cells and vessels. By the action of 
nitric acid of various strengths on cellulin, mono-, di-, or tri-nitro- 
cellulins are readily formed: C 6 H 9 4 N0 3 , C 6 H 8 3 (N0 3 ) 2 , C 6 H ? 2 ,- 
(N0 3 ) 3 . Trinitrocellulin is highly-explosive gun-cotton ; dinitro- 
cellulin is not sufficiently explosive for use instead of gunpowder ; 
mononitrocellulin is scarcely at all explosive. The heat of a water- 
bath may explode trinitrocellulin, but not dinitrocellulin if pure. 
The three displaceable atoms of hydroxyl in cellulin may be dis- 
placed by bodies other than the nitric radical. 

Dinitrocellulin (Pyroxylinum, U. S. P.). — Mix 22 parts of sulphuric 
acid and 14 of nitric in an earthenware mortar. When cooled to 
about 32° C. (90° F.), immerse 1 part of cotton-wool in the mixture, 
and stir it with a glass rod, so that it is thoroughly and uniformly 
wetted by the acids. Macerate until a sample, washed with water 
and then with alcohol, is soluble in a mixture of one volume of 
alcohol and three of stronger ether. Transfer the cotton to a vessel 



480 ORGANIC CHEMISTRY. 

containing a considerable volume of water, stir it rapidly and well 
with a glass rod, decant the liquid, pour more water upon the mass, 
agitate again, and repeat the affusion, agitation, and decantation 
until the washing ceases to give a precipitate with barium chloride 
or to taste acid. Drain the product on filtering-paper and dry on a 
water-bath. 

Pyroxylin may also be made by soaking 7 parts of white filtering- 
paper, which has been washed in hydrochloric acid and dried, in a 
mixture of 140 parts of sulphuric acid (sp. gr. 1.82) and 70 of nitric 
acid (1.37) for three hours, and well washing the product (Guichard). 

Mononitrocellulin and trinitrocellulin are insoluble in a mixture 
of alcohol and ether ; dinitrocellulin, or pyroxylin, is soluble, the 
solution forming ordinary collodion {Collodium, U. S. P.). The 
official proportions are 3 grm. of pyroxylin dissolved in a mixture 
of 75 cc. of ether and 25 of alcohol. After digesting for a few 
days, decant the liquid from any sediment and preserve it in a well- 
corked bottle. It dries rapidly upon exposure to the air, and leaves a 
thin, transparent film, insoluble in water or spirit. Flexible Collo- 
dion {Collodium Flexile, U. S. P.) is a mixture of collodion (92 
parts), Canada balsam (5 parts), and castor oil (3 parts). Blistering 
Collodion {Collodium Vesicans, B. P.), Collodium Cantharidatum, 
U. S. P., or Cantharidal Collodion, is a solution of pyroxylin con- 
taining the active blistering principle of cantharides. A Styptic 
Collodion {Collodium Stypticum, U. S. P.), containing tannic acid, 
is also official. Many articles of utility and beauty are now made 
of pyroxylin variously colored and sold under the name of xylonite 
{^vlov, xulon, wood) or celluloid (cellulin-like). 

Tunicin, or animal cellulose, exists. It is extracted from ascidians 
and cynthians. 

Isomerism. — Allotrophy. — Polymorphism. 

The composition of dextrin is represented by the same formula 
as that of starch — namely, C 6 H 10 O 5 ; for it has the same percentage 
composition as starch. Inulin (p. 476) and cellulose (p. 479) have 
also a similar formula. There are many other bodies similar in 
centesimal composition, but dissimilar in properties ; such substances 
are termed isomeric (from Icog, isos, equal, and /uepog, meros, part) ; 
and their condition is spoken of as one of isomerism. There is 
sometimes good reason for doubling or otherwise multiplying the 
formula of one of two isomers, isomerides, or isomeric bodies. Thus 
a molecule of ethylene (olefiant gas), the chief illuminating constit- 
uent of coal-gas, is represented by the formula C 2 H 4 , while a mole- 
cule of amylene, an anaesthetic liquid hydrocarbon, obtained from 
amy lie alcohol, though having the same percentage composition as 
olefiant gas, is represented by the formula C 5 H 10 5 for amylene, 
when gaseous, is about twice and a half as heavy as ethylene, and 
must contain, therefore, in each molecule, twice and a half as many 
atoms, for (Avogadro) these equal volumes must contain equal 
numbers of molecules ; its formula is, consequently, constructed to 
represent these proportions. (Read again pages 36 to 60.) This 
variety of isomerism is termed polymerism (from Kokvq, polus, many 



ISOMERISM. ALLOTROPHY. 481 

or much, and pepog, part). Formic aldehyde, CH 2 0, acetic acid, 
2 H 4 2 , and lactic acid, C 3 H 6 3 , are, obviously, polymers. Meta- 
stannic acid (vide p. 243) is a polymeric variety, or polymeride, of 
stannic acid. An illustration of a second variety of isomerism is 
seen in the case of ammonium cyanate and urea, bodies already 
alluded to in connection with cyanic acid. These and several other 
pairs of chemical substances have dissimilar properties, yet are 
similar in elementary composition and in the centesimal proportion 
of the elements, and we cannot escape the conclusion that each 
molecule possesses the same number of atoms. But the reactions 
of these bodies indicate the probable nature of their construction ; 
and this is shown in their formulas by the disposition of the symbols. 
Thus ammonium cyanate is represented by the formula NH 4 CNO, 
urea by CO(NH 2 ) 2 . Such bodies are termed metameric (from //era, 
meta, a preposition denoting change, and /nipoc;), and their condition 
spoken of as one of metamerism. (For two metameric nitro-methylic 
and also two nitro-ethylic bodies see p. 405.) Ethyl acetate (p. 406) 
is metameric with butyric acid (p. 488), for they have the same per- 
centage composition and their vapors have the same specific gravity, 
and each therefore might be represented by the formula C 4 H 8 2 ; 
but their properties warrant us in assuming that their atoms 
occupy different positions in the two molecules — justify us in 
giving CH 3 COOC 2 H 5 as a picture of a molecule of ethyl acetate, 
and CgH-COOH as a picture of a molecule of butyric acid. Methyl 
acetate (CH 3 COOCH 3 ), propionic acid (C 2 H 5 COOH)* and ethyl 
formate (H*CO , OC 2 H 5 ) are isomers of the metameric variety, or 
metamers or metamerides ; also quinine and quinidine, cinchonine 
and cinchonidine, and many of the volatile oils, etc. The isomer- 
ism of starch and dextrin may be of a polymeric or of a metameric 
character ; but we do not yet know which, and must therefore at 
present give them identical formulae, though it is most probable that 
many of the carbohydrates are multiples of the mere empirical 
formulas, since dextrin (xC 6 H 10 O 5 ) by hydration produces maltose, 
C^H^Ojj, which would point to the formula of dextrin as being at 
least (C 6 H 10 O 5 ) 2 , while the extent to which it lowers the freezing- 
point of a solvent points to (C 6 H 10 O 5 ) r Patient accumulation of 
facts and the aid of the theory of valency will, doubtless, sooner or 
later, fully explain all cases of isomerism. 

Substances similar in composition and constitution, yet differing 
in properties, are termed allotropic (allog , alios, another, rpd-n-oc, tropos, 
condition). Thus ordinary phosphorus, kept at a temperature of 
about 450° F. in an atmosphere from which air is excluded, becomes 
red, opaque, insoluble in liquids in which ordinary phosphorus is 
soluble, oxidizes extremely slowly, and only ignites when heated to 
near 500° F. (red or amorphous phosphorus). A black allotropic 
variety of phosphorus is known. There are also three allotropes of 
carbon which are respectively crystalline, graphitic, and amorphous. 
Sulphur may be obtained in the viscous as well as in the hard, brit- 

* For explanation of formulae see section on Aldehydes and Acids, 
p. 482. 



482 ORGANIC CHEMISTRY. 

tie condition. Another illustration of allotropy is seen in the vari- 
eties of tartaric acid which have different optical properties, but 
otherwise are identical ; they are in neither of the above-mentioned 
states of isomerism, but are allotropic modifications of the same 
substance. The constitution of such bodies is perhaps best con- 
ceived by the aid of stereochemical hypotheses. Occasionally one 
and the same substance crystallizes in two distinct forms ; its state 
is then described as one of polymorphism (nolvc^polus, many ; [lop^i/, 
morphe, form). Sulphur is polymorphous. It crystallizes by slow 
cooling in (1) prismatic crystals of sp. gr. 1.98, while in nature it 
occurs in (2) octahedra of sp. gr. 2.07. Melted and poured into 
water, sulphur takes up (3) the form of caoutchouc of sp. gr. 1.96. 
These differences warrant the statement that sulphur occurs in three 
distinct allotropic conditions. Possibly such conditions result from 
the association of different numbers of atoms in the molecule of the 
element ; that is, allotropic bodies may simply be physically poly- 
meric^ or in some other way be mere physical isomerides. 



QUESTIONS AND EXERCISES. 

How is wheat starch or potato starch isolated? — Define gluten and 
glutin. — Enumerate the proximate principles of wheaten flour. — Is starch 
soluble in water? — Which is the best chemical test for starch? — Distin- 
guish physically between the varieties of starch. — Into what compound 
is starch converted by heat ? — What occurs when a mixture of starch and 
water is allowed to flow into hot diluted sulphuric acid? — If two equal 
amounts of starch with water be heated, one containing a small quantity 
of ground malt, what effects ensue? — Write a short article on the chem- 
istry of malting. — What is the nature of gum arabic? and how is it dis- 
tinguished from " British gum "? — Mention the properties of the products 
of the action of nitric acid of various strengths on cellulin. — How is 
pyroxylin prepared? — Explain isomerism, giving several illustrations. — 
Give examples of polymeric bodies. — State the formula of a body met- 
americ with urea. — Define allotropy and polymorphism, giving illustra- 
tions. 

ALDEHYDES AND ACIDS. 

General Formation. — The aldehydes and acids may be artificially 
formed by oxidation of the primary alcohols, glycols, etc. Monhy- 
dric alcohols, having only one hydroxyl (OH) group, form monobasic 
acids ; dihydric alcohols (glycols) having two hydroxyl groups, yield 
monobasic and dibasic acids ; and so on. Thus : 

CH 3 CH 2 OH} ieldg f CH 3 COH } and fCH 3 COC^ 

Ethyl alcohol J J iemS) { Acetic aldehyde j d,uu ( Acetic acid. 

yields CH 2 OH S C CH 2 OH 

COH ( and ) COOH 

Glycollic aldehyde, J (^ Glycollic acid. 

H 2 OH \and COH >> r COOH 

ethylene glycol J [ ^ 0H V an ^ J COOH 

Oxalic aldehyde, I I Oxalic acid. 



ALDEHYDES AND ACIDS. 483 

It will be seen that the groups COH and COOH denote respectively an 
aldehyde and an acid, the H in the COOH group being replaceable 
by a metal, such as CH 3 COONa (sodium acetate). (See also pp. 
409 and 456.) 

Acids may also be obtained by acting on the nitrites or cyanides 
of the hydrocarbon radicals with hydrochloric acid and water. Thus : 

CH 4 + Cl 2 = CH 3 C1 + HC1 

Methane. Chlorine. Monochloro- Hydrochloric 

methane. acid. 

CH3CI + KCN = CH 3 CN + KC1 

Monochloro- Potassium Methyl cyanide, Potassium 

methane. cyanide. or acetonitrile. chloride. 

CH 3 CN + 2H 2 + HC1 = CH3COOH + NH 4 C1 

Acetonitrile.* Water. Hydrochloric Acetic acid. Ammonium 

acid. chloride. 

Many aldehydes and acids occur in nature ; for example, oil of 
meadow-sweet (salicylic aldehyde), oil of bitter almonds (benzoic 
aldehyde), citric acid in lemons. 

General Reactions. — Aldehydes all form crystalline compounds 
with acid potassium sulphite, by oxidation they yield an acid, and 
by the action of nascent hydrogen they yield an alcohol, while acids, 
by nascent hydrogen, yield an aldehyde, and then an alcohol. With 
oxides, hydrates, carbonates, and sometimes with metals, acids form 
metallic derivatives. With the alcohols, acids yield alkylf or 
ethereal salts, as,- for instance, acetic ether. By the action of phos- 
phorus, chloride, iodide, or bromide their hydroxyl group is replaced 
by chlorine, iodine, or bromine : 

3CH3COOH 4- PCI3 = 3CH 3 C0-C1 4- PO3H3 
Acetic acid. Phosphorus Acetyl chloride. Phosphorous 

trichloride. acid. 

Like inorganic acids, they form anhydrides by the elimination of 
water : 

2CH3COOH - H 2 = ci'co} 
Acetic acid. Water. Acetic anhydride. 

The important aldehydes and acids will now be mentioned. 

-The reactions of nitrites indicate that the radical present is united to 
the carbon of the cyanogen, while the reactions of isonitriles (or cala- 
mines) indicate that the radical is united to the nitrogen. Hence such 
formula as CH3CN" and CH3NC. 

. f Alkyl Salts. Allcyl, from the Arabic article al, the, as in alkali, alco- 
nol, etc., and the termination common to the names of such radicals as 
ethyl, amyl, and phenyl, and as seen in methyl, the prototype of such 
names. (See p. 437.) In Germany the word ester, a mere variation of 
the word ether, is similarly employed. In the scientific chemistry of 
both countries ft is thus sought to restrict the name ethers to the oxides 
of radicals, as common ether, (CjHs^O (Miher, U. S. P.). 



484 ORGANIC CHEMISTRY. 

The Acetic Series. 

Acids of the Acetic Series, CnH 2n +iCOOH (monobasic), formed 
by the two general methods given — namely, from primary alcohols 
of the ethylic series and from cyanides of the paraffin hydrocarbon 

Formic Acid, HCOOH. Formic aldehyde, HCOH. (See p. 339.) 
Acetic Acid, CH 3 COOH (Methylformic acid). Obtained by the 
oxidation of alcohol and in other ways. (See p. 297.) 
Aldehyde, or Acetic Aldehyde, C 2 H 4 or CH 3 COH. 

Preparation. — Place together in a capacious test-tube or flask 
about 4 parts of spirit of wine, 6 of black manganese oxide, 
6 of sulphuric acid, and 4 of water, and gently warm the mix- 
ture ; aldehyde (alcohol c?e%drogenatum), a highly volatile 
liquid, is immediately formed, and its vapor evolved, recognized 
by its peculiar somewhat fragrant odor. Adapt a cork and 
rather long bent tube to the test-tube, and let some of the 
aldehyde slowly distil over into another test-tube, the condens- 
ing-tube being kept as cool as possible. Set the distillate 
aside for a day or two ; the aldehyde will have nearly all dis- 
appeared and acetic acid be found in the tube. Test the 
exposed liquid by litmus-paper ; it will be found to have an 
acid reaction : make it slightly alkaline by a drop or two of 
solution of sodium carbonate, then boil to remove any alcohol 
and aldehyde present, add sulphuric acid, and notice the cha- 
racteristic odor of the acetic acid evolved. 

These experiments will enable the process of acetification described 
in connection with acetic acid to be more fully understood. Pure 
diluted alcohol is not oxidized by exposure to air alone ; but in pres- 
ence of a ferment, bacterium aceti, it is oxidized first to aldehyde 
and then to acetic acid. 

In the above process the black manganese oxide and sulphuric 
acid furnish nascent oxygen : 



Mn0 2 + H 2 S0 4 


= MnS0 4 


+ + H 2 


Black manga- Sulphuric 


Manganese 


Oxygen Water. 


nese oxide. acid. 


sulphate. 


(atom). 



The nascent oxygen then acts on the alcohol, just as the oxygen 
of the air acts on the alcohol in fermented infusion of malt, beer, 
or wine, giving aldehyde : 

CH 3 CH 2 OH + = CH 3 COH -f H 2 

Alcohol. Oxygen Aldehyde. Water, 

(atom). 

The aldehyde rapidly, even when pure (more rapidly when impure), 
absorbs oxygen and yields acetic acid : 

2CH.COH 4- 2 = 2CH3COOH 

Aldehyde. Oxygen. Acetic acid. 



CHLORAL. 485 

Tests. — Aldehyde heated with solution of potash gives a 
brownish-yellow resinous mass of peculiar odor. Its aqueous 
solution reduces salts of silver, giving a mirror-like coating to 
the cleaned sides of a test-tube. When acted on by phenol 
dissolved in sulphuric acid, it gives a red color. Aldehyde on 
keeping or in contact with sulphuric acid, zinc chloride, etc. 
yields two polymerides — metaldehyde (xC 2 H 4 0) and paralde- 
hyde, C 6 H ]2 3 , the latter having a characteristic odor. The 
official paraldehyde {Paraldeliydum, U. S. P.) boils at 123°-125° 
C, dissolves in water, spirit, or ether, is neutral, and if it con- 
tains no ordinary aldehyde will not be colored on standing for 
two hours with solution of potash or soda. Add a little 
silver ammonium nitrate to a strong solution of paraldehyde, 
and on warming and allowing to stand a silver mirror will be 
formed. A mixture of 8 cc. of paraldehyde and an equal 
amount of alcohol, with 1 drop of phenolphtalein, should 
acquire a pink color, with, at the most, 0.5 cc. of normal potas- 
sium hydrate (limit of free acid). 

CHLORAL. 

Chloral, or Trichlor aldehyde, CCl 3 COH, is a chlorine substitution- 
derivative of aldehyde, though it cannot directly be obtained by 
acting on aldehyde by chlorine, because condensation-products are 
formed. 

Process. — Pass a rapid stream of dry chlorine into pure 
absolute alcohol so long as absorption occurs. During the first 
hour or two the alcohol must be kept cool, afterward gradually 
warmed till ultimately the boiling-point is reached. The prep- 
aration of a considerable quantity occupies several days. The 
crude product is mixed with three times its volume of sul- 
phuric acid and distilled, again mixed with a similar quantity 
of sulphuric acid and again distilled, and finally rectified from 
quicklime. 

The formation of chloral would at first sight seem to be due to 
the production from the alcohol (CH 3 CH 2 OH) of aldehyde (CH 3 - 
COH), through the removal of hydrogen by the chlorine, and the 
substitution of chlorine for hydrogen in the aldehyde (CH 3 COH), 
with formation of chlor-aldehyde or chloral (CCl 3 COH). But the 
reactions are far more complicated, being as follows : 

Aldehyde and hydrochloric acid are first formed : 

CH 3 CH 2 OH + Cl 2 = CH 3 COH + 2HC1 

Alcohol. Chlorine. Aldehyde. Hydrochloric acid. 

The nascent aldehyde unites with alcohol, forming acetal : 

CH 3 COH + 2C 2 H 5 OH = CH 3 'CH(OC 2 H 5 ) 2 + OH 2 
Aldehyde. Alcohol. Acetal. Water. 



486 ORGANIC CHEMISTRY. 

Acetal * by further chlorination yields trichloracetal : 

CH 3 -CH(OC 2 H 5 ) 2 + 3C1 2 = CC1 ? CH-(0C 2 H 5 ) 2 + 3HC1 

Acetal. Chlorine. Trichloracetal. Hydrochloric acid. 

Trichloracetal, when acted on by hydrochloric acid, yields ethyl 
chloride and chloral alcoholate : 

CC1 3 CH<^H5 + HC1 = CC1 3 CH<^H 5 + q^ 

Trichloracetal. Chloral alcoholate. Ethyl chloride. 

From the alcoholate chloral is liberated by treatment with sulphuric 
acid. 

CCl 3 -CH(OC 2 H 5 )OH + H 2 S0 4 = CCl 3 COH + C 2 H 5 HS0 4 + OH 2 

Chloral alcoholate. Sulphuric Chloral. Ethyl-hydrogen Water, 

acid. sulphate. 

Properties. — It is a colorless liquid, of oily consistence. Sp. gr. 
1.502. Boiling-point, 201.2° F. Its vapor has a penetrating smell 
and is somewhat irritating to the eyes. Mixed with water, heat is 
disengaged, and solid white, crystallizable chloral hydrate, CC1 3 CH- 
(OH) 2 , or Hydrate of Chloral {Chloral Hydras, B. P.), results. 
" Chloral hydrate," termed in the United States Pharmacopoeia 
" Chloral," with " Chloral Hydrate " as a synonym, is a true glycol, 
the water not being simply water of crystallization, but of combina- 
tion, the systematic name being trichlorethylidene glycol : 

C 2 H 4 (OH) 2 CCl 3 CH(OH) 2 

Ethylene glycol. Trichlorethylidene glycol. 

Chloral hydrate fuses when heated, solidifies at about 120° F. ; boils 
at from 202° to 206° F. It sublimes as a white crystalline powder. 
Both chloral and chloral hydrate are soluble in water, alcohol, ether, 
and oils. Oils and fats are also soluble in chloral hydrate. The 
aqueous solution should be neutral and give no reaction with silver 
nitrate. Chloral, especially if it contains a trace of acid, may 
undergo a spontaneous change into an opaque white isomeric modi- 
fication, metachloral, insoluble in water, alcohol, or ether, but con- 
vertible by prolonged contact with water or by distillation into the 
ordinary condition. By action of weak alkalies chloral yields for- 
mate of the alkali-metal and chloroform : 

CCljCOH + KOH = H-CO-OK + CHC1 3 . 

Chloral, or rather strong aqueous solution of chloral hydrate 
(3 in 4), injected beneath the skin yields chloroform and produces 
narcotic effects (Liebreich, Personne). Chloroform itself admits of 
similar hypodermic use (Richardson). If administered by the stom- 
ach, 30 to 80 grains of solid hydrate are required. The final prod- 
ucts of the reaction of the chloroform and blood are sodium formate 
and chloride. A strong spirituous solution of potash effects the 
same transformation : CHC1 3 + 4KOH = HCOOK + 3KC1 + 2H 2 0. 

* Methylal, CH2(OCH3)2, the lowest term of the series, is occasionally 
used as a soporific. 



CHLORAL HYDRATE. 487 

Solution of ammonia and moist calcium hydrate, as well as weak 
solutions of fixed alkalies, convert chloral hydrate into formate of 
the metal and chloroform. The reaction with the slaked lime being 
especially definite and complete (Wood), it may be employed in 
ascertaining the richness of a sample of commercial chloral hydrate 
in chemically pure chloral hydrate. 

2(CC1 3 CH(0H) 2 ) + Ca20H = 2CHC1 3 + (HCOO) 2 Ca + 2H 2 0. 
331 239 

From the foregoing equation and molecular weights it is 
obvious that 100 grains of chloral hydrate, if quite dry, will 
yield by distillation, with 30 grains of slaked lime and an 
ounce of distilled water (in a small flask and a long bent tube 
kept cool by moistened paper), 72.2 grains of chloroform by 
weight or (the sp. gr. of chloroform being taken at 1.497) 47.56 
grains by measure, or about 52 minims. 100 grains of the 
official chloral hydrate " should yield not less than 70 grains of 
chloroform." (Any such definite quantity of chloroform, on 
account of its volatile nature, is perhaps best measured, the 
weight being obtained by multiplying the volume by 1.5.) 

Small quantities of chloral hydrate in dilute solutions may be 
estimated by converting its chlorine into hydrochloric acid by nas- 
cent hydrogen, and titrating with volumetric solution of silver 
nitrate (Short). A quantity of solution containing not more than 
.05 of a gram is placed in a small flask with granulated zinc and 
acetic acid, and allowed to stand twenty-four hours : the solution is 
then poured off and the zinc washed two or three times with distilled 
water ; a little yellow potassium chromate is added, and it is then 
titrated with decinormal silver nitrate solution in the usual way, the 
acetic acid and zinc acetate not interfering with the indications. 
1000 cc. of the silver solution indicate 5.52, nearly, of chloral 
hydrate. 

Pure Chloral Hydrate. — Liebreich, who first proposed the use of 
chloral hydrate, gives the following as the characteristics of a pure 
article : Colorless, transparent crystals. Does not decompose by the 
action of the atmosphere, does not leave oily spots when pressed 
between blotting-paper, affects neither cork nor paper. Smells 
agreeably aromatic, but a little pungent when heated. Tastes bitter, 
astringent, slightly caustic. Seems to melt on rubbing between the 
fingers. Dissolves in water like candy, without first forming oily 
drops, and the solution is neutral or faintly acid to test-paper. Dis- 
solves in carbon bisulphide, petroleum, ether, water, alcohol, oil of 
turpentine, etc. Its solution in chloroform gives no color when 
shaken with sulphuric acid. Boiling-point, 203° to 205° F. It vol- 
atilizes without residue. Distilled with sulphuric acid, the chloral 
should pass over at 205° to 207° F. Melting-point, 133° to 136° F., 
again solidifying at about 120°. Gives no chlorine reaction on treat- 



488 



ORGANIC CHEMISTRY. 



ing the solution in water (acidulated by nitric acid) with silver 
nitrate. 

Impure Chloral Hydrate. — Yellowish, cloudy. Decomposes ; leaves 
spots by pressing between blotting-paper ; decomposes corks and 
paper of the packing. Smells pungent and irritating ; on opening 
the bottle is sticky and often emits fumes. Taste strongly caustic. 
With water forms oily drops or is partially insoluble. Boils at a 
higher temperature. On treating it with sulphuric acid turns 
brown, with formation of hydrochloric acid. Gives chlorine reac- 
tion on treating the solution in water (acidulated by nitric acid) 
with silver nitrate. 

Alcoholates of chloral are obtained on combining alcohols with 
chloral. Chloral alcoholate or trichlorethylidene ethyl ether, 

OIT 
CC1 3 CH <Cqp tt is obtained by mixing alcohol with chloral ; it is in 

fact " chloral hydrate " with one hydroxy 1 group replaced by 
(OC 2 H 5 ). 

Bromal, CBr 3 COH, Bromal Hydrate, CBr 3 CH(OH) 2 , and Bromal 
Alcoholates are produced when bromine instead of chlorine attacks 
alcohol. Iodal, CI 3 COH, also exists. 

Butyl Chloral, C 3 H 4 C1 3 C0H, originally, but erroneously, termed 
croton chloral, is a product of the action of dry chlorine on cold 
aldehyde. Its name expresses its constitution ; it is chlorinated 
butyric aldehyde, ordinary chloral being chlorinated acet-aldehyde. 
Butyl-chloral hydrate, croton-chloral hydrate, wrongly so called, 
hydrate of butyl-chloral [Butyl-chloral Hydras, B. P.), hydrous 
butyl-chloral, C 3 Ii 4 Cl 3 CH(OH) 2 (trichlorbutylidene glycol), occurs " in 
pearly white crystalline scales, having a pungent but not acid odor, 
resembling that of hydrous chloral, and an acrid nauseous taste. It 
fuses at about 172° F. (77.8° C.) to a transparent liquid, which in 
cooling commences to solidify at about 160° F. (71.1° C). Soluble 
in about 50 parts of water, in its own weight of glycerin and of 
rectified spirit, and nearly insoluble in chloroform. The aqueous 
solution is neutral or but slightly acid to litmus-paper. It does not 
yield chloroform when heated with solutions of potash or soda or 
with milk of lime." 

The Acetic Series of Acids — continued. 

Propylic or Propionic Acid (ethyl-formic acid), C 2 H 5 COOH, is 
produced by oxidation of propylic alcohol. 

Butyric or Tetrylic Acid (propyl-formic acid), C 3 H 7 COOIl, is 
formed by general methods ; also during the fermentation of cheese. 
It is found as a glyceric salt in butter (whence its name). 

Pentylic, Valerianic, or Valeric Acid, C 4 H 9 COOH. — There are 
several varieties of this acid, the valerianic acid from valerian and 
angelica-root, and that artificially formed from amylic alcohol {vide 
p. 363), being the iso-primary valerianic acid, or iso-propylacetic 
acid, CH(CH 3 ) 2 CH 2 'COOH, the normal having the constitution of 
CH 3 CH 2 CH 2 CH 2 COOH. 

Palmitic Acid, Cj 5 H 31 COOH, from soft fats ; Stearic Acid, 



LACTIC ACID. 489 

C n II.*>COOH, from suet ? tallow, and the hard fats; Cerotic Acid, 
C 26 H 53 OOOH, from beeswax ; and Melissic Acid, C 29 H 59 COOH, from 
beeswax and from canauba wax (from the leaves of Copemicia 
cerifera, a Brazilian palm), belong to the acetic series. 

Stearic Acid, HC 18 H 35 2 , is official (Acidum Stearicum, U. S. P.). 
It is a hard, bright, white solid without odor or taste, soluble in 
alcohol or ether. Melts at 69.2° C. " If 1 grm. of the acid and 1 of 
sodium carbonate be boiled with 30 cc. of water in a capacious flask, 
the resulting solution, while hot, should not be more than opalescent 
(limit of undecomposed fat)." 



The Lactic Series. 

Acids of the Lactic Series, C n H 2n (OH)COOH. — This series is 
formed of hydroxy-derivatives of the acetic series, one atom of 
hydrogen being replaced by the hydroxyl group. 

CH3COOH CH 2 (OH)COOH 

Acetic acid. Hydroxyacetic or glycollic acid. 

Though they possess only one carboxyl (COOH) group, yet, having 
an alcoholic hydroxyl group, they may sometimes form di-substitu- 
tion derivatives with the metals. 

The^ are best formed by hydrolysis of the nitriles produced on 
combining hydrocyanic acid with aldehydes or ketones ; also by 
partial oxidation of glycols by diluted nitric acid, and by acting on 
monochloro-derivatives of the acids of the acetic series by moist 
silver oxide : 

2CH 2 C1C00H + Ag 2 + H 2 = 2CH 2 OHCOOH + 2AgCl 

Monochloracetic acid. Glycollic acid. 

Carbonic Acid or Hydroxy formic Acid, OHCOOH, the first of 
this series, has been studied already. Carbamide or Urea, NH 2 *CO- 
NH 2 , the normal amide of carbonic acid, is interesting historically 
as being the first organic body synthetically produced from inorganic 
sources. (See Index, "Urea, Artificial Production of.") The acid 
amide of carbonic acid, carbamic acid, NH^COOH, occurs as an 
ammonium salt, NH^COONH^, in the ammonium carbonate of 
pharmacy. Ethyl carbamate, or Urethane, NH 2 COOC 2 H 5 , is a 
mild hypnotic. 

Glycollic Acid (Hydroxyacetic Acid), CH 2 OHCOOH, is found in 
the leaves of the Virginia creeper ; artificially it may be obtained 
by carefully oxidizing glycol and by the action of silver oxide on 
dextrose and laevulose. 

Lactic Acid (Hydroxypropionic Acid), C 2 H 4 (OII)COOH. At least 
three isomeric lactic acids are known, the fermentative lactic acid 
(ethylidene* lactic acid), CH 3 CH(OH)COOH (see p. 347), and sarco- 
lactic acid, from flesh, being those of importance. 

* Bodies having the CH3CH group are called ethylidene compounds. 
Compare chloral hydrate, trichlovethylidene glycol, CClsCH^OH^. 



490 



ORGANIC CHEMISTRY. 



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AROMATIC SERIES. 491 

The Acrylic Series. 

Acids of the Acrylic Series, C n H 2n -iCOOH. 

Acrylic Acid, C 2 H 3 COOH or CH(CH 2 )COOH, is formed by oxidiz- 
ing acrolein (acrylic aldehyde ; see Glycerin) by silver oxide. 

Crotonic Acid, or Methacrylic Acid, C 3 H 5 COOH or CH(CHCH 3 )- 
COOH, formerly supposed to be a constituent of croton oil, may be 
formed by oxidizing crotonic aldehyde, and by acting on allyl 
cvanide, C 3 H 5 CN, by water and hydrochloric acid : C 3 H 5 CN + 
2H 2 + HC1 = C 3 H 5 COOH + NH 4 C1. 

Oleic Acid, C 18 H 34 2 , or CH(C 16 H 32 )COOH, is found as a glyceric 
salt in many fats and oils. 

Preparation. — Olive oil is saponified with caustic potash, and 
the resulting soap decomposed by tartaric acid, which liberates 
oleic and stearic acids. The oleic and stearic acids are heated 
with lead oxide, forming lead oleate and stearate, the former 
being dissolved out from the latter by ether. The ether is 
evaporated and the lead oleate treated with hydrochloric acid, 
which liberates the oleic acid. 

Elaidic Acid (isomeric with oleic acid) is formed by passing 
nitrogen peroxide into oleic acid ; it is more stable than oleic acid, 
distilling unchanged. 

The Benzoic or Aromatic Series. 

Acids of the Benzoic or Aromatic Series, C n H 2n -7COOH. — The 
acids of this series are formed by oxidizing hydrocarbons, by oxida- 
tion of alcohols of the benzylic series, and by acting on the cyanides 
of the members of the benzene series. All the acids of this series, 
with the exception of benzoic acid, possess many isomers. 

Benzoic Acid, C 6 H 5 COOH, occurs naturally in gum benzoin (gum 
benjamin), which contains from 12 to 15 per cent., the rest being 
mainly composed of two resins having the formulae C 40 H 46 O 9 and 
C 30 H 40 O 5 . Benzoic acid may be obtained by oxidizing benzoic 
aldehyde, C 6 H 5 COH, which may be prepared from trichloromethyl- 
benzene. (See Toluene, p. 431.) Benzoene (toluene), C 6 H 5 CH 3 , may 
be directly oxidized into benzoic aldehyde, the methyl group (CH 3 ) 
being resolved into COOH, evidence that benzoic acid is really a 
benzoene derivative, not a phenoene derivative. (For other modes 
of obtaining benzoic acid artificially, see p. 335.) It may also be 
produced from hippuric acid (benzamidacetic acid), p. 340. Benzoic 
acid heated with lime yields benzene : 

C 6 H 5 COOH -f CaO = C fi H 6 + CaC0 3 

Benzoic acid. Calcium oxide. Benzene. Calcium carbonate. 

Benzoic Aldehyde, or Benzaldehyde, C 6 H 5 COH, forms the greater 
part of oil of bitter almonds. (See Amygdalin, p. 499.) It is a 
colorless liquid, soluble in 30 parts of water and in all proportions 
in ether and alcohol. With acid potassium sulphite it, like other 
aldehydes, forms a crystalline compound, CgH^COH/NaHSOg. 



492 ORGANIC CHEMISTRY. 

Benzoyl Chloride, C 7 H 5 0C1, results from the action of chlorine on 
benzaldehyde (formerly termed benzoyl hydride, C 7 H 5 OH), or from 
the action of phosphorus pentachloride on benzoic acid {benzoyl 
hydrate, C 7 H 5 OOH). Benzaldehyde also results from the oxidation 
of the benzyl alcohol (C 7 H 7 OH) of balsam of Peru. 

The other acids of this series are not very important. 

The Hydroxybenzoic Series. 

Acids of the Hydroxybenzoic Series, C n H 2n -80H - COOH. — Just as 
the acids of the lactic series are related to the acetic series, so are 
the acids of the hydroxybenzoic (or salicylic) series related to the 
benzoic series. 

CH 3 COOH CH 2 OHCOOH 

Acetic acid. Hydroxyacetic or glycollic acid. 

C 6 H 5 COOH C 6 H 4 OHCOOH 

Benzoic acid. Hydroxybenzoic or salicylic acid. 

Salicylic or Hydroxybenzoic Acid, C 7 H 6 3 or C 6 H 4 OHCOOH 
{Acidum Salicylicum, U. S. P.). Natural and artificial salicylates 
of methyl are described on p. 407. It also occurs in several species 
of violet (Mandelin). Salicylic acid may be made by the oxidation 
of salicylic aldehyde {vide infra), or by the action of carbonic acid 
on phenol or carbolic acid (Kolbe). To accomplish this, the phenol 
is mixed with caustic soda, forming sodium-phenol or sodium car- 
bolate, C 6 H 5 ONa. The sodium-phenol is then saturated with car- 
bonic acid at the ordinary temperature, by which sodium phenyl- 
carbonate is produced. The latter on being heated in closed vessels 
is transformed into sodium salicylate, from which salicylic acid may 
be obtained by the action of hydrochloric acid, and purification by 
recrystallization from alcohol. It appears to be identical with the 
natural acid. 

C 6 H 5 -ONa + C0 2 = C 6 H 5 OCOONa 

Sodium-phenol or Sodium phenyl-carbonate. 

sodium carbolate. 

C 6 H 5 OCOONa = C 6 H 4 OH'CO'ONa 

Sodium Sodium 

phenyl-carbonate. salicylate. 

C 6 H 4 OH-COONa + HC1 = C 6 H 4 OHCOOH + NaCl 

Sodium salicylate. Salicylic acid. 

Phenyl Salicylate. 

Synonyms. — Salicylate of Phenyl; Salicylic Phenol. 

Salol, C 6 H 4 OHCOOC 6 H 5 , is a new antiseptic, antipyretic, anti- 
rheumatic remedy. It is a white crystalline powder with a slight 
aromatic odor, soluble in alcohol, ether, chloroform, and the fixed 
and volatile oils, insoluble in water. When heated on platinum- 
foil it burns completely away. 

Salol, U. S. P., should conform to the following tests : On warm- 
ing a small portion of the substance with enough sodium hydrate 



SALICYLIC ACID. 493 

to dissolve it, and then supersaturating the liquid with hydrochloric 
acid, salicylic acid will separate, and the odor of phenol will become 
perceptible. In an alcoholic solution bromine-water, added in 
excess, produces a white precipitate. On adding a few drops of 
very dilute ferric chloride (1 in 200) to 10 cc. of an alcoholic solution 
(1 in 50) of salol, the liquid will acquire a violet tint. If, however, 
a few drops of the alcoholic solution be added to 10 cc. of the ordinary 
diluted ferric chloride, a whitish cloudiness, but no color, will be 
produced on agitation. On shaking 1 grm. of salol with 50 cc. of 
water the nitrate should not be affected by very dilute ferric chloride 
(absence of uncombined carbolic or salicylic acid), nor by barium 
chloride (absence of sulphate or phosphate), nor by silver nitrate 
(absence of chloride). 

Table showing the Relations between the Benzoic and 
Hydroxybenzoic Acids. 

Benzoic acid , C 6 H 5 COOH. 

Hydroxybenzoic or salicylic acid . C 6 H 4 OH-COOH. 

Dihydroxybenzoic acid C 6 H 3 (OH) 2 -CO'OH. 

Trihydroxybenzoic or gallic acid . CgH^OH^-CO^OH. 

Salicylic acid, like carbolic acid, is a powerful antiseptic, but is 
free from the taste and smell of carbolic acid. It is only slightly 
soluble in cold water, but readily soluble in hot water, alcohol, 
ether, and in aqueous solutions of such alkali-metal salts as borax, 
sodium phosphate, or potassium citrate, which it converts into acid 
salts with formation of a salicylate. A similar antiseptic, cresotic 
acid (hydroxytoluic acid, C 6 H 3 OHCH 3 'COOH), is similarly obtained 
from cresol or cresylic acid, C 6 H 4 OHCH 3 . Ferric chloride strikes 
a violet coloration with both salicylic and cresotic acids. Both acids 
have antipyretic powers. The true salicylates of the alkali-metals, 
and probably therefore the cresotates, are very feeble antiseptics. 
Sodium salicylate (Sodii Salicylas, U. S. P.), NaC 7 H 5 3 , the old 
salicylate of soda, made by neutralizing salicylic acid with sodium 
hydrate or carbonate, forms small, nearly colorless, lamellar crystals, 
soluble in alcohol and readily soluble in water. Carbolic acid often 
containing cresylic acid, commercial salicylic acid may contain 
cresotic acid. An alcoholic solution of salicylic acid allowed to 
evaporate spontaneously, exposure to dust being avoided, should 
leave a white residue free from color even at the points of the 
crystals. Salicylic acid yields colored substances on being nitrated 
and etherified, etc. Iodosalicylic acid and di-iodosalicylic acid, 
C-H 5 I0 3 and C 7 H 4 I 2 3 , are used in medicine. 

Salicylic Aldehyde, or Hydroxybenzoic Aldehyde, C 6 H 4 OH'COH 
(Salicylous Acid, Hydride of Salicyl). — Found in the essential, oil of 
meadow-sweet ( Spirea ulmaria) ; also obtained by the oxidation of 
saligenin. (See p. 507.) It may be artificially formed by the action 
of chloroform on sodium-phenol. 

Preparation. — Mix 10 parts of phenol with 20 parts of 
sodium hydrate dissolved in 30 parts of water in a flask having 

22 



494 ORGANIC CHEMISTRY. 

an upright condenser, and gradually add 20 parts of chloro- 
form. After heating the flask on a water-bath until all chloro- 
form has disappeared, add excess of hydrochloric acid, when a 
red-violet oil will rise to the surface. Pour the contents of the 
flask into a retort, and pass steam through it till no more alde- 
hyde comes over. The reaction is as follows : 

C 6 H 5 ONa+3NaOH+CHCl 3 = C 6 H 4 ONaCOH+3NaCl+2H 2 0. 

Sodium Chloroform. Sodium salicylic 

phenol. aldehyde. 

This, treated with hydrochloric acid, gives — 

C 6 H 4 ONaCOH + HC1 = C 6 H 4 (OH)COH + NaCl. 

Sodium salicylic Salicylic aldehyde, 

aldehyde. 

The oil which passes over (orthohydroxy ben zoic aldehyde) may be 
purified from phenol (with which it is always contaminated) by 
treating with acid sodium sulphite, which forms a compound with 
the aldehyde, leaving the phenol, which may be removed by dissolv- 
ing in ether. An isomeric salicylic aldehyde (parahydroxybenzoic 
aldehyde) is formed with the ortho-aldehyde, and remains dissolved 
in the water in the retort, from whence it is precipitated on cooling. 
Coumarin, C 9 H 6 2 (the principle of the Tonka bean), may be 
obtained by acting on the sodium-derivative of salicylic aldehyde 
with acetic anhydride and sodium acetate (Perkin). 

The Tr (hydroxy benzoic Series. 

Acids of the Series C n H 2n _ 10 (OH)3COOH.— Gallic Acid, or Tri- 
hydroxybenzoic Acid, C 6 H 2 (OH) 3 COOH. (See p. 360.) By the 
elimination of one molecule of water from two molecules of gallic 
acid, tannic acid is produced. 

x ( COOH 

rTT rcooH) c 6 hJ(oh) 2 

+ H 2 
nn (COOHl (CO j 

c A{(OH).) caJ 

Gallic acid. Tannic acid. 

Gallic acid (or tannin ; see p. 360) by heat yields pyrogallol or 
pyrogallic acid and carbonic anhydride. 

C 6 H 2 (OH) 3 COOH = C 6 H 3 (OH) 3 + C0 2 . 

The Cinnamic Series. 

Acids of the Cinnamic Series, C u H 2 n-9COOH.— Cinnamic acid, 
C 8 H 7 COOH, may be obtained from the balsams of Tolu, Peru, and 
storax. It may be made artificially by a process analogous to that 
by which coumarin is, as just stated, prepared from salicylic alde- 
hyde. 



DIBASIC ACIDS. 495 

1. Balsam of Peru [Balsamum Peruvianum, U. S. P.), an exuda- 
tion from the trunk of Myroxylon Pereirm, is a mixture of oily mat- 
ter with about one-quarter or one-third resinous matter and 6 per 
cent, of cinnamic acid. The oil, by fractional distillation in an 
atmosphere of carbonic acid gas and under diminished pressure, 
furnishes benzyl-hydrate, or benzylic alcohol (C 6 H 5 CH 2 OH), benzyl 
benzoate (C 6 H 5 CO'OC 7 H 7 ), and benzyl cinnamate (C 8 H 7 C(>O.C 7 H 7 ), or 
cinnamein (Kraut). By action of alcoholic solution of potash it 
yields potassium benzoate and cinnamate and benzylic alcohol ; also 
cinnamic alcohol (C 8 H 7 CH 2 OH), otherwise known as peruvine or sty- 
rone; it also often holds in solution metacinnamein or styracin 
(C 18 H 16 2 ), isomeric with cinnamic aldehyde (C 8 H 7 COH). The resin 
of balsam of Peru seems to result from the action of moisture on the 
oil. Any admixture of resin, oil, storax, benzoin, or.copaiva with 
balsam of Peru is detected by mixing 6 grains of slaked lime with 
10 drops of the balsam, when a soft product results if the specimen 
be pure, but hard if impure ; further, the mixture, on being warmed 
until volatile matter is expelled and charring commences, gives no 
fatty odor. 2. Balsam of Tolu {Balsamum Tolutanum, U. S. P.) is 
an exudation from the trunk of Myroxylon Toluifera ; in composi- 
tion it closely resembles balsam of Peru, but is more susceptible of 
resinification. It contains benzyl benzoate and cinnamate, cinnamic 
acid, a little benzoic acid (Busse), and about 1 per cent, of a volatile 
hydrocarbon, tolene, C 10 H 16 . The cinnamic-acid crystals may be 
seen with a lens when a little of the balsam is pressed between two 
warmed pieces of glass. Old hard balsam of Tolu is a convenient 
source of cinnamic acid, which may be extracted by the same pro- 
cess as that by which benzoic acid is obtained from benzoin — namely, 
ebullition with alkali, nitration, and precipitation by hydrochloric 
acid. 3. Storax (Styrax, U. S. P.) is an oleo-resin obtained from 
the Liquidambar orientate. It contains a volatile oil termed styrol, 
cinnamene, or cinnamol (C 8 H 8 )— which possibly (Berthelot) is con- 
densed acetylene, 4C 2 H 2 — cinnamic acid, styracin, or cinnamyl cin- 
namate (C 8 H 7 COOC 9 H 9 ), and a soft and a hard resin. Styrol differs 
from similar hydrocarbons in being converted into a polymeric solid, 
termed metastyrol or draconyl, on heating to about 400° F. For 
medicinal use storax (Styrax Prceparatus, B. P.) is purified by solu- 
tion in alcohol, filtration, and removal of the alcohol by distillation. 
By oxidation with red potassium chromate and sulphuric acid it 
vields an odor resembling that of essential oil of bitter almonds. 



Dibasic Acids. 

Dibasic Acids are acids having two carboxyl (COOH) groups in 
the molecule. 

The Succinic Series. 

Acids of the Succinic Series, C n H 2n (COOH) 2 .~These acids may 
be formed by the oxidation of glycols or by the action of water and 
hydrochloric acids on the cyanides of the olefines, obtained by acting 
on the olefine dibromo-additive derivatives by potassium cyanide. 



496 ORGANIC CHEMISTRY. 

Oxalic Acid, C 2 4 H 2 or (COOH) 2 , is the first of this series. It 
may be obtained by oxidizing glycol, C 2 H 4 (OH) 2 : 

CH 2 OH COOH 

| + 20 2 = | + 2H 2 

CH 2 OH COOH 

Glycol. Oxalic acid. 

Also by the action of carbonic anhydride on metallic sodium : 
2C0 2 + Na 2 = C 2 4 Na 2 

Carbonic anhydride. Sodium. Sodium oxalate. 

(For other methods see Oxalic Acid, p. 316.) 

Oxamide, C 2 2 (NH 2 ) 2 , the analogue of urea — carbamide, CO(NH 2 ) 2 
— is formed on mixing ethyl oxalate with ammonia or by passing 
cyanogen into aqueous hydrochloric acid, C 2 N 2 + 2H 2 = (CONH 2 ) 2 . 

Succinic Acid, C 2 H 4 (COOH) 2 .— (See p. 356.) 

The Malic Series. 

Acids of the Malic Series, C I1 H 2n _ 1 OH(COOH) 2 .— Malic or hy- 
droxysuccinic acid, C 2 H 3 (OH)(COOH) 2 , is obtained artificially by 
acting on bromosuccinic acid, C 2 H 3 Br(COOH) 2 , with moist silver 
oxide, the bromine being replaced by hydroxyl. It is contained in 
unripe mountain-ash berries, morello cherries, etc. (See p. 348.) 

Asparagin (amidosuccinamic acid), ^HgNHg^/^nw 2, (See p. 
349.) KjVvn 

The Tartaric Series. 

Acids of the Tartaric Series, C n H 2n _ 2 (OH) 2 (COOH) 2 . — Tartaric 
Acid (dihydroxysuccinic acid), C 2 H 2 (OH) 2 (COOH) 9 , may be obtained 
by oxidizing erythrite, C 2 H 2 (OH) 2 (CH 2 OH) 2 . (See p. 465. _ For 
other modes of formation see p. 318.) There are four isomeric tar- 
taric acids, differing by their action on a ray of polarized light. 

The Phthalic Series. 

Acids of the Phthalic Series, C n H 2n _ 8 (COOH) 2 .— Phthalic Acid, 
C 6 H 4 (COOH) 2 , is obtained by the oxidation of naphthalene and 
naphthalene tetrachloride, or a mixture of benzene and benzoic acid. 
By distillation it forms phthalic anhydride, C 8 H 4 3 , and this when 
heated with phenol and sulphuric acid yields phenolphthalein 
(B. P.), a light-yellow crystalline powder, which when dissolved in 
alcohol is used in alkalimetry for its property of turning brilliant 
red with the slightest excess of alkali. There are three phthalic 
acids : phthalic acid or orthophthalic acid, C 6 H 4 COOHCOOH (0) : 
isophthalic acid or metaphthalic acid, C 6 H 4 COOHCOOH (w) •, and 
terephthalic acid or paraphthalic acid, C 6 H 4 COOHCOOH (i)) . (See 
p. 455.) 

Tribasic Acids. 

Tribasic Acids, having three carboxyl (COOH) groups in the 
molecule. — Tricar ballylic Acid, or propane-tricarboxylic acid, C 3 H 5 - 



RELATIONS OF SERIES OF ACIDS. 



497 



a 





O 




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jp W 


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g B g- 

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H 






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05- 






wg; 


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■ Oo" 


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498 ORGANIC CHEMISTRY. 

(COOH) 3 , is the first of these series ; its hydroxy-derivative is citric 
acid, C 3 H 4 (OH)(COOH) 3 , (hydroxy-propane-tricarboxylic acid), found 
in fruits. It has already been described. (See p. 323.) 

Other Polybasic Acids. 

Tetrabasic acids, as pyromellitic acid, C 6 H 2 (COOH) 4 , and hexabasic 
acids, as mellitic acid, C 6 (COOH) 6 , are known. 



QUESTIONS AND EXERCISES. 

Give general methods for the formation of aldehydes and acids. — How 
is acetaldehyde prepared?— Describe the reactions that occur iu the 
manufacture of chloral and chloral hydrate. — What is the nature of the 
action of alkalies on chloral hydrate ? — Mention the characters of pure 
and impure chloral hydrate. — What relation lias valerianic acid to amylic 
alcohol? — Give the relations between the acetic and lactic series of acids. 
— To what series do the following acids belong: Oleic, butyric, oxalic, 
and citric ? — How is benzoic acid prepared ? — Give the differences between 
balsams of Peru and Tolu and gum benzoin. — How is oil of bitter almonds 
prepared? and how can it be distinguished from so-called artificial oil 
of bitter almonds? — Give artificial methods of preparing salicylic alde- 
hyde and acid. — Give systematic names of tartaric, succinic, carbonic, 
salicylic, and citric acids. 



Ketones. 

Just as primary alcohols on losing hydrogen yield aldehydes, so 
secondary alcohols (see p. 437) on losing hydrogen yield ketones : 

C n H 2n + 1 CH 2 OH -H 2 = C a H 2a + 1 COH 
(C n H 2n + 2 CHOH — H 2 = C n II 2n + x ) 2 CO 

Like aldehydes, ketones are converted by nascent hydrogen into 
the corresponding alcohols. Like aldehydes, ketones form crystal- 
line compounds with acid" sulphites. While, however, aldehydes by 
oxidation yield corresponding acids, ketones break up and yield 
acids whose molecules have a smaller number of carbon atoms. 

Acetone, C 3 H 6 0, or Dimethyl-ketone, (CH 3 ) 2 CO or CH 3 C0CH 3 , the 
original and best known of the class, may be obtained by strongly 
heating calcium acetate, carbonate remaining. The calcium salts of 
other fatty radicals split up in a similar manner (hence perhaps the 
name, from nio, keo, I split, and the original acetone), yielding other 
ketones, as propione, butyrone, valerone, etc. The mixed calcium 
salts give corresponding ketones. Thus acetate and caprate yield 
methyl-nonyl ketone, CH 3 — CO — C 9 H 19 , the chief natural constituent 
of oil of rue. Acetophenone, or phenylmethyl ketone, C 6 H 5 'CO'CH 3 , 
is known as hypnone. 

(CH 3 COO) 2 Ca = (CH 3 ) 2 CO -f CaC0 3 

Calcium acetate. Acetone. Calcium carbonate. 



GLUCOSIDES. 499 

Note. — There are many organic substances the composition of 
which has been established and the characters of which are definite, 
whether basic, acid, or neutral, but whose constitution is still so 
questionable that they cannot yet be classified with the hydrocarbons 
and derivatives of hydrocarbons. These are the glucosides, alka- 
loids, albumenoids, certain coloring matters, etc. They are described 
in the following pages. 



THE GLUCOSIDES. 

Source. — The glucosides are certain proximate vegetable principles 
which, by ebullition with dilute acid or other method of decompo- 
sition, take up the elements of water and yield glucose, accompanied 
by a second substance, which differs in each case according to the 
body operated on. Several of the glucosides which are of pharma- 
ceutical interest will now be considered. Tannin has also been said 
to be a glucoside ; it has been described among the Acids. 

There are indications that all glucosides may be regenerated from 
the bodies into which they are thus converted. 

Note on Nomenclature. — The first syllable of the names of gluco- 
sides and neutral principles generally is commonly given in allusion 
to origin ; the last syllable is in, which sufficiently distinguishes 
them as a class. 

Absinthin (C 15 II 10 O 4 ), the bitter principle of Artemisia Absinthium, 
or wormwood, yields, when boiled with acids, glucose, volatile oil, 
and a resin, of the aromatic series. (The liqueur termed absinthe is 
spirit of wine flavored with natural oil of wormwood, colored by 
chlorophyll, and slightly sweetened.) 

Amygdalin (C 2 oH 27 NO n ,3H 2 0). — This body, obtained by 
Robiquet and Boutron-Charlard in 1830, was the first-dis- 
covered glucoside (Liebig and Wohler, 1837). It is a white 
crystalline substance existing in the bitter (Amygdala Amara, 
U. S. P.), but not in the sweet almond (Amygdala Didcis, U. S. 
P.). About 2 per cent, is readily extracted by strong alco- 
hol from the cake left when the fixed oil has been expressed 
from bitter almonds. From the concentrated alcoholic solution 
ether precipitates the amygdalin. 

Make an emulsion of two or three sweet almonds by bruising 
and rubbing them with water, and notice that it has no odor 
of essential oil of bitter almonds ; add a grain or two of amyg- 
dalin : an odor of essential oil of bitter almonds is at once 
developed. Bruise two or three bitter almonds and rub with 
water : the volatile oil is again developed (Oleum Amygdalse 
Amarse, U. S. P.). Sp. gr. 1.060 to 1.070. 

Bitter-almond Water (Aqua Amygdalae Amaroe, U. S. P.) is made 
by filtering a mixture of 1 part of the oil with 999 parts of distilled 
water. The source of the benzaldehyde, or essential oil of bitter 



500 ORGANIC CHEMISTRY. 

almonds, in these reactions is the amygdalin, which, under the influ- 
ence of synaptase or emulsin (a nitrogenous, casein-like ferment 
existing in both bitter and sweet almonds), splits up into the essen- 
tial oil, hydrocyanic acid, and glucose: 

C 20 H 27 NO n + 2H 2 = C 6 H 5 COH + HON + 2C 6 H 12 6 

Amygdalin. Water. Benzaldehyde. Hydro- Glucose. 

cyanic acid. 

As each molecule of amygdalin yields one of hydrocyanic acid, a 
simple calculation shows that 17 grains (mixed with emulsion of 
sweet almonds) will be required to form 1 grain of real hydrocyanic 
acid, a quantity equivalent to 50 minims of the diluted hydrocyanic 
acid of the British Pharmacopoeia. The hydrocyanic acid is prob- 
ably in chemical combination with the oil to the extent of about 5 
per cent. According to Linde, the occurrence of the benzaldehyde 
is preceded by the formation of benzaldehydcyanhydrin (C 6 H 5 CH- 
(OH)CN). The emulsin and amygdalin occur in different parts of 
the bitter almond. 

Test.— The reaction between synaptase and amygdalin is appli- 
cable as a test of the presence of one by the addition of the other, 
even when mixed with much organic matter. 

Jacobsen obtains true benzaldehyde artificially from benzodi- 
chloride (dichloromethylbenzene, C 6 H 5 CHC1 2 ), one of the dichloro- 
toluenes, by heating with glacial acetic acid and zinc chloride with a 
little water. 

Cherry-laurel Water (Aqua Laurocerasi, B. P., by distillation 
with water from Laurocerasi Folia, B. P.) contains hydrocyanic 
acid, derived from a reaction similar to, indeed probably identical 
with, that described above, for bitter almond oil is simultaneously 
produced. But the proportion of amygdalin or analogous body in 
cherry-laurel leaves is most variable ; hence normally the strength 
of the water is highly uncertain. The British Pharmacopoeia, how- 
ever, directs that it shall contain 0.1 per cent, of real hydrocyanic 
acid, it being strengthened by the addition of hydrocyanic acid, or, 
if necessary, diluted by the addition of distilled water, until it has 
the prescribed strength. 

Linseed yields a glucoside, linamarin, related to amygdalin; for it 
yields glucose and hydrocyanic acid on hydrolysis. 

Cortex Pruni Serotince. — The recently dried wild-cherry bark also 
furnishes by distillation an essential oil and hydrocyanic acid. 
Quince-seeds also (Pyrus Cydonia). The wild black cherry bark 
(Prunus Virginiana, U. S. P.), collected in autumn, contains amyg- 
dalin. 

Caution.— Essential oil of almonds is of course highly poisonous. 
The purified oil or benzaldehyde is almost innocuous ; it is obtained 
on distilling the crude oil with milk of lime and ferrous chloride 
and drying the product by shaking with fused calcium chloride. 
The so-called "artificial oil of bitter almonds" or " nitrobenzol " 
[C 6 H 5 N0 2 ], when taken in quantity, has been known to produce 
death. The presence of nitrobenzol in oil of bitter almonds is de- 
tected by adding a little of the oil to a mixture of zinc and diluted 
sulphuric acid, shaking well, setting aside for an hour or two, filter- 



GLUCOSIDES. 501 

ing off the clear liquid, and adding a little potassium chlorate ; a 
violet color (actual mauve) is produced. The reaction is due to the 
formation of phenylamine or aniline. (See p. 431.) Or the speci- 
men may be shaken with sodium bisulphite to fix the benzaldehyde 
(for all such aldehydes form a compound with sodium bisulphite), 
and then with ether, which dissolves out, and on evaporation will 
yield, the nitrobenzol. 

Arbutin (C 12 H ]6 7 ) and Methyl-arbutin (C 13 H 18 7 ) are contained in 
the leaves of Arctostaphylos Uva Ursi, Chimaphila umbellata ( Chi- 
maphila, U. S. P., or Pipsissewa), and many ericaceous plants. They 
are bitter neutral bodies occurring in acicular crystals, and resolva- 
ble by acids into hydroquinone (C 6 H 6 2 ) and glucose, and by gentle 
oxidation into quinone (C 6 H 4 2 ) and formic acid. Ericolin (C 34 H 56 21 ) 
is another bitter glucoside in bearberry-leaves. 

Bryonin (C 48 H 80 O 19 , Walz). — The colorless, bitter, indistinctly 
crystalline principle of bryony {Bryonia, U. S. P., the root of 
Bryonia alba and Bryonia dioica). 

Cathartic Acid. — " The glucoside acid that now is known to 
confer on the senna of Alexandria (from Cassia acutifolia) and of 
India (from Cassia elongata) (Sen?ia, U. S. P.) its purgative property 
has been named by its discoverers (Dragendorff and Kubly) cathartic 
acid. Its formula has been stated as C 180 H 192 N 4 SO 82 (but A. Gensz 
more recently states it to be C 30 H 36 NO 15 ). It is insoluble (?) in 
water, strong alcohol, and ether, but enters readily into either solu- 
tion when combined with alkaline and earthy bases, in which state 
it exists in senna. Its ammonium salts give brownish flocculent 
precipitates with salts of silver, tin, mercury, copper, and lead. 
Antimonial salts, tannin, and yellow and red prussiates have no 
effect upon it. Alkalies, aided by heat, act destructively upon it. 
Boiled with a mineral acid, it splits into a peculiar kind of glucose 
and an acid that has been named cathartogenic ; its formula is said to 
be C 132 H 116 N 4 S0 44 . The natural cathartate occurring in senna is pre- 
pared by partially precipitating by strong spirit a watery infusion 
of senna, concentrated to a syrupy state by evaporation in vacuo. 
The filtrate is now treated with a much larger bulk of absolute 
alcohol, and the precipitate thus obtained is purified by repeated 
solution in water and precipitation by alcohol. To obtain the pure 
acid advantage is taken of its colloidal properties ; the crude cathar- 
tate is dissolved in moderately strong hydrochloric acid, and sub- 
jected to dialysis on a diaphragm of parchment paper. The min- 
imum dose of this pure acid was found to be about 1J grains, which 
caused several stools with decided griping." 

" The cathartic combinations that I have made are — the cathartate 
of ammonium, prepared from cathartate of lead by my original pro- 
cess, and the mixed cathartates, prepared according to Dragendorffs 
method as modified by myself. Of the former nearly pure salt I 
have found 3f grains to purge fairly as to amount, but slowly as to 
time and with considerable griping. Of the latter, 7j grains purged 
violently with much griping and sickness, which continued through 
the greater part of the day. It obviously would be improper to 
combine senna with any of its metallic precipitants should such be 
22* 



502 ORGANIC CHEMISTRY. 

desired, which is not likely. It is here satisfactory to observe that 
the cathartate of magnesium is soluble, and that the old-fashioned 
black draught agrees with new-fashioned science" (Groves). 

Buckthorn Juice (Rhamni Succus, B. P. 1867) owes its cathartic 
properties to a substance apparently identical with cathartic acid. 
Possibly the purgative properties of the bark of the Rhamnus Fran- 
gula (Frangula, U. S. P.), black alder, buckthorn, also are due to 
cathartic acid. 

Colocynthin (C 56 H 84 23 ?). — This substance is the active bitter and 
purgative principle of colocy nth-fruit ( Colocynthidis Pidpa, U. S. P.) : 
it is soluble in water and alcohol, but not in ether. By ebullition 
with acids it furnishes glucose and a resinoid body. 

Convolvulin. (See Jalapin.) 

Cotoin (C 22 H 18 6 ) appears to be the chief active principle of coto- 
bark, a Bolivian remedy for diarrhoea. A similar bark, false 
coto or paracoto, contains paracotoin, C 19 H 12 6 , and hydrocotoin, 

C i5H u 4 - 

Daphnin (C 31 H 34 19 ) is the crystalline glucosicle of the bark of 
Daphne Mezereum (Mezerei Cortex, B. P.). Boiled with dilute acids, 
it yields daphnetin (C 19 H 14 9 ) and glucose. The acrid principle of 
mezereon is resinoid. 

Digitalin (C 27 H 45 15 , Kosmann ; C 5 H 8 2 , Schmiedeberg). — This is 
an active principle of the foxglove, Digitalis purpurea (Digitalis, 
U. S. P.). On boiling a grain of digitalin with diluted sulphuric 
acid for some time, flocks of digitaliretin (C 15 H 25 5 ) separate, and 
glucose may be detected in the liquid. 

C 27 H 45 15 + 2H 2 = C 15 H 25 5 + 2C 6 H 12 6 

Digitalin. Water. Digitaliretin. Glucose. 

Properties. — Digitalin occurs " in porous mammillated masses or 
small scales, white, inodorous, and intensely bitter, readily soluble 
in spirit, but almost insoluble in water and in pure ether ; dissolves 
in acids, but does not form with them neutral compounds ; its solu- 
tion in hydrochloric acid is of a faint yellow color, but rapidly 
becomes green. It leaves no residue when burned with free access 
of air. It powerfully irritates the nostrils and is an active poison." 
— B. P. 1867. According to Pettenkofer, "an intense red color is 
produced if a trace of digitalin dissolved in water is mixed with 
a weak aqueous solution of inspissated bile and sufficient oil of 
vitriol added to raise the temperature to 1 58° F." Moistened with 
sulphuric acid and the liquid exposed to the vapor of bromine, a 
violet color is produced. 

Process. — The process for the preparation of digitalin consists in 
dissolving the glucoside out of the digitalis-leaf (Digitalis Folia, 
B. P.) by alcohol, recovering the alcohol by distillation, dissolving 
the residue in water by the help of a small quantity of acetic acid, 
removing much of the color from the solution by animal charcoal, 
neutralizing most of the acetic acid by ammonia, precipitating the 
digitalin by tannic acid (with which it forms an insoluble compound), 
washing the precipitate, rubbing and heating it with spirit and lead 
oxide (which removes the acid in the form of insoluble lead tannate), 



GLUCOSIDES. 503 

again decolorizing by animal charcoal, evaporating to dryness, wash- 
ing out impurities still remaining by ether, and drying the residual 
digitalin. In this form digitalin is uncrystallizable and somewhat 
indefinite. 

Pure Digitalin (?). — On treating commercial digitalin with chloro- 
form an inert substance remains undissolved. The solution yields 
pure digitalin on evaporation ; it may be crystallized from spirit in 
radiating needles (Nativelle). The therapeutic effect of the pure 
substance is identical with that of the preparations of digitalis, but 
more constant in its action, and, of course, intensely powerful. 

Digitoxin (C 31 H 33 7 ) (C 31 H 32 7 , Dragendorff) is a highly poisonous 
substance extracted from foxglove by Schmiedeberg. The same 
chemist regards commercial digitalin from foxglove-seeds as com- 
posed of varying proportions of three glucosides — namely, pure 
active digitalin (C 5 H 8 2 ), digitonin (C 31 H 52 17 ) (closely allied to 
saponin), and digitalein, with inactive digitalin or digitin. Kiliani 
says that Schmiedeberg' s digitalein is a mixture, and that his " digi- 
talin," which is a pure but uncrystallizable glucoside, C 5 H 8 2 , is the 
true active principle. Digitonin, C 27 H 46 O u (Kiliani), yields on 
hydrolysis digitogenin, C 15 H 24 3 , galactose, C 6 H 12 6 , and dextrose, 

Elaterin (C 20 H 28 O 5 ). — Boil elaterium (Elaterium, B. P.), 
the dried sediment from the juice of the squirting cucumber 
fruit, Ecballium Elaterium (Ecballii Eructus, B. P.), with chloro- 
form, filter, evaporate, wash with ether the precipitated elaterin, 
recrystallize it from chloroform, and again wash, the crystals 
with ether. The product, the official Elaterinum, U. S. P., 
occurs in small hexagonal plates or prisms. A trituration of 
elaterin is official (Trituratio Elaterini, U. S. P.). It is a mix- 
ture of 1 part of elaterin with 9 of sugar of milk. 

Elaterin is probably not a true glucoside. It does not always 
respond to the test for glucose after boiling with acids, and when it 
does the reaction is possibly due to prophetin, a glucoside stated by 
Walz to be present in elaterium. 

Elaterin is the active principle of the so-called elaterium. Elate- 
rium occurs in light friable greenish-gray cakes. Good specimens 
of this drug should yield not less than 20 per cent, of elaterin by 
the above process. 

Test. — A little is placed in a watch-glass with a drop of liquefied 
carbolic acid, and then two drops of strong sulphuric acid : a carmine 
color is developed (Lindo). 

Frangulin, C 21 H 20 9 , is a glucoside found in the bark of Rhamnus 
frangula. It is decomposed on hydrolysis into emodin, C 15 H 10 O 5 , 
and an unfermen table sugar, rhamnose, C 6 H 12 5 . 

G-entiopicrin, or Gentian Bitter (C 20 H 30 O 12 ), the neutral crys- 
talline principle of the root of Gentiana lutea (Gentiance Radix, 
B. P.). It is soluble in water and weak spirit. Alkalies decom- 
pose it. Dilute acids convert it into gentiogenin and glucose. 
Gentian-root also contains a variety of tannin and a crystalline acid 



504 ORGANIC CHEMISTRY. 

(HC 14 H 9 5 ) termed gentianic or gentisic acid or gentisin. Fused 
potash, etc. gives with the latter an acid (C 7 H 6 4 ), which has also, 
unfortunately, been called gentisic acid. 

Glycyrrhizin (C 24 H 36 9 , Gorup-Besanez), or Glycyrrhizic Acid 
(C 44 H 63 N0 18 , Habermann). — Liquorice-root (Glycyrrhiza, U. S. P.), 
in addition to uncrystallizable sugar, contains 3 or 4 per cent, of a 
sweet substance, glycyrrhizin, which, when boiled with hydrochloric 
acid or diluted sulphuric acid, yields a resinoid bitter bedy, glycyr- 
retin, and an uncrystallizable sugar resembling glucose. Glycyr- 
rhizin is only slightly, soluble in cold water, but is taken up by 
diluted alcohol containing a little ammonia {Extractum Glycyrrhizm 
Fluidum, U. S. P.) or by ammoniacal water. An infusion of the 
latter, evaporated to a pilular consistence, forms Extractum Glycyr- 
rhizce Purum, U. S. P. It is present in considerable quantity in 
the evaporated decoction (Stick Liquorice, Spanish Liquorice, or 
Solazzi Juice). The tropical substitute for liquorice is the root of 
Abrus precatorius, or Indian Liquorice (Abri Radix, P. I.), the 
hunch or ganj of Bengal, the ratti of Hindostan, and the jequirity 
or jequerity of Brazil, which also contains glucose and glycyrrhizin. 
The seeds yield by maceration a substance which acts as a poison 
when injected into the blood, but not when swallowed. Warden 
and Waddell regard the active principle as an albumenoid, and term 
it abrin. Bruylants and Venneman consider it to be a product of 
germination, and call it jequeritin. Bechamp and Dujardin regard 
the latter as a mixture of legumin and jequerityzymase. Glycyr- 
rhizin has considerable power of disguising nauseous flavors. 
Roussin refers the sweet taste of liquorice not to pure glycyrrhizin, 
but to a combination of glycyrrhizin with alkalies, and states that 
ammoniacal glycyrrhizin has exactly the sweetness of liquorice-root. 
The formula of this ammonium glycyrrhizate is said by Habermann 
to be (NH 4 ) 3 C 44 H 60 NO 18 . Sestini finds that the glycyrrhizin of 
liquorice-root is chiefly calcium glycyrrhizate. 

An ammoniated glycyrrhizin (Glycyrrhizinum Ammoniatum, U. S. 
P.) is directed to be prepared by precipitating a dilute ammoniacal 
percolate with sulphuric acid, washing, redissolving in ammoniacal 
water, reprecipitating, again washing, dissolving in solution of am- 
monia, and spreading on glass plates to dry until reddish-brown 
scales are obtained. 

Guaiacin. — Resin of guaiacum (Guaiaci Resina, U. S. P.), an 
exudation from the wood (Guaiaci Lignum, U, S. P.) of Guaiacum 
officinale, is probably a mixture of several substances, among which 
are guaiaretic or guaiaretinic acid (C 20 H 26 O 4 , Hlasiwetz), guaiaconic 
acid (C 38 H 40 O 10 , Hadelich), and guaiacin, a glucoside. On boiling 
guaiacum resin with diluted sulphuric acid for some time, glucose 
is found in the liquid, a green resinous substance (guaiaretin) re- 
maining insoluble (Kosmann). Most oxidizing agents, and even 
atmospheric air, especially under the influence of certain organic 
substances, produce a blue, then green, and finally a brown color 
when brought into contact with an alcoholic solution of guaiacum 
resin. 

These effects are said to be due to three stages of oxidation 



GLUCOSIDES. 505 

(Jonas). They may be observed on adding the solution to the inner 
surface of a paring of a raw potato. 

Helleborin (C 36 H 42 6 ) and Helleborein (C 26 H 44 15 ) are crystal- 
line glucosides occurring in the roots of black hellebore {Helleborus 
?iiger), or Christmas rose, and green hellebore (H. viridis), ranun- 
culaceous herbs. 

Jalapin (C 31 H 50 O 16 ) and Convolyulin (C 84 H 56 1? ). — According to 
Keyser and Meyer, jalap resin contains two distinct substances — 
convolvulin, chiefly obtained from Mexican male jalap (Ipomcea 
Orizabensis), and jalapin, most largely contained in the true jalap 
{Ipomcea purga) ; the former is soluble in ether, the latter insoluble. 
Boil jalap resin with diluted sulphuric acid for some time, and filter ; 
a substance which is probably a mixture of jalapinol (C ]3 H 24 3 ) and 
convolvulinol (C 16 H 30 O 3 ), separates ; glucose may be detected in the 
clear liquid. (It is to be regretted that the authors transpose these 
names, terming the old well-known jalapin convolvulin.) 

C 3 iH 50 O 16 + 5H 2 = C 13 H 24 3 + 3C 6 H 12 6 

Jalapin. Water. Jalapinol. Glucose. 

Jalapic Acid. — This is contained in the portion of jalap resin sol- 
uble in ether. It may also be obtained from jalapin by ebullition 
with alkalies : 

2C 31 H 50 O 16 -f 3H 2 = C 62 H ]06 O 35 

Jalapin. Water. Jalapic acid. 

Jalap resin (Resina Jalapse, TJ. S. P.) is obtained by digest- 
ing and percolating jalap-tubercles (Jalapa, U. S. P.) with spirit 
of wine, adding a little water, distilling off the spirit, pouring 
away the aqueous portion, which contains much saccharine 
matter, and washing and drying the residual resin. Jalap 
thoroughly exhausted by this process should furnish, according 
to the United States Pharmacopoeia, not less than 12 per cent, 
of resin, of which resin (Resina Jalapse, U. S. P.) not more than 
one-tenth should be soluble in ether — a test which excludes the 
so-called " Tampico " jalap, the resin of which is soluble in 
ether. The tincture of jalap is sometimes decolorized by 
animal charcoal and the evaporated product sold as "jalapin." 

Jalap resin is insoluble in oil of turpentine ; common resin 
or rosin, soluble. If the presence of the latter is suspected, 
the specimen should be powdered, digested in turpentine, the 
mixture filtered, and the nitrate evaporated ; no residue, or not 
more than yielded by the turpentine itself, should be obtained. 

Tampico jalap, from Ipomoza simulans, yields a resin which ap- 
parently is chiefly convolvulin, but sometimes contains jalapin, for 
a sample obtained by Hanbury was entirely soluble in ether, and 
another extracted by Umney was almost wholly soluble, while Evans 
purified some, half only of which was soluble. 

The Kaladana resin or pharbitisin of India (from Pharbitis Nil, 
P. I.) is a cathartic analogous to, if not identical with, resin of jalap. 



506 ORGANIC CHEMISTRY. 

Loganin, C 25 H 34 14 , is a glucoside obtained from the pulp of the 
fruit and from the seeds of Strychnos Nux Vomica, Loganiacese, by 
Dunstan and Short. Boiled with dilute sulphuric acid, it yields 
glucose and loganetin. 

Ouabain (C 30 H 46 O 12 , Arnaud, or C 30 H 52 C 14 ) is a very poisonous 
glucoside resembling strophanthin, found in arrow-poisons prepared 
from the wood of an Acokanthera and in the wood itself. 

Picrotoxin (Picrotoxinum, U. S. P.) is a crystalline bitter poison- 
ous principle (-rriKpbc, picros, bitter, and to^ikov, toxicon, poison) oc- 
curring in Cocculus Indicus, the dried fruit of Anamirta paniculata. 
Ludwig regarded it as a glucoside, but its constitution is not yet 
satisfactorily ascertained. Barth and Kretschy state that the so- 
called picrotoxin may be separated into picrotoxin proper (C 15 H 16 6 ,- 
H 2 0), which is bitter and poisonous ; picrotin (C 25 H 30 O 12 + "H 2 0), 
which is bitter, but not poisonous ; and anamirtin (C 19 H 24 O 10 ), which 
is neither bitter nor poisonous. Schmidt asserts that the original 
picrotoxin is definite, and has the formula C 30 H 34 O 13 , but that some 
solvents decompose it into picrotoxinin, C 15 H 16 6 , which is poison- 
ous, and picrotin, C 15 H 18 7 , which is not poisonous. 

Quassin (C 10 H 12 O 8 , Wiggers, or C 31 H 42 9 , Christensen), obtained 
from Quassice Lignum, B. P., is said to be a glucoside, but Oliveri 
and Denaro question the statement, and find quassin to have the 
formula C 32 H 44 10 . 

Saffranin. ( Vide Index.) 

Salicin (C 13 H 18 7 ). — This substance (Salicinum, IT. S. P.) is con- 
tained in, and easily extracted from, the bark of willow and of other 
species of Salix and of Populus. It occurs in white, shining, bitter 
crystals, soluble in 28 parts of water or 65 of spirits at common 
temperatures. 

Tests. — 1. To a small portion of salicin placed on a white 
plate or dish add a drop of strong sulphuric acid ; a deep-red 
color is produced. 

2. Boil salicin with diluted sulphuric acid for some time ; it 
is converted into saligenin or saligenol (C 7 H 8 Q2) and glucose. 
Test for the latter by the copper test. 

C ]3 H 18 7 + H 2 = C 6 H 4 (OH)CH 2 OH + C 6 H 12 6 

Salicin. Water. Saligenol. Glucose. 

3. To another portion of the liquid, carefully neutralized, 
add a ferric salt : a purplish-blue color is sometimes produced, 
due to the reaction of the saligenin and the ferric salt. The 
saligenin is, however, so rapidly decomposed by acids into sali- 
retin (C 7 H 6 0) and water that this reaction is almost valueless 
as a test. The saligenin may, however, be obtained by action 
of synaptase on salicin. 

4. Heat a mixture of about 1 part of salicin, 1 of red po- 
tassium chromate, 1J of sulphuric acid, and 20 of water in a 
test-tube ; a fragrant characteristic odor is evolved, due to the 



GLUCOSIDES. 507 

formation of salicylic aldehyde (C 6 H 4 OHCOH), an essential 
oil identical with that existing in meadow-sweet (Spir&a Ulma- 
ria) and in heliotrope. 

C 6 H 4 OHCH 2 OH + = C 6 H 4 OHCOH + H 2 

Saligenol. Nascent oxygen. Salicylic aldehyde. Water. 

Santonin (C 15 H 18 3 ). — This substance, used in Trochisci Santonini, 
U. S. P., is, apparently, the anhydride or, rather, the lactone,* of 
a weak acid (Hesse) insoluble in ammonia, but forming a soluble 
calcium salt. Indeed, by boiling santonin for twelve hours with 
baryta-water Cannizarro has obtained a salt from which hydro- 
chloric acid separates santonic acid (C 15 H 20 O 4 ). From a solution of 
calcium santonate the santonin is precipitated by acids. Boiled for 
some time with diluted sulphuric acid, it yields 87 per cent, of an 
insoluble resinous substance (santoniretin) and glucose (Kosmann). 
Santonin (Santoninum, U. S. P.) is official ; it is soluble in an aque- 
ous solution of twice its weight of sodium carbonate. Possibly 
(Berthelot) santonin resembles carbonic acid ; in other words, is a 
phenol, C 15 H 15 30H. Its glucosidic character is questionable. 

Process. — The process for its preparation consists in boiling san- 
fconica (Santonica, U. S. P.), the dried unexpanded flower-heads or 
capitula of Artemisia pauciflora with milk of lime (whereby cal- 
cium santonate is formed), straining, precipitating the santonin or 
santonic acid by hydrochloric acid, washing with ammonia to remove 
resin, dissolving in spirit, and digesting with animal charcoal to get 
rid of coloring-matter, setting the spirituous solution aside to de- 
posit crystals of santonin, and purifying by recrystallization from 
spirit (Mialhe). 

Test. — To highly-diluted solution of ferric chloride add an 
equal bulk of concentrated sulphuric acid. To this reagent 
add the santonin, or powder or substance suspected to be san- 
tonin, and cautiously apply heat. A red, purple, and finally 
violet, color is produced (Lindo). Santonin added to warm 
alcoholic solution of potash yields a violet-red color. 

Tanacetic Acid, from the leaves and tops of Tanacetum vidgare, or 
Tansy {Tanacetum, U. S. P.), is a yellow crystalline acid having the 
medicinal properties of santonin. 

Saponin (C 32 H 52 17 ,H 2 0) is a peculiar glucoside occurring in soap- 
wort, the root of the common pink, and many other plants ; its solu- 
tion in water, even though very dilute, froths like a solution of soap. 
Heated with dilute acids, it yields sugar and saponetin, C 40 H 66 O 15 , or 
saponegol, C 14 H 22 2 (Hesse). Pereira considered smilacin (salseparin 
or parallin) one of the principles of the supposed activity of the root 
of Smilax officinalis, or sarsaparilla (Sarsaparilla, U. S. P.), to be 

*The hydroxyacids losing water furnish, lactones. Aromatic com- 
pounds containing NH2 in the ortho position, and losing water by the oxi- 
dation and removal of one or two atoms of that hydrogen, furnish bodies 
which may be distinguished as lactams and lactims. 



508 ORGANIC CHEMISTRY. 

closely allied to, if not identical with, saponin. According to Klunge 
(" Pharmacographia"), parallin by action of acids yields parigenin. 
The aqueous solutions of parallin froth when shaken. Von Schultz 
states that sarsaparilla contains three homologous glucosides anal- 
ogous to saponin — namely, sarsaparill-saponin (C 20 H 32 O 10 ), ' sarsa- 
saponin (C 22 H 36 O 10 ), and parallin (C 26 H 44 O w ). 

Saponin is also met with in the root of Poly gala Senega (Senegce, 
U. S. P.), though the active principle of senega is said to reside in 
polygalic acid, probably a glucoside derivative of saponin. 

Saponin is readily obtained from the bark of Quillaja saponaria, 
or soap-bark {Quillaja, U. S. P.), by boiling the aqueous extract in 
alcohol and filtering while hot. Flocks of saponin separate on cool- 
ing. It is a white, non-crystalline, friable powder. 

The alleged toxic properties of commercial saponin are said by 
Kobert to be due to sapotoxin and quillaic acid. 

Scammonin (C 34 H 56 16 ). — Boil resin of scammony (Resina Scam- 
monii, U. S. P.) Avith diluted sulphuric acid for some time ; glu- 
cose may then be detected in the liquid, a resinous acid termed 
scammoniol (C u H 13 3 ?) being produced at the same time. 

Natural scammony (Scammonium, U. S. P.) is an exudation from 
incisions in the living root (Scammoniai Radix, B. P.) of Convol- 
vulus Scammonia. It contains from 10 to 20 per cent, of gum, and 
therefore, when rubbed up with water, gives an emulsion. "Ether 
removes about 75 per cent, of resin" (B. P.). The official resin of 
scammony contains no gum, and therefore gives no emulsion when 
rubbed up with water. It is made by digesting the root in spirit, 
adding water, distilling off the alcohol, and washing the residual 
resin with hot water till free from gum. There seems to be little or 
no chemical difference between the extracted resin and the resin of 
the exuded scammony. 

Resin of scammony is soluble in all proportions of ether. Spir- 
gatis states that it is identical with the resin of Mexican male 
jalap, which also is soluble in ether. Sulphuric acid slowly red- 
dens it. It is said to be liable to adulteration with resin of true 
jalap, guaiacum resin, and common rosin. Resin of true jalap is 
insoluble in ether; guaiacum resin is distinguished by the color- 
tests mentioned under Guaiacin, and rosin by the action of sul- 
phuric acid. 

Scillitin. — Schroff, and afterward Riche and Remont, believed 
the bitter principle of the squill-bulb (Scilla, B. P.) to be a glucoside. 
Merck has extracted substances which he has termed scillipicrin, 
scilliioxin, and scillin. Schmiedeberg has given the name of sines- 
trin to a squill principle. But no definite crystalline principle has 
yet been obtained. Squill contains a large quantity of mucilage. 

The bulbous root of Crinum Asiaticum is official in the Pharma- 
copoeia of India (Crini Radix, P. I.) as a substitute for squill. It 
has not been chemically investigated. 

Strophanthin (C 20 H 34 O 10 ; Arnaud, C 31 H 48 12 ). — According to 
Fraser, this is the active principle of strophanthus-seed (Strophan- 
thus hispidus, var. Kombe), and is a glucoside. He obtained it in. 
crystals. Acids convert it into glucose and crystalline strophan- 



IMPEEFECTLY EXAMINED SUBSTANCES. 



509 



thidin. Phosphomolybdic acid produces in solutions of strophan- 
thin a bright bluish-green color. Helbing states that its aqueous 
solution yields, with a trace of solution of ferric chloride and a little 
strong sulphuric acid, a reddish-brown precipitate which after an 
hour or two turns green. Sulphuric acid colors strophanthin dark 
green, changing to reddish brown. Recent researches indicate that 
strophanthin is only one of the active principles of the different 
species of Strophanthus. Strophanthus is official, Strophanthus, 
B. P. and U. S. P., yielding Tinctura Strophanthi, B. P. 



QUESTIONS AND EXERCISES. 

Define glucosides, and mention those of pharmaceutical interest. — 
Draw out an equation illustrative of the development of oil of bitter 
almonds. — How much pure amygdalin will yield 1 grain of real hydro- 
cyanic acid? — To what does cherry-laurel water owe its activity? — Men- 
tion the active principle of senna. — By what process is the glucoside 
of the purple foxglove prepared ? — State the circumstances under which 
guaiacum resin and jalap resin yield glucose. — Mention a test for guaiacum 
resin. — How may the adulteration of jalap resin by rosin be detected ? — 
Enumerate the tests for salicin. — How is santonin officially prepared? — 
Name the sources of saponin. — What is the difference between scammony 
and resin of scammony ? — How would you detect resins of turpentine, 
guaiacum, or jalap in resin of scammony? 



BITTER OR TONIC SUBSTANCES, Etc. 

The following articles, employed medicinally in such forms as 
decoction, extract, infusion, tincture, etc., contain active principles 
which have not yet been thoroughly examined. Some of these 
principles have been isolated, and a few have been obtained in the 
crystalline condition; but their constitution has not been sufficiently 
well made out to admit of the classification of the bodies either 
among alkaloids, glucosides, acids, or other well-marked principles: 



Andrographis Caules et Radix, 
P. I., from Andrographis pa- 
niculata, Kariyat. 

Anthemidis flores. 

Apocynum. Canadian hemp. 

Asclepias Tuberosa. Pleurisy- 
root (Asclepedin). 

Aurantii cortex. (Hesperidin.) 

Azadirachtce Cortex et Folia, P. I., 
from Azadirachta Indica, Nim 
or Margosa. (A resin, C 36 H 50 - 
O m Broughton.) 

Bonducellaz Semina, P. I., from 
Ccesalpina (Guilandina) Bon- 
ducella. Bonduc- 
Nickar-nuts. 



Buchu folia. 

Calendula officinalis. Marigold. 

(Calendulin, Stoltze.) 
Calotropis Cortex, P. I., from 

Calotropis procera and C. gi- 

gantea. Mudar. 
Canellos Cortex. (Cascarillin, 

Caulophyllum Thalictroides. 

Blue cohosh. Alkaloid? 

Cimicifuga (Actcea) racemosa. 
(Cimicifugin ; said by Conard 
to be neutral, and by Falck 
alkaloidal.) Black snake-root. 
(Cimicifugoz Bhizoma, B. P.) 



510 



ORGANIC CHEMISTRY. 



Cypripedium pubescens (Cypri- 
pedin?). Ladies' Slipper. 

Euonymus atropurpureus. Wa- 
hoo-bark. (Euonyinin ?) 

Euonymi Cortex, B. P., is " the 
dried root-bark," the source of 
Extractum Euonymi Siccum, 
B. P. 

Eupatorium perfoliatum. Thor- 
oughwort or Boneset. 

Gaulancha (Tinosporce Radix et 
Caules, P. I.). 

Gynocardice semina, from Gyno- 
cardia odorata. ( Chaulmugra, 
P. I.) 

Hamamelis Virginica. "Witch- 
hazel. 

The official portions are Hama- 
melidis Cortex, B. P., the source 
of Tinctura Hamamelidis, B. P., 
and Hamamelidis Folia, B. P., 
the source of Extractum Hama- 
melidis Liquidum, B. P. 

Hydrocotyles Folia, P. I., from 
Hydrocotyle Asiatica. Indian 
pennywort. 

Iris versicolor. Blue flag. (Iri- 
din or Irisin ?) 

Lactuca. (Lactucin, etc.) The 
milk-juice, dried, yields Lactu- 
carium. U. S. P. 



Lappa, U. S. P., Arctium Lappa, 
Lappa officinalis. Burdock. 

Lupulus. 

Magnolia. Swamp sassafras, or 
beaver tree. 

Marrubium. Horehound. Mar- 
rubein, a crystalline bitter sub- 
stance (Mein). 

Maticce Folia. Matico. 

Melia Azedarach. (Resin, Jacobs.) 

Pepo. The seed of Cucurbita 
Pepo. A remedy for tape- 
worm. 

Phytolacca Fructus et Radix. 
Poke fruit and root. Phyto- 
laccin, a crystalline substance 
(Claassen). 

Scutellaria. Skullcap. 

Serpentaria. Virginia Snakeroot. 

Soymidce Cortex, P. I. Rohun- 
bark, from Soymida febrifuga. 

Taraxaci Radix. (Taraxacin.) 

Todclalice Radix, P. I. 

Triticum repens. Rhizome of 
couch-grass. 

Veronica Virginica, 
rhizome. Culvers 
tandra, U. S. P. 
drin ?) 

Viburnum prunij 
haw. ( Viburnin.) 



roots and 

root ; Lep- 

(Leptan- 



Black 



ALKALOIDS. 

Constitution of Alkaloids, or Organic Bases. 

Natural Alkaloids. — The natural organic bases, alkaloids, or 
alkali-like bodies (eldog, eidos, likeness), have many analogies with 
ammonia. Their constitution as a class is not yet satisfactorily 
known, but some are possibly direct derivatives of a single molecule 
of ammonia (NH) 3 or of double, triple, or quadruple molecules 
(N 2 H 6 , N 3 H 9 , N 4 H 12 ) ; others of ammonias in which the ammoniacal 
structure is largely merged in or conditioned by a benzenoid or 
aromatic structure, or, vice versa, in which the benzenoid character 
is conditioned by the ammoniacal ; while others again certainly 
appear to be benzenoid, but of a more or less nitrogen-benzene 
(pyridinoid) rather than a completely carbon-benzene character — 
benzene in which CH /// is displaced by 1S T/// (p. 513). 

Numerous artificial organic bases, having a simple ammoniacal 
constitution, have already been formed. These are sometimes 
termed amido, imido, and nitrite bases, or amines, and are primary, 



ALKALOIDS. 511 

secondary, and tertiary according as one, two, or three atoms of 
hydrogen in ammonia have been displaced by radicals, as seen in 
the following general formulae (R = any univalent radical) : 

R) III R 



H V N EN R y N 

Hj HJ R 

or in the following examples : 

C 2 H 5 1 ^2-^5 

H I N C 2 H 5 y 

Ethylamine, or Diethylaniine, or Triethylamine, or 
ethylia (C 2 H 7 N). diethylia (C^H^N). triethylia (C 6 H 15 N). 

The three classes have also been termed amidogen bases (NH 2 ), 
imidogen bases (NH), and nitrile bases (N). 

Formation of Some of the Artificial Organic Bases. — A few illus- 
trations will suffice : Just as the addition of hydrogen iodide (HI) to 
ammonia (that is, the common trihydrogen ammonia, NH 3 ) gives 
common ammonium iodide (NHHHHI or NH 4 I), so the addition of 
ethyl iodide (C 2 H 5 I or EtI) (see p. 402) to ammonia (NH 3 ) gives 
ethyl-ammonium iodide (NHHHEtl, or NH 3 EtI, or NH 3 C 2 H 5 I). A 
fixed alkali turns out common ammonia (NHHH) from the iodide 
(or any other salt) of common ammonium ; it turns out ethyl- 
ammonia (NHHEt) from the iodide (or any other salt) of ethyl- 
ammonium. Ethyl-ammonia (or ethylia, or ethylamine), NHHEt, 
with ethyl iodide, EtI, gives diethyl-ammonium iodide [NHHEtEtl, 
or NH 2 Et 2 I, or NH 2 (C 2 H 5 ) 2 I]. From the latter potash turns out 
diethyl-ammonia (NHEt 2 ). Diethyl-ammonia (diethylia or diethyl- 
amine) with ethyl iodide gives triethyl-ammonium iodide (NHEt 3 I). 
The latter with alkali gives triethyl-ammonia, or triethylia, or tri- 
ethylamine (NEt 3 ), and this with ethyl-iodide gives tetrethyl ammo- 
nium iodide, NEt 4 I, or N(C 2 H 5 ) 4 I. 

What has just been stated respecting ethyl iodide is true of other 
ethyl salts ; and what is true of ethyl salts is true of salts of an 
immense number of other radicals — univalent, bivalent, etc. ; so 
that a vast number of artificial organic bases and their salts can be 
produced. The reactions are not always so sharp as those just given. 
Mixtures of primary, secondary, and tertiary compounds, rather 
than either alone, often occur in an experiment, but the reactions 
are typically true. Some of these artificial bases not only resemble 
natural alkaloids, but are strong caustic liquids, like solution of 
ammonia. 

Then the displacing radical in an artificial alkaloid or its salt may 
not only be of one kind, as indicated in the preceding paragraphs, 
but of different kinds ; and while the radical displacing one atom of 
hydrogen is keeping its place, any of the many known radicals may 
occupy the position of one or all of the other atoms of hydrogen. 
Thus, for example, we have methyl-ethyl-amylamine (C 8 H 19 N, or 
NCH 3 C 2 H 5 C 5 H n , or NMeEtAy), a colorless, oily body of agreeable 
aromatic odor. The empirical formulae of the vegeto-alkaloids mor- 



512 ORGANIC CHEMISTRY. 

phine, quinine, etc. may some day be similarly resolvable into 
rational formulae, either simply ammoniacal, benzenoid, or pyridi- 
noid. Their artificial production will then quickly follow. In a few 
cases this has already been accomplished. 

Analogues of Amines. — From the analogy of phosphorus, arsenum, 
and antimony to nitrogen there exist, as might be expected, phos- 
phines, arsiyies, and stibines, bases resembling amines, but contain- 
ing the respective elements (P, As, Sb) in place of the nitrogen (N) 
of the amines. 

Methylamine (CH 3 HHN) and trimethylamine (CH 3 ) 3 N are artificial 
ammoniacal alkaloids. The former was found by Schmidt in Mer- 
curiaiis annua and M. perennis, and previously by Reichardt, who 
termed it mercurialine. Trimethylamine is also produced in large 
quantities in the dry distillation of the evaporated residue of the 
spent wash produced in beet-root spirit distilleries. 

Propylamine, or tritylia (C 3 H 7 HHN), is a volatile oil, one prod- 
uct of the destructive distillation of bones and other animal 
matters. 

The organic bases derived from one molecule of ammonia are 
termed monamines ; from two molecules, diamines ; from three, tri- 
amines ; and from four, tetramines : 



R) 


*M 


R 3 ) 


*M 


rI n 


MN 2 


r 3 In 3 


M N ± 


Rj 


bJ 


R 3 J 


bJ 



In these amines any bivalent, trivalent, or quadrivalent radical 
may occupy the place of two, three, or four univalent radicals (R). 
The diethylene-diamine is used medicinally under the name piper- 
azine ; its constitution is that of piperidine {vide Index), in which 
NH displaces CH 2 . 

Wurtz first obtained methylamine and ethylamine in 1849 : Hof- 
mann, in 1850 and subsequently, added enormously to our know- 
ledge of the secondary, tertiary, and other amines and of the directly 
ammoniacal type of bodies generally. Kekule linked on the 
aromatic or benzene type in 1865. Dewar and Korner almost 
simultaneously, in 1870, demonstrated the benzenoid character of 
pyridine and quinoline (see p. 514), while no one has since been 
more active in alkaloidal research than Ladenburg. 

Vegetal Alkaloids. — These are of great importance to the medical 
and pharmaceutical student. They are treated in considerable 
detail in the succeeding pages. 

Animal Alkaloids. — Many well-known alkaloids occur in the juice 
of the flesh and in other parts of animals. Ordinary extract of 
meat contains abundance of crystals of creatine, C 4 H 9 N 3 2 , and 
some creatinine, C 4 H 7 N 3 0. Creatine easily parts with the elements 
of water and yields creatinine ; it takes up the elements of water and 
yields sarkosine, C 3 H 7 N0 2 , and urea, CH 4 N 2 0. Sarkosine is methyl- 
glycocoll. Taurine, C 2 H 7 NS0 3 , may be obtained from bile, and it 
can be constructed artificially from its elements. Some animal 
tissues, as of the spleen, brain, and pancreas, yield, as a product of 



ALKALOIDS. 513 

work, leucine, C 6 H 13 N0 2 , which occurs in white, pearly crystals ; 
also tyrosine, C 9 H n N0 3 . Gautier recently obtained several new 
alkaloids from albumenoids, and hence termed them leucoma'ines 
{levnojia, leucoma, white of egg) — namely, xanthocreatinine, C 5 H ]0 N 4 O, 
crusocreatinine, C 5 H 8 N 4 0, amphicreatinine, C 9 H 19 N 7 4 , and pseudo- 
xanthine, C 4 H 5 N 5 0. The leucoma'ines and the animal alkaloids gen- 
erally are of great physiological interest. Some of the leucomames 
are toxic and indistinguishable from ptomaines ; in fact, the three 
classes merge into one another. 

Ptomaines. — A series of diamines, many of them toxic, have been 
isolated by Brieger from decaying nitrogenous animal principles, 
including the putrid albumenoids or proteids of the human body 
itself — hence the name ptomaines (nTufia, ptoma, sl corpse.) These 
have some medico-legal importance, but, inasmuch as they may 
occur in life, poisoning the blood during the progress of disease, 
especially disease associated with the development of micro-organ- 
isms or microbes— that is, zymotic disease (£17/77, zume, ferment) — 
they have great pathological interest ; indeed, physiological interest 
also, for one of a curaroid character seems to play a part in the 
process of digestion. The names of some of these bases are — neurine 
(C 5 H 13 NO) and neuridene (C 5 H U N 2 ), from putrid flesh ; muscarine 
(C 5 H 13 N0 2 ) and gadinine (C 7 H 16 N0 2 ), from putrid fish ; cadaverine 
(C 5 H 16 N 2 ), saprine, and putrescine, (C 4 H ]2 N 2 ), from putrid human re- 
mains, choline being met with in the earlier stages of decay ; and 
tetanine (C 13 H 30 N 2 OJ, the administration of which to animals pro- 
duced symptoms resembling those of tetanus in man, from beef 
putrified by the agency of the microbe which is associated with the 
cause of traumatic tetanus so distressing to the human subject. 
Tyrotoxicon was the name given by Vaughan to a toxic ptomaine he 
isolated from poisonous cheese (r<vpbc, twos, cheese ; rotjindv, toxicon, 
poison), afterward from poisonous milk and cream, which, taken as 
food, had caused more or less vomiting, headache, and diarrhoea. He 
afterward recognized it as diazobenzene hydrate, C 6 H 5 *N : NOH. 
Brieger states that when shell-fish is poisonous it is due to the 
presence of a ptomaine he has named mytiloxine, C 6 H 15 N0 2 . Para- 
and meta-phenylene-diamine appear to have all the characters of 
leucoma'ines or ptomaines, the latter causing intense influenza. 

Evidence of Constitution of the Natural Alkaloids. — Attempts to 
form artificially the more important natural organic bases com- 
monly used in medicine have hitherto failed. Many artificial colori- 
fic alkaloids of the amidobenzene (aniline or phenylamine) type, and 
of a curious double nitrogen type (azo- or, rather, diazo-type ; see 
the non-colorific diazobenzene, as above), have been obtained. But 
the type of the natural medicinal alkaloids seems rather to be found 
in pyridine, C 5 H 5 N. Pyridine is producible in various ways, but is 
contained in bone oil (from the distillation of bones — whence, also, 
pyrrol, C 4 H 5 N, and thence iodopyrrol, or ioclol, C 4 I 4 HN, a rival 
of iodoform), together with the homologues picoline, C 6 H 7 N (or 
methylpyridine, ortho-, meta-, or para-) ; lutidine, C 7 H 9 N ; and 
collidine, C 8 H n N, forming an homologous series of pyridine bases, 

C n H 2n _ 5 N. 



514 



ORGANIC CHEMISTRY. 







H 








C 


N 






^\ 


J\ 




(C 6 H 5 


HC CNK, 


HC CH 


N 


H or 


1 II 


1 II 




i H 


HC CH 


HC CH 






V 


V 






c 


C 






H 


H 


Phe 


nylainine or 


anaido-benzene. 


Pyridine. 



From quinine, cinchonine, and strychnine, by the disruptive 
action of caustic alkalies, not only pyridine and homologues, but 
quinoline or chinoline, C 9 H 7 N, have been obtained ; hence pyridine 
and quinoline would seem to contribute to the construction of those 
and similar alkaloids. Quinoline can be made in various other 
ways, especially (Skraup) from nitrobenzene, aniline, and glycerin. 
Quinoline is closely related both to benzene and to pyridine (see the 
following formula). Its relation to naphthalene (two carbon-con- 
joined benzene residues) is the relation of pyridine to benzene. 



H H 

hcA/\ h 

i ii r 

HC C CH 

c c 

H H 

Naphthalene. 



H 

C N 

HC A C A CH 

I II I 
HC C CH 

\/\/- 

a a C C 

Alpha and beta positions. JJ JJ 

Quinoline. 



Both pyridine and quinoline form additive compounds with 
hydrogen. (See Piperidine in Index.) 

By adding six atoms of hydrogen to pyridine, piperidine is ob- 
tained, and conine, the alkaloid of hemlock, is piperidine with 
propyl (C 3 H 7 ) replacing one of the hydrogen atoms. It has been 
formed artificially by Landenburg from picoline. (See also Ecgonine, 
Tropine, etc.) 

Chemists, in the hope, doubtless, of discovering how to produce the 
valuable medicinal alkaloids artificially, have obtained several alka- 
loidal derivatives of quinoline. One, Jcairine, somewhat resembles 
quinine. 

Again, alkaloids yield organic acids, and organic acids — notably 
those occurring in the nicotine-yielding and morphine-yielding 
plants — may be converted into pyridine compounds when the con- 
stituents of their molecules are interwoven with those of ammonia. 

A careful consideration of the above and allied facts irresistibly 
leads to the inference that we are at last almost " within measurable 
distance " of the artificial production of most of the natural alka- 
loids. This is a subject of financial and general commercial weight •, 
of considerable technological, including pharmaceutical, importance ; 
of very great medical consequence, especially taken in connection 



ALKALOIDS. 515 

with its ramifications ; and of transcendent interest as illustrating 
the working of the forces of nature within the molecules of matter. 

Vegeto-animal Alkaloids. — Choline, C 5 H 15 N0 2 , occurs in the bile 
and the brain, also in ergot and ipecacuanha, hops, areca-nut, cotton- 
seed cake, Scopola Japonica, etc. Guanine, C 5 H 5 N 5 0, and Sarkine, 
C 5 H 4 N 4 0, are found in flesh and in young plane-leaves. Fresh meat 
furnishes Carnine, C 7 H 8 N 4 3 ; and Betaine, C 5 H n N0 2 , is found in 
beet-root, cotton-seed cake, and in urine. 

Hydroxylamine. — Besid s the amide, imide, and nitrile bases 
already mentioned, ammonia may have one atom of its hydrogen dis- 
placed by hydroxyl, hydroxylamine (NH 2 OH) resulting. It is often 
formed when nascent hydrogen acts on an oxide of nitrogen, as 
when zinc, diluted sulphuric acid, and a little nitric acid are brought 
together. It yields substitution-products, as ethylhydroxylamine 
(NHC 2 H 5 OH), and additive compounds, as hydroxylamine hydro- 
chlorate (NH 2 OH,HCl) : 



( H 


f H 


fC 2 H 5 


f H 


N^H 


N^H 


N^H 


HNH HC1 


(h 


(OH 


(OH 


(oh 


Ammonia. 


Hydroxyl- 


Ethyl- 


Hydroxylamine 
hydrochlorate. 




amine. 


hydroxylamine. 



Hydroxylamine and aldehydes yield aldoximes. Hydroxylamine 
and acetones yield acetoximes. {Vide manuals not limited to the 
requirements of medical and pharmaceutical students.) 

Hydrazine, H 2 N — NH 2 . — Diethylamine, by action of nitrous acid, 
yields a nitroso-derivative which, on reduction, furnishes what ap- 
parently is a diamidic compound — diethylhydrazine (C 2 H 5 ) 2 N— NH 2 . 
Hydrous hydrazine has the formula H 2 N — NH 2 ,H 2 0. Hydrazine 
itself cannot very easily be isolated. Its salts with ordinary acids 
are generally crystalline and isomorphous with corresponding 
ammonium salts. Acidified, they have very powerful reducing 
properties, and act as strong poisons toward the lower organisms. 

Azoimide or Imidazoic Acid, HN 3 , is a body closely resembling 
the haloid acids, and was originally prepared by Curtius from hydra- 
zine and ethyl hippurate ; it may, however, be prepared more easily 
by a method proposed by Wislicenus, in which sodamide, NaNH 2 , 
prepared by passing NH 3 over melted sodium, is heated with nitrous 
oxide. 

Note on Nomenclature of Natural Alkaloids. — The first syllables 
of the names of the natural alkaloids recall the name of the plant 
whence they were obtained or some characteristic property. It is 
to be regretted that the last syllable is not either ine or ia, instead 
of sometimes one and sometimes the other. The termination in ia 
distinguishes the alkaloids from some other substances the names 
of which end in ine, as aniline, bromine, chlorine, fluorine, iodine, 
morphine, etc., but traders generally and the compilers of the Ameri- 
can, British, French, and German Pharmacopoeias adopt the ter- 
mination in ine. The names of the salts of the alkaloids are given 
on the assumption that the acid unites with the alkaloid without 
decomposition. Thus hydrochlorate (sometimes termed "hydro- 



516 ORGANIC CHEMISTRY. 

chloride ") of morphine is regarded as morphine with added hydro- 
chloric acid ; as we might assume sal-ammoniac to be ammonia 
(NH 3 ) with hydrochloric acid (HC1), and name it hydrochlorate of 
ammonia (NH 3 HC1) instead of ammonium chloride (NH 4 C1). All 
acids, even sulphydric, unite with alkaloids and form additive salts 
having similar names. 

Antidotes. — In cases of poisoning by alkaloids, emetics and the 
stomach-pump must be relied on rather than chemical agents. But 
astringent liquids may be administered, for tannic acid precipitates 
many of the alkaloids from their aqueous solution, absorption of the 
poison being thus possibly retarded. 



MORPHINE AND OTHER OPIUM ALKALOIDS. 

Formula of Morphine, C 17 H 19 N0 8 ,H 2 0. Molecular weight, 303. 

Occurrence. — Morphine, or morphia, occurs in opium (the inspis- 
sated juice of the fruit, termed the capsule, of the white poppy, 
Papaver somniferum) as morphine meconate [(C :7 H 19 N0 3 ) 2 ,C 7 H 4 7 ,- 
5H 2 0, Dott] and sulphate. The dried poppy-capsule of pharmacy 
(Papaveris Capsules, B. P.) contains opium principles, but varying 
much in nature and proportion : the presence of morphine, narcotine, 
and meconic acid has been demonstrated, and, by Groves, of codeine 
and narceine. Ordinary moist opium (Opiwn, U. S. P.) should con- 
tain not "less than 9 per cent, of crystalline morphine," and, when 
dried at 85° C. and powdered (Opii Pulvis, U. S. P.), not less than 
13 nor more than 15 per cent, of crystallized morphine. 

Deodorized Opium ( Opium Deodoratum, U. S. P.), the old denar- 
cotized opium, is dried and powdered opium from which narcotine 
has been washed out by fourteen times its weight of ether, the prod- 
uct being redried at 85° C. and made up to its original weight with 
powdered sugar of milk. 

Morphina, U. S. P., may be made by adding to infusion of opium 
an equal bulk of alcohol, then slight excess of ammonia, and setting 
aside for crystalline morphine to separate. It is purified by recrys- 
tallization in colorless, shining, prismatic crystals. 

Process for Hydrochlorate. — : The hydrochlorate, C 17 H 19 N0 3 ,- 
HC1,3H 2 (Morphinm Hydrochloras, U. S. P.), occurs in slen- 
der white acicular crystals ; it is prepared by simply decom- 
posing an aqueous infusion of opium with calcium chloride, 
dalcium meconate and morphine hydrochlorate being produced. 
(If the infusion, which is always acid, be first nearly neutral- 
ized by the cautious addition of small quantities of a very 
dilute solution of ammonia, the calcium chloride then at once 
causes a precipitate of calcium meconate, which can be filtered 
off, leaving a colored solution of morphine hydrochlorate. On 
the large scale — vide B. P. — the details are somewhat different.) 
The salt is partially purified by crystallization from the evap- 



ALKALOIDS. 517 

orated liquid, then by treatment of the solution of the impure 
hydrochlorate by animal charcoal, and lastly by precipitation 
of the morphine from the still colored liquid by ammonia and 
re-solution of the morphine in hot dilute hydrochloric acid ; 
morphine hydrochlorate separates out on cooling. 

Morphine hydrochlorate deposited from a hot solution in about 
twenty times its weight of alcohol is anhydrous. 

Morphine may also, of course, be prepared by the methods given 
for the assay of opium. (See Index.) 

Process for Acetate. — Morphine acetate (C 17 H 19 N0 3 ,C 2 H 4 2 ,3H 2 0) 
{Morphince Acetas, U. S. P.), a white pulverulent salt, is prepared 
by dissolving morphine in acetic acid, the morphine being obtained 
from a solution of the hydrochlorate by precipitation with ammonia 
or direct from opium. 15 parts of hydrochlorate yield, theoretically, 
16 of acetate. 1 grain of acetate in 10 minims of water forms the 
Injectio Morphince Hypodermica, B. P. 

Both morphine hydrochlorate and acetate are soluble in water, 
but the solution is not stable unless acidulated and containing alco- 
hol ; hence the official solutions, 1 per cent. {Liquor Morphince 
Hydrochloratis, B. P., and Liquor Morphince Acetatis, B. P.), consist 
of 3 parts of water and 1 part rectified spirit, a few minims per 
ounce of hydrochloric or acetic acid being added. Even solid mor- 
phine acetate is unstable, slowly dissociating into acetic acid and 
morphine ; hence the acid odor of morphine acetate ; hence, too, the 
necessity, when a solution of morphine acetate of perfectly definite 
strength is required, of preparing it from a weighed quantity of 
hydrochlorate or of pure crystalline morphine. Other preparations 
official in the British Pharmacopoeia are — Suppositoria Morphince, 
Trochlsci Morphince, Trochisci Morphince et Ipecacuanhce, and Liquor 
Morphince Bimeconatis. The latter is made by dissolving morphine 
in a diluted spirituous solution of meconic acid. It contains about 
li p er cent, of the so-called morphine bimeconate (C 17 H 19 N0 3 C 7 - 
H 4 7 ?), and, so far, resembles tincture of opium. 

Process for Sulphate. — Morphine sulphate (C 17 H 19 N0 3 ) 2 H 2 S0 4 ,- 
5H 2 0) {Morphince Sulphas, U. S. P.) is prepared by neutralizing 
precipitated morphine with diluted sulphuric acid. It occurs in 
white silky crystals, not very soluble in water. A 1 per cent, solu- 
tion in weak spirit forms the Liquor Morphince Sulphatis, B. P. It 
is a constituent of Pulvis Morphince Compositus, U. S. P. 

Solubility of Morphine Salts in Water at 60° F. — According to 
Dott, 1 part of the respective salts is soluble in the annexed num- 
bers of parts of water : acetate, 2\ ; tartrate, 9f ; sulphate, 23 ; 
hydrochlorate, 24 ; meconate, 34. 

Morphine Tartrate has the formula (C 17 H 19 N0 3 ) 2 ,C 4 H 6 6 ,3H 2 0. 

Codeine, or Codeia (C re H 21 N0 3 ,H 2 0). is another officially recog- 
nized alkaloid of opium {Codeina, U. S. P.). It is soluble in the 
slight excess of ammonia employed in the foregoing process for the 
separation of morphine. It is obtained by evaporating the ammo- 
niacal liquors, " treating the residue with water, precipitating with 
caustic potash, and purifving the precipitated alkaloid by recrystal- 
23 



518 ORGANIC CHEMISTRY. 

lization from ether. It occurs in colorless or nearly colorless octa- 
hedral crystals ; soluble in 80 parts of water and of solution of 
ammonia, readily soluble in spirit and in diluted acids. The aque- 
ous solution has a bitter taste and an alkaline reaction. The alka- 
loid dissolves in sulphuric acid, forming a colorless solution, which, 
when gently warmed with ammonium molybdate or a trace of ferric 
chloride, assumes a deep-blue color. Ignited in air, it yields no 
ash." — B. P. The U. S. P. also requires codeine to be neutral to 
litmus-paper, and it should dissolve in nitric acid of sp. gr. 1.200 to a 
yellow liquid which should not become red (difference from and 
absence of morphine). It reduces a solution of 1 part of ammonium 
selenite in 20 of strong sulphuric acid, yielding a green color (Lafon). 
(See also p. 520.) 

Other alkaloids exist in opium. In the above process for mor- 
phine a considerable quantity of an alkaloid of very weak basic 
properties, narcotine, (C 22 H 23 N0 7 ) or C 19 H u (CH 3 ) ? N0 7 (Narcotina, 
P. I.), remains in the exhausted opium, and may be extracted by 
digesting in acetic acid, filtering, and precipitating by ammonia. 
It crystallizes in brilliant needles from alcohol or ether. The 
formula of its hydrochlorate is C 22 H 23 N0 7 ,HC1,H 2 0. By oxidation 
it yields cotarnine and an acid termed opianic. From the mother- 
liquors there have also been obtained thebaine (C 19 H 21 N0 3 ), papav- 
erine (C 21 H 21 N0 4 , Hesse; C 20 H 21 NO 4 , Merck), opianine (C 21 H 21 N0 7 ?), 
narceine (C 23 H 29 N0 9 ), cryptopine (C 21 H 23 N0 5 ), meconin (C 10 H 10 O 4 ), 
meconoisin (C 8 H 10 O 2 ), laudanine (C 20 H 25 NO 4 ), codamine (C 20 H 25 NO 4 ), 
gnoscopine (C 34 H 36 N 2 O n ), pseudomorphine (C 17 H 18 N0 3 ), proiopine 
(C 20 H 19 NO 5 ), laudanosine (C 21 H 27 N0 4 ), liydrocotarnine (C 20 H 19 NO 5 ), 
rhceadine (C 23 H 21 N0 6 ), meconidine (C 21 H 23 N0 4 ), lanthopine (C 23 H 25 - 
N0 4 ). 

A little acetic acid also exists in all opium (D. Brown). 

Analytical Reactions. 

First Analytical Reaction. — To a minute fragment of a mor- 
phine salt add 1 drop of water, and warm the mixture until 
the salt dissolves ; then stir the liquid with a glass rod moist- 
ened by a strong neutral solution of ferric chloride ; a dirty- 
blue color is produced. 

Even in dilute solutions morphine reduces potassium ferri- 
cyanide to ferrocyanide, hence may be detected by the blue 
precipitate (prussian blue) produced on the addition of ferric 
chloride and ferricyanide. Other substances, but no other offi- 
cial alkaloids, give this reaction. 

Second Analytical Reaction. — To a -drop or two of a strong 
solution of a morphine salt in a test-tube add a minute frag- 
ment of iodic acid (HI0 3 , p. 296) ;. iodine is set free. Into the 
upper part of the tube insert a glass rod covered with starch 
mucilage, and warm the solution ; dark-blue ■" starch iodide " 
is produced. If the mixture of morphine and iodic acid be 



ALKALOIDS. 519 

shaken up with chloroform or carbon disulphide, a violet solu- 
tion is obtained. This reaction is only confirmatory of others, 
as albuminous matters also reduce iodic acid. 

Third Analytical Reaction. — To a few drops of an aqueous 
infusion of opium add a drop of neutral solution of ferric 
chloride ; a red solution of the ferric meconate is produced. 
Add solution of corrosive sublimate ; the color is not destroyed 
(as it is in the case of ferric sulphocyanate, a salt of similar 
tint). In cases of poisoning by a preparation of opium this 
test is almost as conclusive as a direct reaction of morphine 
(the poison itself), meconic acid being obtainable from opium 
only. 

Other Reactions. — Add sodium carbonate to a solution of a 
salt of morphine ; a white precipitate of morphine falls, slowly 
and of a crystalline character if the solution is dilute. Collect 
this precipitate and moisten it with neutral solution of ferric 

chloride ; the bluish tint above referred to is produced. 

Add an alkali to a solution of hydrochlorate or acetate of the 
alkaloid ; morphine is precipitated, soluble in excess of the 
fixed alkali, far less readily so in ammonia. Moisten a par- 
ticle of a morphine salt with nitric acid ; an orange-red colora- 
tion is produced. Warm a little morphine with strong sul- 
phuric acid and sodium arsenate ; blue-green tinges result. 

To morphine add strong sulphuric acid, mix, and strew bis- 
muth nitrate on the fluid ; the mixture turns dark brown or 

black. Heat morphine on platinum-foil ; it burns entirely 

away. 

Apomorphine (C 17 H 17 N0 2 ). 

Apomorphine (arrb, apo, from, and morphine) is an alkaloid 
obtained from morphine by Matthiessen and Wright. It possesses 
remarkable physiological effects : one-tenth of a grain (in aqueous 
solution) injected under the skin, or a quarter of a grain taken into 
the stomach, produces vomiting in from four to ten minutes. 

Process. — -Morphine hydrochlorate is hermetically sealed in a 
thick tube with considerable excess of hydrochloric acid, and heated 
to nearly 300° F. for two or three hours. The product is purified 
by diluting the contents of the tube with water, precipitating with 
sodium bicarbonate, and treating the precipitate with ether or chlo- 
roform. On shaking up the ethereal or chloroform solution with 

a very small quantity of strong hydrochloric acid, the sides of the 
vessel become covered with crystals of the hydrochlorate of the new 
base. These may be drained from the mother-liquor, washed with 
a little cold water, in which the salt is sparingly soluble, recrystal- 
lized from hot water, and dried on bibulous paper or over sulphuric 
acid. The formula (C 1Y H 17 N0 2 HC1) indicates that the new alkaloid 
is derived from morphine by abstraction of the elements of water. 

Apomorphine Hydrochlorate {Apomorphinoz Hydrochloras, U. S. 



520 OEGANIC CHEMISTRY. 

P.) occurs in colorless or grayish -white shining crystals, turning 
greenish on exposure to light and air, odorless, having a bitter taste 
and a neutral or faintly acid reaction. Soluble in 45 parts of water 
and in 45 parts of alcohol at 15° C. (59° F.). "When heated to 
near 100° C. (212° F.) the salt is decomposed, rapidly if in solution, 
slowly when dry. At 270° C. (518° F.) it fuses to a black mass, 
and when ignited it is consumed without leaving a residue. Nitric 
acid colors the crystals blood-red to orange ; sulphuric acid, violet 
to light-brown ; dark-purple by a mixture of the two acids. A few 
crystals of manganese dioxide will color a saturated solution of 
apomorphine hydrochlorate green, which will be turned by a crystal 
of oxalic acid to a reddish-brown. "Addition of sodium-bicarbonate 
solution to the aqueous solution throws down the white amorphous 
alkaloid, which soon turns green on exposure to air, and imparts a 
violet or blue color to chloroform, in which it is very soluble (differ- 
ence from morphine). If the salt impart at once an emerald-green 
color to 100 parts of water on being shaken with it a few times in 
a test-tube, it should be rejected." — U. S. P. 2 grains of the hydro- 
chlorate dissolved in 100 minims of camphor-water constitute the 
Injectio ApomorphincE Hypodermica, B. P. 

Codeine also, according to the same chemists, yields apomorphine 
by similar treatment, a reaction that would seem to indicate that 
codeine is methyl-morphine ; indeed, Grimaux (Hesse also) has 
since obtained codeine — or, possibly, an isomer of codeine, methyl- 
morphine — from morphine. Codeine may also be obtained by heat- 
ing a sodium compound of morphine, C n H 18 NaN0 3 , with methyl 
iodide, CH 3 I • sodium iodide and methyl-morphine or codeine result. 

Codeine gives neither a blue color with ferric chloride nor a red 
with nitric acid. Both codeine and morphine when heated with a 
mixture of strong sulphuric acid and sodium arsenate give a blue 
color, the morphine yielding a greenish blue and the codeine a 
violet blue. 

Constitution of the Opium Alkaloids. — The opium alkaloids, like 
the cinchona alkaloids, have been attacked by many highly-skilled 
chemists in the hope that analytical — or, in a sense, destructive — 
investigation would lead to synthetical or constructive knowledge, 
and many interesting and promising results have been obtained. 
But the subject is not yet sufficiently advanced for presentation 
before the younger students of medicine or pharmacy. 



QUESTIONS AND EXEECISES. 



Write some general formulae of artificial alkaloids. — Name the sub- 
stances represented by the following formulae : 

C 3 H 7 ) C3H7) CH 3 ) CH 3 ) CH 3 ) CH 3 ) 

H \ N, C3H7 I N, C2H5 [ N, H N, CH 3 [ N, CH 3 Y N. 
H J H J C5H11J H J H J CH 5 J 

What is the assumed constitution of the salts of the alkaloids ? — Describe 
the treatment in cases of poisoning by alkaloids. — Give the official 
process for the preparation of morphine hydrochlorate. In what form 



ALKALOIDS. 521 

does morphine occur in opium ? — How is morphine acetate prepared ? — 
What plan is adopted for preventing the decomposition of the official 
solutions of morphine ? — Mention the analytical reactions of morphine. — 
In addition to the reactions of morphine, what test may be employed in 
searching for opium in a liquid or semi-fluid material? — How is apomor- 
phine prepared ? and what are its properties ? — Describe the relation of 
morphine to codeine. 

QUININE AND OTHER CINCHONA ALKALOIDS. 

Formula of Quinine, C 20 H 24 N 2 O 2 ,3H 2 O. Molecular weight, 378. 

Source. — Quinine (Quinina, U. S. P.) and other alkaloids exist in 
the varieties of cinchona-bark as kinates, or, rather, quinates* In 
the British Pharmacopoeia cinchona-bark is defined as "the dried 
bark of Cinchona Calisaya, Weddell ; Cinchona officinalis, Linn. ; 
Cinchona succirubra, Pavon ; Cinchona lancifolia, Ahitis ; and other 
species of Cinchona from which the peculiar alkaloids of the bark 
may be obtained." The official galenical preparations are made 
with the succirubra or red cinchona-bark {Cinchona Rubra, U. S. P.). 
Quinine, quinidine, and cinchonine also occur, together with cupre- 
ine, in the bark of various species of Remijia, known as cuprea- 
bark. 

Under Cinchona the United States Pharmacopoeia recognizes " the 
bark of any species of Cinchona containing at least 5 per cent, of 
its peculiar alkaloids." 

Extraction of the Mixed Alkaloids. — Mix about 2 ounces of 
powdered bark with a quarter of its weight of lime and a little 
water, and extract with benzoated amylic alcohol. .(For a 
description of this operation see " Quinine, Quantitative Esti- 
mation of," in the Index.) Shake the product in a separating- 
funnel, with an ounce of water acidulated with sulphuric or 
hydrochloric acid. Draw off the aqueous liquid, which will 
contain the alkaloids as acid salts, and add to it a slight excess 
of ammonia. Collect the precipitated alkaloids on a filter, 
wash, and dry in the air or over a dish of sulphuric acid cov- 
ered by a bell-glass. (For the separation of alkaloids see 
Index, "De Vrij's Process" — an operation which should not 
be attempted at this stage of study.) 

Process for Quinine Sulphate.— Quinine sulphate (Quinince Sid- 
phas, U. S. P.) may be prepared by treating the yellow bark with 
diluted hydrochloric acid, precipitating # the resulting solution of 
quinine hydrochlorate by soda, and redissolving the precipitated 
quinine in the proper proportion of hot diluted sulphuric acid ; or 

* Quinic acid, C7H12O6, occurs in cinchona, coffee, holly, ivy, oak, elm, 
etc. Heated, it yields hydroqninone, C6H4(OH>2. Oxidized, it gives 
quinone, C6H4O2, which is probably a di-ketone, C4Ht(CO)2, dicarbonyl 

benzene, or C 2 H2<CSq>C2H2. The homologues of benzene yield other 

" quinones." 



522 ORGANIC CHEMISTRY. 

by extracting with spirit, etc. after the addition of lime. (See the 
sections on the quantitative analysis of cinchona-bark.) This, the 
common commercial sulphate, crystallizes out on cooling in silky 
acicular crystals, one molecule containing two atoms of quinine 
(2C 20 H 24 N 2 O 2 ), one of sulphuric acid (H 2 SOJ, and eight of water of 
crystallization (8H 2 0). 

In the process of an old United States Pharmacopoeia (1870) lime 
was used instead of soda, the precipitated quinine dissolved in boiling 
alcohol, the latter recovered by distillation, the residual quinine 
neutralized by diluted sulphuric acid, the solution treated with 
animal charcoal, filtered while hot, set aside to crystallize, and re- 
crystallized if necessary. 

Quinine sulphate, the common or so-called disulphate — (C 20 H 24 N 2 - 
2 ) 2 ,H 2 S0 4 ,8H 2 0) — is only slightly soluble in water •, on the addition 
of diluted sulphuric acid the so-called neutral sulphate or soluble 
sulphate (Quinince Bisulphas, U. S. P.) (C 20 H 24 N 2 O 2 ,H 2 SO 4 ,7H 2 O) 
is formed, which is freely soluble. The latter salt may be obtained 
in large rectangular prisms* An acid sulphate (C 20 H 24 N 2 O 2 ,2H 2 SO 4 ,- 
7H 2 0) also exists. The Infusum Cinchonas, Acidum, B. P., contains 
the soluble sulphate. 

The ordinary quinine disulphate is more soluble in alcohol or 
alcoholic liquids than in water. An ammoniated tincture (Tinctura 
Quinince Ammoniata, B. P.) is made by dissolving the sulphate in 
proof spirit and adding a large excess of solution of ammonia. 
This tincture contains quinine itself liberated from combination by, 
and dissolved by aid of, the excess of the ammonia. Quinine wine 
( Yinum Quinince, B. P.) is a solution of neutral quinine sulphate 
and citrate in, orange wine, made by dissolving the disulphate (1 
grain in the ounce) in orange wine by the help of citric acid. The 
remaining pharmacopoeial preparations of quinine are the hydro- 
chlorate and the mixed iron, ammonium, and quinine citrates [Ferri 
et Quinince Citras, U. S. P.), the well-known scale compound. The 
latter is made by dissolving ferric hydrate, prepared from ferric 
sulphate, and quinine, prepared from the sulphate, in solution of 
citric acid ; the liquid, evaporated to a syrupy consistence and dried 
in thin layers on glass plates, yields the usual greenish-yellow scales. 
(Vide -p. 155.) 

Quinine Hydrochlorate (Quinince Hydrochloras, U. S. P.) is pre- 
pared by neutralizing quinine by hydrochloric acid. Its formula is 
C 20 H 24 N 2 O 2 ,HCl,2H 2 O. It is soluble in about 34 parts of water at 
common temperatures, the sulphate requiring 700 or 800. The two 
salts resemble each other in appearance, but the crystals of the 

* We do not know whether or not these sulphates are ordinary sul- 
phates, the hydrogen of the acid going over to the quinine molecule, nor 
whether or not the quinine molecule is univalent or bivalent ; hence we 
cannot say whether the common sulphate or the soluble sulphate is, in con- 
stitution, the neutral sulphate. In the above paragraph the names 
disulphate, neutral sulphate, acid sulphate indicate nothing more than 
that the first sulphate contains in one molecule two atoms (chemical 
atoms) of quinine to one of sulphuric acid, the second one of each, and 
the third two of acid to one of quinine. 



ALKALOIDS. 523 

hydrochlorate are commonly somewhat larger than those of the 
sulphate. 8 grains of hydrochlorate of quinine dissolved in 1 ounce 
of tincture of orange-peel forms the Tinctura Quinince, B. P. 

Quinince Hydrobromas, or Quinine Hydrobromate, U. S. P., has the 
formula C. 20 H^N 2 O 2 ,HBr,2H 2 O. 

Basic Quinine Citrate has the formula (C 20 H 24 N 2 O 2 ) 2 , H 3 C 6 H 5 O 7 ,- 
5H 2 0. Other citrates contain three molecules of quinine to two of 
citric acid, and one of quinine to one of citric acid. 

Quinince Valerianas, or Quinine Valerianate, U. S. P., may be 
made by dissolving precipitated quinine in warm aqueous solution 
of valerianic acid and setting aside to crystallize. Its formula is 



Reactions. 

First Analytical Reaction. — To a solution of quinine or its 
salts in acidulated water add fresh chlorine-water, shake, and 
then add solution of ammonia ; a green coloration (thalleioquin 
or dalleiochin) is produced. Bromine-water or bromine-vapor 
may be used instead of chlorine. 

Second Analytical Reaction. — Repeat the foregoing reaction, 
but precede the addition of solution of ammonia by that of 
solution of potassium ferrocyanide ; an evanescent red colora- 
tion is produced (Livonius and Vogel). 

Third Analytical Reaction. — To an aqueous solution of a sol- 
uble salt of quinine add .solution of ammonium oxalate ; a white 
crystalline precipitate of quinine oxalate falls. It is soluble 
in acids. If the solution to be tested be made from ordinary 
quinine sulphate, excess of the latter should be added to water 
very faintly acidulated with sulphuric acid, and the undissolved 
crystals removed by filtration. 

Fourth Analytical Reaction. — A saturated aqueous solution 
of any neutral salt of quinine is made by dissolving so much 
of the salt in hot water as that some shall separate when the 
mixture has cooled to about 60° F. After standing for some 
time, filter. To the filtrate water-washed ether is added until 
a distinct layer of ether remains undissolved, and then ammo- 
nia in slight excess. After agitation and rest for fifteen min- 
utes all precipitated quinine will have redissolved. 

Note. — In the case of quinidine salts well-defined crystals appear 
at the junction of the aqueous and ethereal layers, especially after 
standing. In the case of cinchonidine salts a thick layer of small 
crystals appears at once; In the case of cinchonine salts the un- 
dissolved alkaloid makes the ethereal layer nearly solid. In testing 
quinine for other alkaloids evaporate the aqueous solution to one- 
fifth. 

Fifth Analytical - Reaction. — Formation of Quinine Iodo-sul- 



524 ORGANIC CHEMISTRY. 

phate.— Dissolve quinine sulphate in weak spirit of wine slightly 
acidulated with sulphuric acid, and add an alcoholic solution 
of iodine ; a black precipitate forms. Allow the precipitate to 
settle, pour away the fluid, wash once or twice with cold alco- 
hol, and then boil with alcohol ; on cooling minute crystals 
separate, having the optical properties of the mineral tourma- 
line. This iodo-sulphate is sometimes termed herapathite, from 
the name of one of the chemists who discovered it (in 1852). 
Under the name of iodide of hydriodate of quinine Bouchar- 
dat described and used it in 1845. It is so slightly soluble in 
alcohol that by its means quinine can be fairly well separated 
from its admixture with the other cinchona alkaloids. Accord- 
ing to Jorgensen, it has the formula 4C 20 H 24 N 2 O 2 ,3H 2 SO 4 ,2HI r 
I 4 ,a;H 2 0. 

Sixth Analytical Reaction. — Prepare a saturated solution of 
ordinary quinine sulphate in water at about 60° F., and add to 
five volumes of that solution seven volumes of solution of 
ammonia (sp. gr. 0.96). The alkaloid which at first precipi- 
tates redissolves upon slight agitation if the quinine sulphate 
is free from anything but traces of other cinchona alkaloids. 
If, however, more than traces of quinidine, cinchonidine, and 
cinchonine salts be present, a permanent precipitate remains. 
This is Kerner's method of testing quinine sulphate for other 
cinchona alkaloids. It turns upon the fact that the solubility 
of the sulphates of the cinchona alkaloids in water is in the 
opposite order to the solubility of the alkaloids themselves in 
solution of ammonia. 

Other Characters. — Concentrated sulphuric acid dissolves 
quinine with production of only a faint yellow color, which is 

not increased by warmth. Quinine and its salts, heated on 

platinum-foil, burn entirely away. Most salts of quinine 

when in solution have a beautiful blue fluorescence. They 
twist the ray of polarized light to the left. Quinine is sol- 
uble in alcohol, ether, benzol, and chloroform. Ordinary qui- 
nine sulphate is insoluble in chloroform, and but slightly sol- 
uble in water. Its solubility in chloroform is increased by the 
presence in solution of quinidine and cinchonine sulphates 
(Prescott), and its solubility in water is decreased by the pres- 
ence in solution of ammonium sulphate (Carles). The slight 
solubility of its sulphate and iodo-sulphate in water distin- 
guishes quinine from the other cinchona alkaloids, including 
the " amorphous alkaloid," or " quinoidine." 

Quinidine (C 20 H 24 N 2 O 2 , the conquinine or conchinine of Hesse) is 
an isomer of quinine. Its salts are fluorescent, and give thalleioquin 



ALKALOIDS. 525 

with chlorine- or bromine-water and ammonia. They twist the ray 
of polarized light to the right. Quinidine is insoluble in water and 
sparingly soluble in ether (see Quinine, Fourth Analytical Reaction). 
It is soluble in alcohol, benzol, and chloroform. It is less soluble 
than quinine in ammonia, five volumes of a saturated aqueous 
solution of its ordinary sulphate requiring sixty to eighty volumes 
of ammonia solution (sp. gr. 0.96). Quinidine Sulphate (Quinidince 
Sulphas, U. S. P. 2(C 20 H 24 N 2 O 2 ),H 2 SO 4 ,2H 2 O) is more soluble in water 
and chloroform than quinine sulphate. Quinidine tartrate is soluble 
in water. The hydriodate is insoluble in water and weak spirit, and 
occurs as sandy crystals. The hydriodates of the other cinchona 
alkaloids, though more soluble than quinidine hydriodate, are some- 
times precipitated from neutral concentrated solutions as amorphous 
or semi-liquid precipitates. These, however, are soluble in weak 
spirit. 

" If a small quantity of ammonia-water be added to 3 cc. of an 
aqueous solution of the salt saturated at 15° C. (59° F.) a white pre- 
cipitate (quinidine) will be produced, which requires more than 
30 cc. of ammonia or more than thirty times its weight of ether to 
dissolve it (absence of more than small proportions of other cinchona 
alkaloids)."— U.S. P. 

Cinchonidine (C 20 H 24 N 2 O). — The sulphate (Cinchonidince Sulphas 
(C 20 H 24 N 2 O) 2 ,H 2 SO 4 ,3H 2 O, U. S. P.) is official. It may be obtained 
from the mother-liquids of the crystallization of quinine sulphate. 
When perfectly pure, salts of cinchonidine do not give thalleioquin 
and are not fluorescent. Even good commercial salts, however, 
nearly always give both reactions. Salts of cinchonidine twist the 
polarized ray to the left. Cinchonidine is insoluble in water and 
nearly so in ether. (See Quinine, Fourth Analytical Reaction.) It 
is soluble in alcohol, benzol, and chloroform. It is less soluble in 
ammonia solution than quinine, five volumes of a saturated aqueous 
solution of cinchonidine sulphate requiring about eighty volumes 
of ammonia solution (sp. gr. 0.96). It is true cinchonidine is dis- 
solved as readily as quinine if excess of strong ammonia is quickly 
mixed with the solution of the salt of cinchonidine, but from such 
a solution cinchonidine soon crystallizes out, while quinine remains 
dissolved for many hours. Cinchonidine sulphate and hydriodate 
are soluble in water, but the sulphate, like quinine sulphate, is 
insoluble in chloroform. Cinchonidine tartrate is insoluble in 
water, and in this form cinchonidine is usually separated from 
neutral solutions containing the other cinchona alkaloids except 
quinine, the filtrate from the precipitate of tartrate yielding cin- 
chonine on the addition of ammonia. 

Cinchonine (C 20 H 24 N 2 O) (Cinchonina, U. S. P.) is an isomer of 
cinchonidine. When quite pure its salts are not fluorescent and 
do not give thalleioquin. As in the case of cinchonidine, even 
good commercial specimens of cinchonia salts nearly always give 
both reactions. Cinchonine salts twist the polarized ray to the 
right. Cinchonine is insoluble in water and nearly so in ether. 
(See Quinine, Fourth Analytical Reaction.) It is soluble in chloro- 
form, benzol, and alcohol. Chloroform containing one-fourth of 
23* 



526 ORGANIC CHEMISTRY. 

its weight of 95 per cent, alcohol dissolves cinchonine much more 
readily than either alcohol or chloroform alone. Cinchonine is 
insoluble in ammonia solution. 

The sulphate (Cinchonince Sulphas, B. P.) is official. "It may 
be obtained from the mother-liquors of the crystallization of the 
quinine, cinchonidine, and quinidine sulphates by precipitating 
the alkaloid with caustic soda, washing it with spirit until free 
from other alkaloids, dissolving in sulphuric acid, and, after purify- 
ing the solution with animal charcoal, allowing to crystallize." 

Cinchonine Sulphate (Cinchonince Sulphas, U.S. P.) (C 20 H 24 N 2 O) 2 ,- 
H 2 S0 4 ,2H 2 0, tartate and hydriodate of cinchonine, are soluble in 
water, and the sulphate, like quinidine sulphate, is soluble in chlo- 
roform. In mixtures of cinchona alkaloids this alkaloid is precip- 
itated by alkali after the others have been successively removed by 
ether, sodium tartrate, and potassium iodide. 

Constitution of the Cinchona Alkaloids. — This is not yet clear, 
though great advances have been made. In the course of the inves- 
tigations derivatives of quinoline more or less resembling quinine 
have been obtained — namely, kairine, kairoline, and thalline; anti- 
pyrine also. (Acetanilide, or " antifebrin," has, too, been found to 
posess greater antipyretic powers than the derivatives just men- 
tioned.) See also p. 513. 

" Quinoidine" u Chinoidine" or the " Amorphous Alkaloid." — 
Cinchona-barks generally contain some alkaloid isomeric with 
quinine which, like quinine, is soluble in ether, but the ordinary 
sulphate and iodo-sulphate of which are not crystalline and are 
soluble. These salts are semi-solid resinous-looking substances. 
The iodo-sulphate is used in De Vrij's method for the separation 
of mixed alkaloids. Quinoidine is usually obtained along with 
quinine, etc. from the mixed alkaloids by ether, and remains in the 
mother-liquor, from which it is precipitated by an alkali. 

Cinchovatine occurs in a particular variety of cinchona-bark. 
Quinicine and cinchonicine are alkaloids produced by the action 
of heat on quinine or quinidine and on cinchonidine respectively. 
They, also, are isomers — Hesse says polymers — of the parent alka- 
loids. Both yield ordinary salts. Quiniretin is the name given to 
the brown or reddish-brown indifferent substance into which quinine 
in aqueous solution is converted when exposed to much light. 

Quinamine (C 20 H 26 N 2 O 2 ) is a fifth cinchona alkaloid obtained by 
Hesse in 1872 from the bark of Cinchona Succirubra. Its solution 
is not fluorescent, and does not give thalleioquin. The same chemist 
announces the presence in cinchona of a sixth alkaloid, cinchamidine 
(C 20 H 26 N 2 O). 

Cupreine (C 19 H 22 N 2 2 ) is an alkaloid discovered simultaneously by 
Howard and Hodgkin, by Paul and Cownley, and by Whiffen, in 
the bark of a Kemijia (allied to Cinchona) and termed cuprea-h&rk. 
It closely resembles quinine, but is sparingly soluble in ether. It 
may be converted into quinine by heating its sodium compound 
with methyl chloride ; whence it appears that quinine is the methyl 
ether of cupreine. The alkaloid, at first termed homoquinine or 
ultraquinine, seems to have been a mixture of cupreine and quinine. 



ALKALOIDS. 527 

Hydroquinine, C 20 H 26 N 2 O 2 , containing two more atoms of hydrogen 
than are present in the quinine molecule, is an alkaloid associated 
with quinine, in minute amount, in cinchona-bark. It remains in 
the mother-liquor when quinine sulphate is crystallized from an acid 
solution. Its therapeutic action is similar to that of quinine. Its 
characters are closely allied to those of quinine. It was discovered 
by Hesse. 

STRYCHNINE. 

Formula, C 21 H 22 N 2 2 . Molecular weight, 334. 

Source. — Strychnine or strychnia exists, to the extent of 0.2 to 
0.5 per cent., in the seed of Strychnos Nux-vomica {Nux Vomica, 
U. S. P.), also (Shenstone) in minute quantity in the bark of the 
nux-vomica tree (false Angustura-bark), and to 1.0 or 1.5 per cent, 
in St. Ignatius's bean {Strychnos Ignatia), chiefly in combination 
with strychnic or igasuric acid, or, after slight fermentation when 
moistened, with lactic acid. Crow also found it in the bark of the 
S. Ignatius. 

Process. — According to the British official process for its prepara- 
tion (Strychnina, B. P.), the seeds, disintegrated by subjection to 
steam, and, after drying, grinding in a coffee-mill, are exhausted 
with spirit, the latter removed by distillation, the extract dissolved 
in water, coloring and acid matters precipitated by lead acetate, the 
filtered liquid evaporated to a small bulk, the strychnine precipitated 
by ammonia, the precipitate washed, dried, and exhausted with 
spirit, the spirit recovered by distillation, and the residual liquid 
set aside to crystallize. Crystals of strychnine having formed, 
the mother-liquor (which contains the brucine of the seeds) is 
poured away, and the crystals of strychnine washed with spirit 
(to remove any brucine) and recrystallized. 

In the U. S. P. (1870) process the rasped nux vomica is exhausted 
by very dilute hydrochloric acid, milk of lime added to the evap- 
orated decoction to decompose the strychnine hydrochlorate, the 
precipitated and dried mixture of strychnine and lime treated with 
diluted alcohol to remove brucine, and then with strong hot alcohol 
to dissolve out strychnine •, the alcohol having been recovered by 
distillation, the residual impure strychnine is dissolved in very 
dilute sulphuric acid, the solution decolorized by animal charcoal, 
evaporated, and set aside to crystallize, the crystals of strychnine 
sulphate (Strychnino? Sulphas, U. S. P. ; (C 21 H 22 N 2 2 ) 2 H 2 S0 4 ,5H 2 5 
Coleman, 6H 2 0) redissolved in water, ammonia added to precipitate 
pure strychnine, and the latter dried. 

Properties. — Strychnine occurs " in right square octahedrons or 
prisms, colorless and inodorous ; sparingly soluble in water, but 
communicating to it an" intensely bitter taste ; soluble in boiling 
rectified spirit and in chloroform, but not in absolute alcohol or in 
ether." It forms salts with acids. The citrate, (C 21 H 22 N 2 2 ) 2 C 6 H 8 7 ,- 
4H 2 (or 6H 2 0), dissolves, at 60° F., in about 40 parts of water and 
115 parts of alcohol. The hydrochlorate seems to have the formula 
C 21 H 22 N 2 2 HC1,3H 2 0, and (Dott) is soluble in 35£ parts of water. 



528 ORGANIC CHEMISTRY. 

Reactions. 

First Analytical Reaction. — Place quite a small fragment of 
strychnine on a white plate, and near to it also a small piece 
of red potassium chromate ; to each add one drop of concen- 
trated sulphuric acid; after waiting a minute or so for the 
chromate to fairly tinge the acid, draw the latter, by a glass 
rod, over the strychnine spot ; a beautiful purple color is pro- 
duced, quickly fading into a yellowish red. The following 
oxidizing agents may be used in the place of the chromate : 
puce-colored lead oxide, fragments of black manganese oxide, 
potassium ferricyanide, or potassium permanganate. 

This reaction is highly characteristic : a minute fragment dis- 
solved in much dilute alcohol — or, better, chloroform — and one drop 
of the liquor evaporated to dryness on a porcelain crucible-lid or 
other white surface, yields a residue which immediately gives the 
purple color on being oxidized in the manner directed. 

Other Reactions. — Strong sulphuric acid does not act on strychnine, 
even at the temperature of boiling water — a fact of which advantage 
is taken in separating strychnine from other organic matter for the 
purposes of toxicological analysis. Potassium sulphocyanate pro- 
duces, even in dilute solutions of strychnine, a white precipitate, 
which under the microscope is seen to consist of tufts of acicular 

crystals. Strong nitric acid does not color strychnine in the cold, 

and on heating only turns it yellow. 

The Physiological Test. — A small frog placed in an ounce of water 
to which t £q of a grain of strychnine salt (acetate) is added is in 
two or three hours seized with tetanic spasms on the slightest touch, 
and dies shortly afterward. 

Strychnine has an intensely bitter taste. Cold water dissolves 
only 20V0 part, yet this solution, even when largely diluted, is dis- 
tinctly bitter. Alcohol is a somewhat better solvent. The salts of 
the alkaloid are more soluble. The official solution {Liquor Strych- 
nince Hydrochloratis, B. P.) contains 1 per cent, of strychnine, the 
solvent being 3 parts water, 1 part spirit, and a few minims (6 per 
ounce) of hydrochloric acid (rather more than sufficient to form 
strychnine hydrochlorate). If too much acid be present, the hydro- 
chlorate will crystallize out in cold weather. A syrup of phosphates 
of iron, quinine, and strychnine is official (Syrupus Ferri, Quinince 
et Strychnine Phosphatum). It contains 1 part of strychnine in 
5000. 

Brucine, or Brucia (C 23 H 26 N 2 4 ,4H 2 0), is an alkaloid accom- 
panying strychnine in nux vomica and St. Ignatius' s bean to the 
extent of about 2 per cent. It is readily distinguished by the 
intense red color produced when nitric acid is added to it. Igasurine, 
once supposed to be a third alkaloid of nux vomica, has been shown 
by Shenstone to be only a mixture of brucine and strychnine. 

Curarine (C 10 H 15 N), the active principle of the arrow-poison 
termed curari, urari, ourari, wourali, or ivoorara, prepared from 



ALKALOIDS. 529 

a Strychnos, resembles strychnine in giving color by oxidation, but 
the color is more stable. Potassium iodide or platinocyanide does 
not with curarine afford precipitates which crystallize from alcohol 
like those of strychnine. Curarine also is soluble in water. Unlike 
strychnine, curarine is reddened by sulphuric acid; it also is not 
dissolved out by ether from an acid or alkaline liquid. Curari 
appears to vary much in strength and quality. It is probably 
a mixture of vegetable extracts. 

Distinction of Brucine from Morphine. — The red coloration pro- 
duced by the action of nitric acid on brucine is distinguished from 
that yielded with morphine by the action of reducing agents (such 
as stannous chloride, sodium hyposulphite, sodium sulphydrate), 
which decolorize the morphine-red, but change that of the brucine 
to violet and green (Cotton). The solution of brucine in the nitric 
acid should be heated to the boiling-point, diluted with water, and 
the stannous chloride then be added. 

Distinction of Free Alkaloids or their Salts from Each Other. — 
This is accomplished by remembering the appearance and other 
physical characters of the substances as met with in pharmacy, the 
effect of heat, the action of such solvents as water, alcohol, and 
ether, the influence of strong and diluted acids, strong and weak 
alkalies, oxidizing substances, and other reagents. (Tables to aid 
in the analysis of small quantities of official alkaloids, their salts, 
glucosides, and various " scale " compounds, will be found opposite 
p. 544.) 



QUESTIONS AND EXEECISES. 

What alkaloids are more or less characteristic of the different varieties 
of cinchona-bark? In what form do they occur?— By what method is 
sulphate of quinine obtained ? — Give the characters of quinine sulphate. 
— Describe the tests for quinine. — How would you detect salicin in quinine 
sulphate? — Show how the quinidine or cinchonine sulphates may be 
proved to be present in commercial quinine sulphate. — How are cincho- 
nine and quinine distinguished from morphine? — Whence is strychnine 
obtained? — Describe the official process for the isolation of strychnine. — 
Give the characters of strychnine. — Describe the tests for strychnine. — 
By what reagent is brucine distinguished from strychnine? — Distinguish 
between brucine and morphine. — By what general methods would you 
distinguish common alkaloids from each other? 



ALKALOIDS OF LESS FREQUENT OCCURRENCE. 

Aconitiste, Aconitina, or Aconitia is an alkaloid obtained from 
aconite (Aconitum Napellus) leaves (Aconiti Folia, B. P.) and root 
(Aconitum, U. S. P.). The alkaloid itself is only slightly soluble in 
water ; it occurs in the plant in combination with a vegetable acid, 
forming a soluble salt. 

Process. — The official process for its preparation (Aconitina, B. P.) 
consists in dissolving out the natural salt of the alkaloid from the 
root by rectified spirit, recovering the latter by distillation, mixing 



530 ORGANIC CHEMISTRY. 

the residue with water, filtering, precipitating the aconitine by 
ammonia, drying the precipitate and digesting it in ether (in which 
some of the accompanying impurities are insoluble), recovering the 
ether by distillation, dissolving the dry residue in the retort in 
water acidulated by sulphuric acid, again precipitating the alkaloid 
by ammonia, and finally washing and drying. 

Properties. — Aconitine usually occurs as a white powder. It has 
been obtained and studied in the crystalline state by Groves, Wright, 
Williams, and others. It is very slightly soluble in cold water, 
more so in hot, and much more soluble in alcohol, in ether, and in 
chloroform. It is one of the most violent poisons known. " When 
rubbed on the skin it causes a tingling sensation, followed by pro- 
longed numbness." The thousandth part of a grain on the tip of 
the tongue produces, after a minute or so, a characteristic tingling 
sensation and numbness 5 large quantities rubbed into the skin cause 
numbness and loss of feeling. Sulphuric acid turns it of a yellow- 
ish, and afterward dirty violet, color. 

According to Wright, who, in conjunction with Groves and 
Williams, worked by the aid of grants from the British Pharma- 
ceutical Conference, Aconitum Napellus yields, chiefly, crystal- 
line aconitine, C 33 H 43 N0 12 , with some crystalline pseud-aconitine, 
C 36 H 49 N0 12 , and a little non-crystalline alkaloid. 

In the research laboratories of the Pharmaceutical Society of 
Great Britain, Dunstan and Umney found, in addition to aconitine 
(C 33 H 45 N0 12 , Dunstan and Ince), aconine and an amorphous alkaloid, 
napelline or isaconitine, whose salts are also uncrystallizable. It is 
isomeric with aconitine, and also yields the 'same products on hydrol- 
ysis. Aconitine is readily hydrolyzed into aconine, C 26 H 41 NO n , 
and benzoic acid (Dunstan and Passmore). 

According to Jurgens, the formula of aconitine is C 33 H 47 N0 12 . 
On allowing an acetic solution containing potassium iodide to evap- 
orate to dryness, and then adding water, crystals of aconitine 
hydriodate of characteristic appearance remain. 

The tuberous roots of Aconitum Ferox and other species consti- 
tute the bish or bikh of India (Aconiti Ferocis Radix, P. I.). It 
chiefly contains the variety of aconitine termed pseudaconitine. 
Some of the aconitine of pharmacy is pseudaconitine. 

According to Paul and Kingzett, the alkaloid of Japanese aconite 
has the formula C 29 H 43 N0 9 , while Wright and Menke state that the 
formula is C 66 H 88 N 2 21 , and the name is japaconitine. 

Unguentum Aconitince, B. P., contains 8 grains of the alkaloid to 
1 ounce of benzoated lard. 

Aconitum heterophyllum, Atis, or Atees, or Wakhma (Aconiti 
Heterophylli Radix, P. I.), contains no aconitine, but an alkaloid, 
ateesine, having the formula C 46 H 74 N 2 5 . 

Aspidospermine, C 22 H 30 N 2 O 2 , is an alkaloid of Quebracho bianco 
bark (Fraude). Another and different alkaloid is quebrachine 
(C 21 H 26 N 2 3 ) (Hesse). The latter chemist has isolated four other 
closely related alkaloids, and two from Quebracho Colorado bark. 

Atropine, or Atropia (C 1Y H 23 N0 3 ). — This alkaloid has hitherto 
been considered to exist ready formed in the belladonna or deadly 



ALKALOIDS. 531 

nightshade (Atropa Belladonna ; Belladonna? Folia et Radix, U. S. 
P.) as soluble acid atropine malate. But the observations of Messrs. 
Schering and the researches of Will indicate that not atropine, but 
an isomer of atropine — namely, hyoscyamine — is the alkaloid chiefly 
and often solely present, and that the alkaline treatment during the 
process of extraction converts the hyoscyamine into atropine. 
Hyoscyamine solutions rotate a plane-polarized ray to the left-, 
atropine has no optical rotatory power. Each similarly affects the 
eye. 

Process. — Atropine is obtained by exhausting the root with spirit, 
precipitating the acid and some coloring-matter by lime, filtering, 
adding sulphuric acid to form atropine sulphate (which is somewhat 
less liable to decomposition during subsequent operations than the 
alkaloid itself), recovering most of the spirit by distillation, adding 
water to the residue, and evaporating till the remaining spirit is 
removed ; solution of potassium carbonate is then poured in till the 
liquid is nearly but not quite neutral, by which resinous matter is 
precipitated : the latter is filtered away, excess of potassium carbo- 
nate then added, and the liberated atropine dissolved out by shaking 
the liquid with chloroform. The latter solution, having subsided, 
is removed, the chloroform recovered by distillation, the residual 
atropine dissolved in warm spirit, coloring-matter separated by digest- 
ing the liquid with animal charcoal, the solution filtered, evaporated, 
and set aside to deposit crystals. 

Solubility. — Atropine is sparingly soluble in water, the liquid 
giving an alkaline reaction — more soluble in alcohol and ether. 

Tests. — Atropine solutions give with gold perchloride a yellow 
precipitate. 1 drop of a dilute aqueous solution (2 grains to the 
ounce) powerfully dilates the pupil of the eye. It is generally 
applied on a piece of thin tissue-paper or small disk (Lamellce 
Atropines , B. P.) placed between the eyelid and the eye. Hom- 
atropine hydrobromate is official (Homatropince Hydrobromas, B. P.). 
It is a white crystalline powder or aggregation of minute prismatic 
crystals, soluble in 6 parts of cold water and in 133 of ethylic alcohol. 
The dilute aqueous solution powerfully dilates the pupil of the eye. 
A 2 per cent, aqueous solution is not precipitated by the cautious addi- 
tion of solution of ammonia previously diluted with twice its volume of 
water [distinction from atropine]. About ^ of a grain moistened 
with 2 minims of nitric acid and evaporated to dryness on the water- 
bath yields a residue which is colored yellow by an alcoholic solu- 
tion of potash [distinction from atropine, hyoscine, and hyoscyamine]. 
If about T X o of a grain be dissolved in a little water and the solution 
be made alkaline with ammonia and shaken with chloroform, the 
separated chloroform will leave on evaporation a residue which will 
turn yellow, and finally brick-red, when warmed with about 15 
minims of a solution of 2 grains of mercury perchloride in 100 
minims of proof spirit. For Gerrard, Schweissinger, and Fluckiger 
have observed that homatropine (Ladenburg's oxytoluyltropeine, a 
physiologically similar but less powerful, and therefore sometimes 
more useful, alkaloid than atropine), like hyoscyamine and atropine, 
has unusually powerful alkaline properties, precipitating mercuric 



532 ORGANIC CHEMISTRY. 

oxide from mercuric solutions, reddening phenolphthalein, and, 
with warmth, blackening calomel. No other ordinary alkaloids are 
so powerfully alkaline. 

"Baryta-water decomposes atropine into tropine (C 8 H 15 NO) and 
tropic acid (C 9 H 10 O 3 ), a molecule of water being absorbed ; hence the 
atropine, so called, would seem to be tropine tropate, minus water, 
or tropyl-tropine. Indeed, Ladenburg by heating tropic acid and 
tropine in sealed tubes has produced a base indistinguishable from 
atropine. The same chemist by removing the elements of water 
from tropine gets tropidine, C 8 H 13 N, closely related to ecgonine 
(p. 534) and anhydro-ecgonine. This is, possibly, an intermediate 
member of a group of alkaloids, of which others are conine, C 8 H 15 N, 
and colliding C 8 H n N, the latter a product of the destructive distilla- 
tion of bone oil, coal, quinine, etc. Commercial atropine is said by 
Regnauld and Valmont to be a mixture of true atropine with hyos- 
cyamine. 

In the so-called Japanese belladonna (Scopola Japonica) occurs 
scopoleine, an alkaloid resembling but more powerful than atropine 
(Eyckmann), but Schmidt considers that only atropine, hyoscyamine, 
and hyoscine are present. 

Preparations. — The alkaloid itself (Atropina) and the Sulphate of 
Atropine (Atropina? Sulphas, or Atropine Sulphate, (C 17 H 23 N0 3 ) 2 H 2 - 
S0 4 , a colorless powder soluble in water, made by neutralizing atro- 
pine with sulphuric acid), are official in the United States Pharma- 
copoeia. 

The fluorescence of alkaline solutions of extract of belladonna is 
caused by chrysatropic acid, C 12 H 10 O 5 (Kunz), probably allied to the 
fluorescent scopoletin,, C 10 H 8 O 4 , found in Japanese belladonna by 
Eyckmann. 

Baptitoxine. — Schroeder gives this name to a poisonous alkaloid 
in Baptisia tinctoria, wild indigo, in which he also finds the gluco- 
sides baptisin and baptin. 

Beberine, Bebirine, or Bibirine (C 36 H 42 N 2 6 ) is an alkaloid in 
the bark of bebeeru or bibiru [Nectandra Eodicei). 

Process. — According to the British Pharmacopoeia, it — or rather 
its sulphate, C 36 H 42 N 2 6 ,H 2 S0 4 (Beberince Sulphas, B. P.) — may be 
prepared by exhausting the bark (Nectandrce Cortex, B. P.) with 
water acidulated by sulphuric acid, concentrating, removing most 
of the acid by lime, filtering, precipitating the alkaloid by ammonia, 
filtering, drying, dissolving in spirit (in which some accompanying 
matters are Insoluble), recovering most of the spirit by distillation, 
neutralizing by diluted sulphuric acid, evaporating to dryness, dis- 
solving the residual sulphate in water, evaporating to the consistence 
of a syrup, and spreading on glass plates, drying the product at 
140° F. Thus obtained, it occurs in dark-brown translucent scales, 
yellow when powdered, strongly bitter, soluble in water and in 
alcohol. It is probably a mixture of sulphates of beberine, nectan- 
drine, and other alkaloids. 

Tests. — Alkalies give a pale-yellow precipitate of beberine when 
added to an aqueous solution of a salt of the alkaloid ; the precipi- 
tate is soluble in ether. With red potassium chromate and sul- 



ALKALOIDS. 533 

phuric acid beberine gives a black resin, and with nitric acid a 
yellow resin. 

Buxine, from the bark of Buxus sempervirens ; Pelosine, or Cissam- 
peline, from the root {Pareirae, U. S. P.) of Cissampelos Pareira ; 
and Paricine, from a false Para cinchona-bark, — are probably identi- 
cal with beberine (Fluckiger). 

Nectandrine (C 40 H 46 N 2 O 8 ,4H 2 O). — Drs. Maclagan and Gamgee a 
few years ago discovered this second alkaloid in bebeeru-bark. It 
differs from beberine in fusing when placed in boiling water, in 
being much less soluble in ether, in giving with strong sulphuric 
acid and black manganese oxide a beautiful green and then violet 
coloration, and in having a distinct molecular weight. They con- 
sidered that two other alkaloids exist in bebeeru-bark. 

Berberine (C 20 H 17 NO 4 ) is an alkaloid existing in several plants 
of the natural order Berberideoz (three species yield Indian Barberry, 
Berberis Cortex, P. I.), in calumba-root (Calumbce, U. S. P.), in the 
root of Coptis Teeta, or Mishmi Bitter {Coptidis Radix, P. I.), an 
Indian tonic, and in many other yellow woods. Hydrastis Cana- 
densis, or Golden Seal {Hydrastis, U. S. P.), contains berberine, 
though another alkaloid, hydrastine {vide page 537) (C 22 H 23 N0 6 ), 
related to narcotine (which seems to be methoxyl-hydrastine ; 
Schmidt) and to papaverine, and even a third, are asserted to be 
present, all, in Perkin's opinion, benzene derivatives of iso-quinoline. 
The dried rhizome and rootlets are official, Hydrastis Rhizoma, B. P., 
and these are the source of Extracttmi Hydrastis Liquidum, B. P., 
Tinctura Hydrastis, B. P, and Glyceritum Hydrastis, U. S. P. The 
root of Berberis vulgaris contains berberine and (Wacker) oxyacan- 
thine (C 18 Hj 9 N0 3 ; C 19 H 21 N0 3 , Rudel), as well as (Hesse) berbamine 
(also C 18 H 19 N0 3 ). Xantkorrhiza apii folia, an old American tonic, 
and, apparently, Xanthoxylon Fraxineum, or prickly-ash bark 
(Xanthoxylum, U. S. P.) also contain berberine. The rhizome of 
Menispermum Canadense, Yellow Parilla, or Canadian Moonseed 
{Menispermum, U. S. P.), contains, according to Maisch, a colorless 
alkaloid as well as berberine. The color of the tissues of these vege- 
tables is apparently due to berberine, for the alkaloid itself is remark- 
able for its beautiful yellow color. 

Tests. — When a dilute solution of iodine and potassium iodide is 
added to a solution of any salt of berberine in hot spirit, excess of 
iodine being carefully avoided, brilliant green spangles are de- 
posited. The reaction is sufficiently delicate to form, according to 
Perrins, an excellent test of the presence of berberine. This iodo- 
compound polarizes light and has other analogies with herapathite. 

Berberine itself is not official, but plants in which it occurs are 
used as medicinal agents in all parts of the world. 

Process. — Berberine is readily extracted by boiling the raw 
material with water, evaporating the strained liquid to a soft extract, 
digesting the residue in alcohol, recovering the alcohol by distilla- 
tion, boiling the residue with diluted sulphuric acid, filtering, and 
setting aside ; berberine sulphate separates out, and may be purified 
by recrystallization from hot water. The neutral sulphate, (C 20 H 17 - 
N0 4 ) 2 H 2 S0 4 , is very soluble in water ; the acid sulphate, C 20 H 17 NO 4 ,- 



534 ORGANIC CHEMISTRY. 

H 2 S0 4 , is less soluble. The alkaloid itself is obtained by shaking 
lead hydrate with a hot aqueous solution of the berberine sulphate 
(Procter). 

Caffeine.— See Theine. 

Capsicine. — M. Felletar obtained from capsicum-fruits ( Capsicum, 
U. S. P.), which when ground form Cayenne pepper, a volatile alka- 
loid having the smell of conine. Thresh has obtained crystalline 
hydrochlorate and sulphate. The latter chemist has also succeeded 
in isolating the active principle of capsicum, which he has termed 
capsaicin, (C 9 H 14 2 ), a crystalline non-alkaloidal, excessively acrid 
substance. Its exact chemical character is not yet made out. Accord- 
ing to Dr. Thresh, a similar pungent principle occurs in ginger 
(gingerol) and in grains of paradise (paradol), bodies probably 
isomeric with capsaicin. (See also Capsicin in Index.) 

Carpaine, C 14 H 2V N0 2 , occurs in Carica papaya. 

Chelidonine (C 19 H 17 N 3 3 ) and Chelertthrine (C 19 H 17 N0 4 ), the 
latter identical, apparently, with sanguinarine, are two alkaloids 
occurring in Celandine {Chelidonium, U. S. P.), associated with 
citric, malic, and chelidonic (C 7 H 4 6 ) acids. (See p. 541.) 

Cocaine (C 17 H 21 N0 4 ) is an alkaloid of Erythroxylon Coca {Coca, 
U. S. P.), the leaves of which act powerfully as a restorative to the 
human system. The hydrochlorate of the alkaloid is official 
{Cocainoz Hydrochloras, U. S. P.) ; also a 10 per cent, solution of 
the same {Liquor Cocaince Hydrochloratis, B. P.), preserved by aid 
of salicylic acid. Cocaine and its salts may be prepared by agita- 
ting with petroleum spirit a strong, acidulated, aqueous extract of 
the leaves made alkaline with sodium carbonate, well shaking the 
separated spirit with acidulated water, treating the separated acid 
fluid with ether and excess of sodium carbonate, washing out the 
alkaloid from the ether by water acidulated with hydrochloric acid, 
and finally evaporating the resulting aqueous solution of the hydro- 
chlorate to the crystallizing point. Cocaine may be precipitated 
with ammonia and recrystallized from alcohol, ether, or warm 
benzene. From this pure cocaine the pure and very soluble hydro- 
chlorate may be prepared by neutralizing with hydrochloric acid 
and crystallizing. 

Prolonged contact of cocaine with hot water, acids, alkalies, or 
even alcohol, is undesirable, as cocaine readily breaks up into ben- 
zoyl-ecgonine and methylic alcohol, C 17 H 21 N0 4 -f- H 2 = C 16 H 19 N0 4 
+ CH 3 OH, benzoyl-ecgonine afterward yielding ecgonine and ben- 
zoyl-hydrate or benzoic acid, C 16 H 19 N0 4 + H 2 = C 9 H 15 N0 3 -f- 
C 7 H 6 2 . In coca other bases occur with cocaine. Paul and Cown- 
ley, also Giesel, find cinnamyl-cocaine. Hesse finds cocamine and 
cocaidine, isomeric with cocaine. Liebermann finds several bases, 
one of which is poisonous — namely, isatropylcocaine, C 19 H 23 N0 4 , 
containing isatropyl in place of the benzoyl group in ordinary 
cocaine. It has an amorphous and sticky appearance. All these 
bases are easily hydrolyzed, yielding ecgonine ; the latter with 
benzoic anhydride yields benzoyl-ecgonine, and this, with methyl 
iodide or otherwise, yields benzoyl-methyl ecgonine or ordinary 



ALKALOIDS. 535 

cocaine. By thus building up with other acidulous bodies than the 
benzoic a whole chemical series of " cocaines " can be produced. 

Another alkaloid (benzoyl-pseudotropeine), yielding instead of 
ecgonine a compound isomeric with tropine, also occurs in coca 
(Griesel, Liebermann). Cinnamyl-cocaine and other coca bases are 
officially detected by the following test: " If 1 drop of a mixture 
of one volume of decinormal potassium permanganate and two vol- 
umes of water be added to 5 cc. of a 2 per cent, solution of cocaine 
hydrochlorate mixed with 3 drops of diluted sulphuric acid, and con- 
tained in a small, clean, glass-stoppered vial, the pink tint produced 
by the permanganate should not entirely disappear within half an 
hour."— U. S. P. 

Cocaine hydrochlorate occurs in colorless acicular crystals or a 
white crystalline powder, soluble in water, chloroform, alcohol, 
amylic alcohol, very slightly in ether ; not readily decomposed even 
when boiled in water. On heating a small amount of the powdered 
cocaine hydrochlorate for twenty minutes on a water-bath, no 
material loss should occur (absence of water of crystallization). 
When ignited it should burn completely away. If a small quantity 
of the hydrochlorate be rubbed with a glass stirrer, on the bottom 
of a dry white porcelain dish, with an equal amount of mercuric 
chloride, and the mixture then breathed upon, it will turn to a 
grayish-white color. "On adding 5 drops of a 5 per cent, solution of 
chromic acid to 5 cc. of a 2 per cent, solution of cocaine hydrochlo- 
rate, a yellow precipitate is produced which redissolves on shaking ; 
on now adding 1 cc. of hydrochloric acid a permanent orange-yellow 
precipitate will be formed." — U. S. P. The free alkaloid is readily 
decomposed by water, especially when the solution is warmed. The 
solution in water has a bitter taste, and produces on the tongue a 
tingling sensation followed by numbness. The aqueous solution 
dilates the pupil of the eye. It gives no color to cold strong acids, 
but chars with hot sulphuric acid, and gives a purple precipitate 
with permanganates and a white precipitate with ammonia. Evap- 
orated to dryness on a water-bath with nitric acid, and treated with 
alcoholic potash, it develops an odor resembling peppermint. Besides 
its action as a restorative when taken internally, cocaine brought 
into contact with the mucous membrane of the eye, mouth, throat, 
etc. produces local anaesthesia. According to Squibb, good cocoa 
yields .5 per cent, of cocaine. Cocaine may be detected in presence 
of other alkaloids by giving a yellow precipitate of the chromate 
with potassium chromate or chromic acid in presence of free hydro- 
chloric acid. 

Colchicine, the active principle of Colchicum autumnale (Colchici 
Cormus, B. P. ; Colchici Seme?i, U. S. P.), is said to be an alkaloid, 
though some investigators think it has more of the characters of a 
neutral substance, and give it the name colchicin. Hertel gives it 
the formula C 7 H 23 N0 6 , and states that ebullition with acidulated 
water converts it into colchicein, C 16 H 21 N0 5 2H 2 0, and methyl alcohol. 
Zeisel says it may be crystallized from chloroform, and offers the 
following formulae for it and its derivative : colchicin, C 21 H 22 (OCH 3 )- 
N0 5 ; colchicein, C 21 H 22 (OH)N0 5 . The most active medicinal prep- 



536 ORGANIC CHEMISTRY. 

aration is an extract made from the fresh seeds by digestion in 
large volumes of alcohol of at least 90 per cent., and subsequent 
digestion of the marc in hot water. The extracts left on evaporating 
the two fluids separately are to be carefully mixed (Mols). 

Conine, Conia, Conylia, Conicine, or Cicutine. — Formula, 
C 8 H 17 N (Hofmann), or a-normal-propijl-piperidine, C 5 H 10 N(C 3 H 7 ). 
This alkaloid is a volatile liquid, occurring in hemlock (Conlum 
maculatum) in combination with an acid (malic?). It is not official. 
According to Petit, its boiling-point is 170° C. and its density 0.846. 
It forms crystalline salts. 

Process. — It may be obtained by distilling hemlock-fruit (Co- 
nium, U. S. P.) with water rendered slightly alkaline by caustic 
soda or potash, or by similarly treating the fresh juice of the 
leaves. The alkaloid is a yellow oily liquid floating on the water 
that distils over ; by redistillation it is obtained colorless and trans- 
parent. 

The salts of conine have no odor, but when moistened with solu- 
tion of an alkali yield the alkaloid, the strong smell of which, at 
once recalling hemlock, is characteristic. Juice of hemlock-leaves 
{Conii Folia, B. P.), to which solution of potash and boiling water 
has been added, forms the official inhalation of conine ( Vapor 
Coninee, B. P.). 

Tests. — Sulphuric acid turns conine purplish red, changing to 
olive-green ; nitric acid a blood-red ; gold perchloride produces a 
yellowish-white precipitate, platinum perchloride no precipitate, in 
aqueous solutions. 

Hemlock also contains methyl-conine, (C 8 H 16 ) // CH 3 N ?) (Kekule 
and Von Planta), and conhydrine, C 8 H 17 NO. 

The latter by dehydration yields a base, C 8 H 15 N. Kekule' s base 
is probably a methylic derivative of this, C 8 H U CH 3 N, and not true 
methyl-conine. 

According to Schiff, conine, isomeric at least with the natural 
alkaloid, may be produced artificially by action of ammonia on 
butyric aldehyde and destructive distillation of the resulting com- 
pound. Ladenburg has produced conine identical with the natural 
alkaloid from a-picoline. Conine may now therefore be said to be 
a product of organic synthesis, producible from its elements. 

Corydaline is an alkaloid obtained by Wenzell from " turkey 
corn," the tubes of Dicentra (Corydalis) formosa. 

Cusparine (C 20 H 19 NO 3 ), with cusparidine (C 19 H 17 N0 3 ) and gali- 
pine (C 20 H 21 NO 3 ), are alkaloids occurring in the bark of Galipea 
cusparia, or true Angostura bark (Cusparice Cortex, B. P.). The 
bitter principle, angosturin, is not an alkaloid. 

Cytisine, or Ulexine, is an alkaloid found in laburnum and 
furze, and is also probably identical with sophorine, from Sophora 
tomentosa. 

Daturine. — Vide Hyoscyamine. 

Delphine or Delphinine and Delphinoidine are the poisonous 
alkaloids of stavesacre {Delphinium Staphisagria). The powdered 
seeds of the plant are employed to kill the pediculi. of animals. The 
seeds (Staphisagrice Semina, B. P.) contain about 25 per cent, of 



ALKALOIDS. 537 

oil. Unguentum Staphisagrias, B. P., contains about 10 per cent, 
of oil. 

Ditamine (Jobst and Hesse), present in the ditain of Gruppe, is 
an alkaloid of " dita," or bark of Eschites scholaris or Alstonia 
scholaris {Alstonias Cortex, P. I.), a reputed febrifuge. Others are 
echitamine and echitenine. Oberlin and Schlagdenhauffen state that 
the allied Alstonia constricta (the bark of which is said to have 
advantages over the hop as a dietetic bitter) contains a crystalline 
alkaloid, alstonine, and uncrystallizable alstonicine. Alstonine 
seems to be allied to strychnine. 

Duboisine. — Vide Hyoscyamine. 

Emetine (CgoH^NjC^, Glenard ; C 30 H 40 N 2 O 5 , Kunz). — This alka- 
loid is the active emetic principle of the root of Cephaelis Ipecacu- 
anha {Ipecacuanha, U. S. P.). It occurs to the extent of 1 to 2 per 
cent, in the root, less in the stems, in combination with ipecacuanhic 
acid. The nitrate is peculiarly slightly soluble in water (Lefort). 
In the Pulvis Ipecacuanhas et Opii, U. S. P., or "Dover's powder" 
(powdered ipecacuanha, 1 part ; powdered opium, 1 part : and sugar 
of milk, 8 parts), minute division of the active ingredients is pro- 
moted by prolonged trituration with sugar of milk, which is a very 
hard salt. Ipecacuanha Wine (Vinum Ipecacuanhas, B. P.) is a 
solution of neutral emetine acetate and of other matters extracted 
(by aid of acetic acid) from the root in sherry wine. Acetum Ipe- 
cacuanhas, B. P., is obtained from 1 part of root in 20 of diluted 
acetic acid. Choline (Arndt, a "volatile base") has been found in 
ipecacuanha. Ipecacuanha is said to have pharmacological activity 
(in dysentery) even after all emetine has been extracted ; hence it 
would seem to contain more than one active principle. 

The Indian substitute of ipecacuanha is the dried leaf {Tylophoras 
Folia, P. I.) of Tylophora asthmatica. Its active principle has not 
been satisfactorily isolated. 

Gelsemine (C n H 19 N0 2 , Sonnenschein ; C 12 H u N0 2 , Gerrard ; C 54 H 69 - 
N 4 12 , Thompson) is one of the alkaloids of Gelsemium nitidum, or 
Carolina yellow jasmine {Gelsemium, U. S. P.), in the tissues of 
which plant the gelseminic acid of Wormley, and ossculin (C 15 H 16 9 ), 
the fluorescent glucoside of the horse-chestnut and of many other 
plants, are also present. Like strychnine, gelsemine is not appar- 
ently affected by strong sulphuric acid. Nitric acid does not color 
it. A mixture of sulphuric acid and manganese peroxide colors it 
a crimson red, changing to green. In Gelsemium elegans Crow finds 
an allied alkaloid which does not resist the action of strong sulphuric 
acid. Gelseminine is another alkaloid said to be more powerful than 
gelsemine. 

Grindeline is the name given by Fischer to a bitter crystalline 
alkaloid he extracted from Grindelia Robusta {Grindelia ; Extraction 
Grindelia Fluidum, U. S. P.). The plant also contains resin and 
volatile oil. 

Guarine. — Vide Theine. 

Hydrastine, C 21 H 21 N0 6 , is a colorless alkaloid obtained from 
Hydrastis {vide p. 533) ; on oxidation with dilute nitric acid it yields 
opianic acid (C 10 H 10 O 5 ) and hydrastinine. 



538 ORGANIC CHEMISTRY. 

Hydrastinine (C 11 H 11 N0 2 ) is an artificial alkaloid obtained from 
hydrastine, as above, in white needles. The hydrochlorate is official 
(Hydrastininoz Hydrochloras, U. S. P.) ; it is a light-yellow acid 
powder, without odor, having a strong bitter but saline taste, deli- 
quescent when exposed to moist air, soluble in water (very dilute 
solution has a blue fluorescence) and alcohol, but only very slightly 
in chloroform and ether. Pure hydrastinine hydrochlorate should 
burn away without leaving a residue. 

Test. — " On adding to 2 cc. of an aqueous solution of the salt (1 
in 100) an excess of bromine-water a yellow precipitate is produced, 
which is dissolved by ammonia-water to a nearly colorless liquid 
(difference from hydrastine, with which the ammonia produces a 
brick-red precipitate).'' — IT. S. P. 

Hyoscine. — This is an alkaloid which is supposed to be identical 
with " scopolamine 1 ' (C 17 H 21 N0 4 ), from the Scopola atropoides and 
S. camialica, a tropate of another alkaloid isomeric (but not iden- 
tical, Hesse, Schmidt) with tropine. Hyoscine hydrobromate 
(C n H 21 N0 4 ,HBr -\- 3H 2 0) is official (Hyoscince Hydrobromas, U. S. 
P.). It crystallizes in colorless rhombohedra, which are neutral 
and easily soluble in water and alcohol ; very slightly so in chloro- 
form and ether. Heated to 100° C, the salt loses its water of crys- 
tallization, and on ignition burns completely. 

Test. — " If 5 drops of fuming nitric acid be added to 0.01 grm. of 
the salt in a small porcelain capsule, and the mixture be evaporated 
to dryness on a water-bath, a scarcely tinted residue will be left, 
which, when treated after cooling with a few drops of an alcoholic 
solution of potassium hydrate, will assume a violet color." — U. S. P. 

Hyoscyamine (C n H 23 N0 3 ) occurs in the leaves (Hyoscyamus, 
U. S. P.) and other parts of henbane, belladonna, stramonium, and 
various species of Scopola; also (Dymond) in lettuce. It forms 
brilliant colorless needles. Its salts also are crystalline. Its effect 
on the eye is similar to that of atropine. The researches of Laden- 
burg show that hyoscyamine is the tropate of an alkaloid isomeric 
with tropine. (See Atropine.) Ladenburg also finds in henbane 
some hyoscine. (See above.) The hyoscyamine hydrobromate is 
official (Hysocyamince Hydrobromas, U. S. P.). It is a yellowish- 
white, neutral, deliquescent, resin-like mass, either amorphous or 
crystalline. It is soluble in water and alcohol, but less so in ether 
and chloroform, and is not precipitated from its solution by platinic 
chloride. Gold chloride gives a precipitate which, on being recrys- 
tallized from a small quantity of boiling weak hydrochloric acid, 
deposits in lustrous golden-yellow scales (difference from atropine). 

Hyoscyamine sulphate, (C 17 H 23 N0 3 ) 2 ,H 2 S0 4 , is official (Hyoscya- 
■mince Sulphas, U. S. P.). It is yellowish-white. 

' The alkaloids which occur in Datura Stramonium, or thornapple 
(Folia et Semina Stramonii, U. S. P.), Dhatura (Datura alba; 
Datura Folia et Semina, P. I.), and in Duboisia Myoporoides, and 
were formerly supposed to be distinct alkaloids, called respectively 
daturine and duboisine, are identical with hyoscyamine, and the 
latter is isomeric with atropine (Ladenburg). Duboisine may, how- 
ever, be identical with hyoscine. Indeed, according to Schmidt, 



ALKALOIDS. 539 

the alkaloid of Duboisia myoporoides is sometimes hyoscyamine and 
sometimes hyoscine or scopolamine. Bees which sip from the 
flowers of stramonium are said to produce poisonous honey. 

Hyoscyamine melts when heated to between 108° and 109° C.,and 
then is soon converted into atropine. Its solutions in alcohol or 
ether are stable, but the presence of a very minute amount of fixed 
caustic alkali or a very little alkaline carbonate causes complete 
conversion of the hyoscyamine into atropine. With gold chloride 
its salts give a yellow crystalline precipitate. 

Jaborandine and Jaborine. — See Pilocarpine. 

Jervine (C 30 H 46 N 2 O 3 ) occurs in Veratrum album, white hellebore, 
and ( V. Viride, U. S. P.)* American white hellebore, the root of 
which is officially recognized in Great Britain {Veratri Viridis 
Rhizoma, B. P.). Its salts are much less soluble in water than those 
of veratrine. According to Bullock, Veratrum viride contains still 
another alkaloid, veratroidine, and, according to Mitchell, Veratrum 
album also contains an alkaloid which he terms veratralbi?ie. Tobien 
gives the formula of jervine as C 27 H 47 N 2 8 , and of veratroidine as 
C 51 H 78 N 2 16 or C 24 H 37 N"0 7 . According to Wright, Veratrum album 
contains jervine, C 26 H 37 N0 3 ; pseudo-jervine, C 29 H 43 N0 7 ; rubijervine, 
C 26 H 43 N0 3 ; veratralbine, C 28 H 43 N0 5 ; and traces of veratrine, 
C 37 H 63 NO n . The same author finds Veratrum viride to contain 
jervine, pseudojervine, cevadine, C 32 H 42 N0 9 , rubijervine, and traces 
of veratrine and veratralbine. Pehkschen finds jervine, C 14 H 22 N0 2 , 
pseudojervine, C 29 H 49 N0 12 , and veratroidine, C 32 H 53 N0 9 , while Salz- 
berger, besides jervine, rubijervine, and pseudojervine, finds proto- 
veratrine, C 32 H 51 NO n and protoveratradine, C 26 H 45 N0 8 . Salzberger 
confirms Wright and Luff's formula for jervine. 

Juglandine is the name given by Tanretto an alkaloidal substance 
obtained from the leaves of the walnut, Juglans regia. In the root- 
bark of Juglans cinerea, or butternut {Juglans, U. S. P.), Thiebaud 
found a bitter substance and an acid resembling chrysophanic. 

Lobeline. — A volatile fluid alkaloid first isolated from the dried 
flowering herb Lobelia injlata {Lobelia, B. P.) by Procter. In the 
pure state it is inodorous ; impure, it smells slightly of the plant, 
but mixed with ammonia it emits a strong and characteristic smell 
of the herb. With acids it forms salts. A solid alkaloid is said to 
be present also. 

Lupuline is stated by Greismayer to be a liquid volatile alkaloid 
contained in the hop, Humulus lupulus {Lupulus, B. P.). 

Nectandrine. — Vide Beberine. 

Nicotine, C 10 H 14 N 2 or {C & R 1 ) /// 2 N 2 , or hexahydrodipyridyl, C 10 H 8 - 
(H 6 )N 2 . — This also is a volatile liquid alkaloid, forming the powerful 
active principle of tobacco {Nicotiana Tabacum), malate and citrate 
of nicotine being the forms in which it occurs in the leaf {Tabacum, 
U. S. P.). Its odor is characteristic ; like conine, it yields a precipi- 
tate with gold perchloride ; but, unlike that alkaloid, its aqueous 

*The name Green Hellebore is sometimes applied to this drug, but 
properly belongs to Helleborus viridis (vide " Helleborin " in Index), which 
is medicinal in some parts of Europe (Hanbury). 



540 ORGANIC CHEMISTRY. 

solutions arc precipitated yellowish-white by platinum perchloride. 
It is not official. It is also contained in pituri, a drug " chewed by 
the natives of some parts of Australia as a stimulant narcotic," 
though, according to Liversedge, the latter alkaloid may have the 
formula C 12 H 16 N a . 

Phtsostigmine (C 15 H 21 N 8 2 ) (Physostigmina, B. P.). — An alkali 
obtained from the Calabar bean (Physostigma, U. S. P.), the seed of 
Physostigma venenosum (Jobst and Hesse), "by dissolving the alco- 
holic extract in water, filtering, adding sodium bicarbonate!, shaking 
the mixture with ether, and evaporating the ethereal liquid." it 
occurs " in colorless or pinkish crystals, slightly soluble in water, but 
readily soluble in alcohol and in diluted acids. The aqueous solution 
has an alkaline reaction, when warmed with or when shaken with 
dilute solution of potash becomes red, and when evaporated to dry- 
ness with ammonia over a water-bath leaves a bluish residue, the 
acidified solution of which is beautifully dichroic, being blue and 
red." — B. I\ A trace of it powerfully contracts the pupil of the eye 
[Lamellm Physostigmince, B. P.) ; a small quantity is highly poison- 
ous. Physostigmine Salicylate is official (P/tt/sostigmince Salicylas, 
U.S. P.), C 15 H 2l N 8 2 ,aiL6 8 . The sulphate is also official (Physo* 
stigmince Sulphas, U. S. P.), (Cj 5 H 21 N ;t 2 ) 2 \lI 2 S0 4 , It is a fine, odor- 
less white crystalline powder with a bitter taste, very soluble in 
water and alcohol. Fraser also isolated another (but, possibly, the 
same) principle from the bean, and termed it eserine, from esere, the 
name of this ordeal-poison at Calabar. Eber states that physostig- 
mine by action of acids, etc. takes up the elements of water, and 
becomes eseridine, C ]5 II 2 . t N.j0 3 , an alkaloid one-sixth the strength of 
physostigmine, and occurring to some extent in the Calabar bean 
itself. 

Pilocarpine is, apparently, the active principle of the diaphoretic 
and sialagogue jaborandi, the leaflets of Pilocarpus pennatifolius 
(Pilocarpiis, U. S. P.). The occurrence of an alkaloid in this plant 
was first announced by Hardy, followed almost immediately by 
Byasson. A crystalline nitrate and hydrochlorate were first obtained 
by Gerrard. The leaves also yield an essential oil, a terpene, C 10 H M 
(Hardy). Harnack and Meyer state that the true formula for pilo- 
carpine is C n H 1( .N 2 2 , and that its effects resemble those of nicotine, 
but that jaborandi yields another alkaloid, jaborine, which probably 
closely approaches pilocarpine in composition, though allied to 
atropine in effects. One salt is official in each of* the Pharmacopoeias, 
the nitrate {Pilocarpines Nitras, B. P.), C 41 H 16 N 2 2 ,HN0 3 , and pilo- 
carpine hydrochlorate [Pilocarpinai Hydrochloras, n Il 1( .N 2 O./IICI, 
U.S. I'.). This alkaloid is obtained from extract of jaborandi by 
shaking it with chloroform and a little alkali, and evaporating the 
chloroformic solution. The product, neutralized by nitric acid and 
purified by rccrystallization, yields the nitrate as a white granular 
powder or as prismatic crystals. It has a faintly bitter taste, and 
is soluble in water and in rectified spirit. Strong sulphuric acid 
forms with it a yellowish solution which, on the addition of red 
potassium chromate, gradually acquires an emerald-green color, ft 



ALKALOIDS. 541 

leaves no ash when burned with free access of air. It causes con- 
traction of the pupil of the eye. Merck states that a third alkaloid, 
pilocarpidine, C 10 H u N 2 O 2 , is present in jaborandi. Harnack thinks 
that pilocarpine is probably a methyl derivative of pilocarpidine. 
The suggestion also is offered that the formula for nicotine differing 
only by 2 from pilocarpidine, the latter is perhaps only dihydroxyl- 
nicotine. According to Merck, confirmed by Hardy and Calmels, 
jaborine is derived from pilocarpine by natural oxidation, while 
pilocarpidine similarly yields jaboridine, C 10 H 12 N 2 O 3 . The latter 
chemists have obtained pilocarpine artificially, " /3-pyridine a-lactic 
acid " being converted into pilocarpidine, and this into pilocarpine. 

Piperine [Piperinum, U.S. P.) (C 17 H 19 N0 3 ) is a feeble alkaloid 
occurring in White, Black (Piper, U. S. P.), Long Pepper (Chavica 
officinarum, Mign.), and Cubeb Pepper (Cubeba, U. S. P.), associated 
with volatile oil and resin ; to these three substances the odor, flavor, 
and acridity belong. Piperine is obtained on boiling white pepper 
with alcohol, and evaporating the liquid with solution of potash, 
which retains resin. Recrystallized from alcohol, piperine forms 
colorless prisms fusible at 212° F. With acids and certain metallic 
compounds it forms salts, and distilled with strong alkali yields 
piperidine or piperidia (C 5 H 10 HN), an alkaloid of strong chemical 
properties, andpiperic acid (C 12 H 10 O 4 ). Piperidine is interesting as 
being one of the alkaloids that has been obtained artificially by 
Ladenburg. It is hexa-hydro-pyridine, and is obtained by the action 
of nascent hydrogen on pyridine. Johnstone finds it in long pepper 
and in ordinary pepper, more especially in the husk. According to 
Buchheim, the amorphous resin of the peppers is similar in consti- 
tution to piperine, alkalies breaking it up into piperidine and chavicic 
acid. Pyrethrin is also said to be a member of the series. The 
piperine of cubeb pepper is not to be confounded with cubebin, a 
neutral constituent and having the formula C 10 H 10 O 3 — a derivative, 
probably, of pyrocatechin. 

Sanguinarine is the alkaloid of blood-root (Sanguinaria Canaden- 
sis). Its salts are red. Konig and Tietz find five distinct alkaloids 
in the root of sanguinaria — viz. chelerythrine, C 21 H 17 N0 4 ; sangui- 
narine, C 20 H 15 NO 4 ; a-homochelidonine, C 21 H 21 N0 5 ; J3-homochelidonine, 
C 21 H 21 N0 5 ; and protopine, C 20 H n NO 5 . Protopine was found in opium 
by Hesse (who assigned it the formula C 20 H 19 NO 5 ). It also occurs in 
Celandine Chelidonium, U. S. P., p. 534, and probably is identical 
with macleyine, obtained by Eyckmann from Macleya cor data. 

Solanine, (C 43 H 69 N0 16 ). — An alkaloid existing in the woody night- 
shade or bitter-sweet (Solanum dulcamara). The dried young 
branches of the plant are official (Dulcamara, U. S. P.). It occurs 
also in the shoots and in minute amount in the skins of the tubers 
of the potato [Solanum tuberosum). This alkaloid is only slightly 
soluble in water, alcohol, or ether ; nitric acid colors it yellow ; sul- 
phuric acid produces at first a yellow, then a violet, and finally a 
brown coloration. It is said to be a conjugated compound of sugar 
with solanidine (C 25 H 39 NO). Geissler finds dulcamarin (C 22 H 34 O 10 ), 
a glucoside, to be the bitter constituent of Solanum dulcamara. A 
mixture of sulphuric acid and alcohol, or either selenic acid or 
24 



542 ORGANIC CHEMISTRY. 

sodium selenate and sulphuric acid, colors solanine or solanidine a 
dark red. 

Sparteine (C 15 H 26 N 2 ) is a poisonous volatile alkaloid' occurring 
in broom-tops (Scoparius, U. S. P.). Its discoverer, Stenhouse, 
considers that the diuretic principle of broom is scoparin, a non- 
poisonous body, sparingly soluble in cold water. Mills has obtained 
ethyl-sparteine (C 15 H 25 C 2 H 5 N 2 ) and diethyl-sparteine (C 15 H 24 C 2 H 5 - 
C 2 H 5 N 2 ). Apparently sparteine contains two pyridine nuclei. The 
sulphate is official, Sparteince Sulphas, U. S. P. (C 15 H 26 N 2 ,H 2 S0 4 ,- 
4H 2 0). It is a colorless crystalline or granular powder, devoid of 
smell, but having a bitter taste, soluble in water and alcohol. At a 
temperature of 83°-100° C. the salt loses its water of crystallization, 
and on heating more strongly is finally burnt completely away. 
" 25 cc. of ether added to about 0.1 grm. of sparteine sulphate in a 
test-tube, then a few drops of dilute ammonia, so that the latter 
shall not be in excess, and an ethereal solution of iodine (1 in 50) 
afterward added until the liquid, when shaken, turns from an 
orange to a dark reddish-brown color ; the bottom and sides of the 
test-tube will after a short time be found coated with minute, dark 
greenish-brown crystals, distinctly seen with a lens after the liquid 
has been poured out." — U. S. P. A very small quantity of the salt 
added to a few drops of sodium hydrate solution and gently warmed 
should give no smell of ammonia (absence of ammonium compounds). 

Spigelina. — According to Dudley,, this is a volatile alkaloid and 
active principle of Spigelia marilandica, or pink-root (Spigelia, 
U. S. P.), a vermifuge and depressant. 

Stillingine. — Bichy states that this alkaloid is present in Still- 
ingia sylvatica or queen's root. 

Taxine, C 37 H 52 O 10 N ? is an alkaloid occurring in the yew. 

Theine, or Caffeine, or Guaranine (methyl-theobromine) 
(C 8 H 10 N 4 O 2 ,H 2 O).— This alkaloid (Caffema, U. S. P.) occurs in tea, 2 
to 4 J per cent. ; coffee, 1.2 per cent. ; mate or Paraguay tea, .2 to 2 
per cent. ; guarana ( Guarana, U. S. P.), " a dried paste chiefly con- 
sisting of the crushed or pounded seeds of Paullinia Cupana, Kunth 
{Pautiinia sorbilis, Martius)," 5 per cent. ; and the kola-nut. Infu- 
sions and preparations of these vegetable products are used, chiefly 
as beverages, by three-fourths of the human race. It is remarkable 
that the instinct of man, even in his savage state, should have led 
him to select as the bases of common beverages just the four or five 
plants which out of many thousands are the only ones, so far as we 
know, containing theine. 

Theine is volatile. Considerable quantities may be collected by 
condensing the vapors evolved during the roasting of coffee on the 
large scale. The infusion of tea from which astringent and color- 
ing matters have been precipitated by solution of lead subacetate, 
and which has been evaporated to a small bulk, yields a precipitate 
of theine on the addition of a strong solution of potassium carbonate. 
It may be crystallized from alcohol or by sublimation. Theine 
forms salts with acids. With citric acid caffeine forms the so-called 
citrated caffeine [Caff etna Citrata, U. S. P.), C 8 H 10 N 4 O 2 ,H 3 C 6 H 5 O 7 , 
which, in the dry state, is a citrate of the alkaloid, but on the addi- 



ALKALOIDS. 543 

tion of water is immediately decomposed. The citrate is a white, 
odorless powder with an acid taste and reaction, soluble in two volumes 
of chloroform and one volume of alcohol. It is used in the prepara- 
tion of Caffeina Citrata Effervescens, U. S. P. 

Tests. — Concentrated nitric acid, or, better, a mixture of potassium 
chlorate and hydrochloric acid, rapidly oxidizes theine, forming 
compounds which with ammonia yield a beautiful purple-red color, 
resembling the murexid obtained under similar circumstances from 
uric acid ; the oxidation must not be carried too far. Theine boiled 
with caustic potash yields methylamine (CH 3 HHN), the vapor of 
which has a peculiar characteristic odor. 

The chemical action of theine on the system is not yet quite made 
out. It is probably a pure stimulant. 

Theobromine, C 7 H 8 N 4 2 , is an alkaloid occurring in cocoa, the 
seed of Theobroma Cacao, to the extent of 1 to 2 per cent. Accord- 
ing to Schmidt, a little theine is present also. Theobromine is also 
present in kola-nut (Heckel and Schlagdenhauffen). The theine 
in cacao and kola, and probably in tea, is said to occur normally as 
a glucoside, which would explain why it is only partially extracted 
by chloroform from a mixture of tea, etc. and lime. 

Relations between Theine and Theobromine. — Both theine and 
theobromine are methyl derivatives of xanthine, C 5 H 4 N 4 2 (belong- 
ing to the uric-acid group, uric acid having the formula C 5 H 4 N 4 3 ). 
Theobromine, or dimethylxanthine (? the "theophylline" found in 
tea by Kossel), may be obtained from a compound of xanthine and 
silver by the action of methyl iodide, and theine (methyltheobromine 
or trimethylxanthine) may be obtained by heating theobromine- 
silver with methyl iodide (Strecker). 

Trigonelline, C 7 H 7 N0 2 H 2 0. — Jahns states that this alkaloid, as 
well as one identical with choline, is present in the seeds of 
fcenugreek or fenugreek (Trigonella Fcenum-gr cecum), much used in 
veterinary medicine and in some varieties of cattle-food and curry- 
powder. 

Veratrine, or Veratria (C 32 H 50 NO 9 , Schmidt and Kb'ppen ; 
C 52 H 86 N 2 ]5 , Weigelin) ( Veratrina, U. S. P.).— This alkaloid occurs 
in Cevadilla (Sabadilla, B. P., the seeds of Schcenocaulon officinale 
of A. Gray, termed Asagroza officinalis by Lindley and Veratrum 
officinale by Schlecht). It is also said to occur in the leaves of 
Sarracenia purpurea. According to Weigelin, cevadilla contains 
two isomeric varieties of veratrine, the one soluble, the other insolu- 
ble, in water. He says there are also present sabadilline (C 41 H 6 pN 2 13 ) 
and sabatrine (C 51 H 86 N 2 17 ). The veratrine of trade contains the 
two latter alkaloids (Weigelin). A mere trace of veratrine brought 
into contact with the mucous membrane of the nose causes violent 
fits of sneezing. These alkaloids, and those from the different 
species of Veratrum, are ^evidently very closely allied. Wright and 
Luff, by the use of tartaric acid, a solvent less likely than the 
stronger acids to decompose alkaloids, extract from cevadilla vera- 
trine, C 37 H 53 NO n ; cevadine, C 32 H 49 N0 9 ; and cevadilline, C 34 H 53 N0 8 . 
According to Merck, cevadilla contains two alkaloids — sabadine, 
C 29 H 51 N0 8 , and sabadinine, C 27 H 46 N0 8 . 



544 , ORGANIC CHEMISTRY. 

The British official process for the preparation of the alkaloid con- 
sists in exhausting the disintegrated cevadilla-seeds by alcohol, 
recovering most of the spirit by distillation, pouring the residue 
into water, by which much resin is precipitated, filtering, and preci- 
pitating the veratrine from the aqueous solution by ammonia. It is 
purified by washing with water, solution in dilute hydrochloric acid, 
decolorization of the liquid by animal charcoal, reprecipitation by 
ammonia, washing, and drying. The U. S. P. (1870) process is 
similar, but includes treatment of the first crude veratrine by diluted 
sulphuric acid and precipitation of alkaloid by magnesia. Bosetti 
states that it is a mixture of crystalline cevadine, insoluble in water, 
with an amorphous isomeric soluble alkaloid, veratridine. Accord- 
ing to Lissauer, their physiological action is identical. 

Unguentum Veratrince, U. S. P., contains 4 per cent, of the alka- 
loid. The veratrine is rubbed in a mortar, with 6 per cent, of olive 
oil and 90 per cent, of benzoated lard gradually added and thor- 
oughly mixed. 



QUESTIONS AND EXERCISES. 

How is aconitine prepared? — Give the strength of the official prepara- 
tions of atropine. — Describe the properties of atropine. — What is the 
active principle of stramonium ? — Mention official substances containing 
beberine and berberine.— Give the characters of beberine. — In what does 
nectandrine differ from beberine? — Mention the characteristics of conine. 
— What is the active principle of ipecacuanha ? — Name the alkaloid of 
tobacco. — Give the properties of the alkaloid of Calabar bean. — What are 
the sources of piperine? — Whence is theine obtained? what is its relation 
to theobromine? — Describe the preparation of veratrine. — State the 
properties of veratrine. 



Here the student is recommended to qualitatively analyze 
unnamed specimens (previously selected for him) op the free 
and combined organic substances included in the appended 
tables 1 and 2. 



PROXIMATE CONSTITUENTS OF ANIMAL ORGANISMS. 

Proteid Principles, or Albumenoids. 



Albumen. — Agitate, thoroughly, white of egg ( Ovi Albumen, 
B. P.) with water, and strain off the liquid from the flocculent 
membranous insoluble matter. One white of egg in 180 cc. of 
water forms the " Albumen Test-solution," U. S. P. 

Test. — Heat a portion of this solution of albumen to the 



L ALKALOIDS, GLYCOSIDES, ETC. 

[.) 
a drop of Mayer's solution (mercuric iodide and potassium 



r glucosides, etc. 

• 

y so. tlien — 

chloride and by sodium bicarbonate and chloroform. 

on of stannous chloride. 

chloride and other tests. 

iric acid and ferric chloride. 



iig with strong hydrochloric acid, which gives a reddish- 

on. 
fcion. 

ioquin, etc. 

test, etc. 



1 tingling. 

d — red precipitate. 



\y acidified with hydrochloric acid and cooled— crystalline 
iporation to dryness: the residue dissolved in acid gives a 



rile or phenyl-earbaniine, CkHoXC. 
scarlet, 

alcohol, partly in ether. Acrid taste. 

;ep red. 

uted sulphuric acid = deep green. 

d. 

►ride with an equal volume of strong sulphuric acid gives a 

chloric acid, and ferric chloride = deep red (Fe26CNS). 
ities of the substance. 

?ye is involved should be made with extremely dilute solu- 
to 1 pint of water. If no effect is produced in an hour, it is 
) one of twice the latter strength, and so on. The chief 
bracting agents (myotics) are physostigmine and pilocarpine. 



following memoranda 



Dissolved in strong sulphuric acid, with addition of a few 
or red color, which is changed to deep claret on addition of 

[png sulphuric acid gives red-brown color. 

id precipitated by acids. Taste slightly bitter. 



TABLE TO All. IN' THE IDENTIFICATION OF OFFICIAL ALKALOIDS, GLUCOSIDES, ETC. 

(Compiled by F. W. Short.) 
, i„ a few drops of water or dilute Hy.!,-...-!.!,..!.- and. and a.l.l a rtrop of Mayer's solution (mercuric iodide and potassi, 






inrhlorie arid, which ^ives ;i nrldish- 






•ocliloric acid and cooled— crystalline 



PllYSOStiuniine . Warmed wiih |i"i:.sli i:n.- i.<l r<.lm\ whirli lu-mmcs Unish on « \»p<>i :•. 1 1. -n i.> dr\n<--s; the residue dissolved in acid giv 



B. If tl.esul.Mann 



■id. with addition of a few 



ic rts. Taste slighl 



binary Scale Compounds. 



(generally converted into pyrophosphoric) 
i contamination). 



y of the scale. Heat the ash with nitric 
ess of solution of ammonium niolybdate in 



No Yellow Precipitate. 



Precipitate some of the aqueous 
solution with potash, filter, and add 
to a portion of the filtrate a slight 
excess of nitric acid, divide into two 
parts. To one add barium chloride 
(ppt. = sulphuric acid). To the other 
add silver nitrate (ppt. = hydrochloric 
acid). Neutralize another portion of 
the potash filtrate with nitric acid 
and add silver nitrate. 



Precipitate 
Gray to Black. 



Add very little 
ammonia (not suf- 
ficient to dissolve 
the whole precip- 
itate) and heat. 
A silver mirror = 
tartaric acid. 

Calcium chlo- 
ride and lime ppt. 
a neutral solution 
(if concentrated) 
in the cold, the 
precip. redissolv- 
ing on boiling. 



Precipitate 
White. 

Citric acid gives 
imperfect or no 
mirror. Calcium 
chloride and lime 
do not precipitate 
citric acid in the 
cold, but upon 
boiling (if solu- 
tion be sufficient- 
ly concentrated) 
precipitation oc- 
curs. 






f Ammonium (often as 

a contamination). 
-J Ferric Salt. 
| Potassium. 
[ Sodium. 



Ammonium. — Boil aqueous 
solution of scale with potash 
and test vapor for ammonia. 
Filter and dissolve precipi- 
tate in hydrochloric acid, 
and test the solution for 
iron by ferrocyanide, sul- 
phocyanate, etc. 

Potassium and Sodium. — 
Ignite a small quantity of 
the scale, and moisten the 
residue with water. Test 
moistened residue with lit- 
mus-paper. If alkaline, ex- 
amine for potassium and 
sodium by the color im- 
parted to flame, and for 
potassium by the platinum 
test. 



Confirm Tartaric or Citric Acid. — To slightly acidified potash filtrate 
add ammonia in slight excess and considerable quantity of ammo- 
nium and calcium chlorides. Tartrates are precipitated completely 
in the cold with agitation and rest for about ten minutes. To the 
solution (or filtrate, if tartrates are present) add three volumes of 
spirit of wine, when citrates are precipitated. If sulphates have 
been found, disregard a slight precipitate with spirit of wine. 



Compiled hy A. Senier. 



,-f. Analysis OF ORDINARY SCALE COMPOUNDS. 

i I.U'euer.tlly eonviitril int.. pvinphospliuriLi. 



Ammoxium (often a 

:l cnlltulniliiitiou). 

Fekkic salt. 

Potassium. 

Sodium. 



DIhmiIvi' .1 i '"" "' «;'!• i'. "ii. I m.IiI 

iilkuluiiU (excepl slr.vrliiiinrl iiml wiiiiHr 
mixture ivilli :i lillle ether, nii.l xep 
,i,]nii"i | nollili mil in* 



E IEA1 ! "i 

JTaj contnh in 

bobo I- oliilii 



GllEKN 

lllllllle 


iquln) 


Bolutloi 


is am 


■ii li.-i-' ',| 




.1 Hi,- „ 





ll I prarliitlnli 

■/'">" ... . nol ,, 

Jlno, 

Ptoothoi iimiIim.i 
"liiu-'i'. 1 !. 




Kht preeipitate witli_ spirit o'f wine. 

Compiled ty A. Skxikr. 



545 

boiling-point; the albumen becomes insoluble, separating in 
clots or coagula of characteristic appearance. 

Other Reactions. — Add to small quantities of aqueous solu- 
tion of albumen solutions of corrosive sublimate, silver nitrate, 
copper sulphate, lead acetate, alum, stannic chloride ; the vari- 
ous salts not only coagulate, but form insoluble compounds 
with albumen. Hence the value of an egg as a temporary 
antidote in cases of poisoning by many metallic salts, its ad- 
ministration retarding the absorption of the poison until the 
stomach-pump or other means can be applied. Sulphuric, 
nitric, and hydrochloric acids precipitate albumen ; the coag- 
ulum is slowly redissolved by aid of heat, a brown, yellow, or 
purplish-red color being produced. Neither acetic, tartaric, nor 
organic acids generally, except picric and gallotannic, coagulate 
albumen. Alkalies prevent the precipitation of albumen. 

Yolk or Yelk of Egg ( Vitellus, U. S. P.) contains only 3 per cent, 
of albumen, the white 12£. The yolk also contains 30 per cent, of 
yellow fat and 14 of casein, with what is stated to be another proteid, 
vitellin. 

Albumen is met with in large quantity in the serum of blood, in 
smaller quantity in chyle and lymph, and in the brain, kidneys, 
liver, muscles, and pancreas. It is not a normal constituent of 
saliva, gastric juice, bile, or mucus, but may occur during inflamma- 
tion. It is found in the urine and faeces only under certain diseased 
states of the system. 

The cause of the coagulation of albumen by heat has not yet been 
discovered. 

Albumen has never been obtained sufficiently pure to admit of its 
composition being expressed by a trustworthy formula ; Gerhardt 
regarded it as a sodium compound (HNaC 72 H 110 N 18 SO 22 ,H 2 O). 

Egg-albumen — and, to some extent, blood-albumen — is largely 
used by calico-printers as a vehicle for colors, serving also, when 
dry, as a glaze. Curriers prize egg oil for softening leather. 

Albumen coagulated by heat is said to be recoverable in a scarcely 
altered fluid condition by contact with a dilute aqueous solution of 
a very small proportion of pepsin. 

Fibrin, Casein, Legumin. 

Fibrin is the chief constituent of muscular tissue. It occurs in 
the blood in the form of a very unstable compound termed fibrin- 
ogen, and its liberation from this union and spontaneous solidifica- 
tion or coagulation is the cause of the clotting of blood shortly after 
being drawn from the body. The latter phenomenon cannot at 
present be explained satisfactorily. Fibrin may be obtained by 
whipping fresh blood with a bundle of twigs, separating the adherent 
fibres, and washing in water till colorless. It may be kept either 
dry or in spirit of wine. 



rv, & 

s 



O «2 



1.4 



546 ORGANIC CHEMISTRY. 

Average Composition of Blood {in 1000 parts) {compiled by Kirkes). 

Water 784 

Albumen 70 

Fibrin 2.2 

Red corpuscles (globulin, 123 ; hsematin, 7) . 130 

fCholesterin 0.08^ 

ri I Cerebrin 0.40 

JTI ) Serolin ...... . , 0.02 

Oleic and margaric acids 

Volatile and odorous fatty acid . . . 

Fat containing phosphorus ..... 

Sodium chloride = 3.6 

Potassium chloride .35 

Sodium phosphate (Na 3 P0 4 ) .2 

Sodium carbonate .... .82 

Sodium sulphate .28 

Calcium and magnesium phosphates .... .25 

^Iron oxide and phosphate .50 

Extractive matters, biliary coloring-matter, 

gases, and accidental substances . . . 6.4 



1000.0 



Percentage Proportion of the Chief Constituents of Blood. 

Water ' 78.4 

Red corpuscles (solid residue) . 13.0 

Albumen of serum 7.0 

Inorganic salts .6 

Extractive, fatty, and other matters .8 

Fibrin 2 



100.0 



Casein occurs in cow's milk {Lac, B. P.) to the extent of about 
4 per cent., dissolved by a trace of alkaline salt. Its solution does 
not spontaneously coagulate, like that of fibrin, nor by heat like 
albumen, but acids cause its precipitation from milk in the form of 
a curd (cheese) containing the fat- (butter-) globules previously sus- 
pended in the milk, a clear yellow liquid (or whey) remaining. 
Curds and whey are also produced on adding to milk a piece or an in- 
fusion of rennet, the salted and dried inner membrane of the fourth 
stomach of the calf. The exact action of rennet is not known, but 
it seems to be due to the presence of a milk-curdling ferment which 
is not an acid and not pepsin, and which appears also to occur in 
the pancreatic juice, the intestinal juice, and some vegetable juices. 
Respecting rennet Soxhlet says : "60 to 80 grammes of calf's 
stomach, steeped for five days in 1 litre of a 5 per cent, solution 
of common salt at ordinary temperatures, yield a solution of which 
one volume will coagulate ten thousand volumes of new milk at a 
temperature of 95° F. in forty minutes. If the filtered solution is 



MILK. 



547 



treated with 60 to 90 grms. more of stomach, a solution of double 
strength is obtained ; another repetition gives a solution three times 
the strength of the original one. To prevent decomposition, about 
0.3 per cent, of thymol may be added to the concentrated rennet- 
extract solution. Possibly a slight taste due to this may be detected 
in the finest cheese, but for the same reason oil of cloves is much 
more objectionable. Boric acid is on all accounts the best anti- 
septic to employ, and solutions to which it has been added may be 
kept in covered vessels for months. All extract solutions lose 
strength on keeping ; daring the first two months the solution 
may become 30 per cent, weaker, then the strength remains nearly 
constant for eight months in the case of a solution of 1 in 18,000. 
Alcohol is almost as good an antiseptic as boric acid if the solution 
be preserved in well-stoppered flasks." 

Average Composition of 1000 Parts of Milk. 





Specific gravity. 


Water. 


Solid 
con- 
stitu- 
ents. 


Casein 
and 

extrac- 
tive. 


Sugar. 


Butter. 


Salts. 


Woman . . 
Cow .... 


1.030 to 1.034 
1.030 to 1.035 


870 

877 


130 
123 


27 
40 


60 
46 


40 
30 


3 

7 



Leeds puts the average composition of human milk at 2 per cent, 
of albumenoids, 7 per cent, of milk-sugar, 4 per cent, of fat, and 0.2 
per cent, of ash. 

Specific gravity alone, as taken by the form of hydrometer termed 
a lactometer or even by more delicate means, is of little value as an 
indication of the richness of milk, the butter and the other solids 
exerting an influence in opposite directions. Good cow's milk 
affords from 10 to 12 per cent, by volume of cream and 3 to 3 J per 
cent, of butter. The water of milk seldom varies more than from 
87 to 88 per cent., and the solid constituents from 13 to 12. Indeed, 
excluding its butter, milk is curiously regular in composition. The 
non-fatty solids in the mixed milk of a herd or dairy of healthy 
cows is almost a constant quantity — namely, 9.3 per cent. A lower 
proportion of non-fatty solids in a sample of milk points to the 
addition of water. Thus, supposing that 100 grains of a specimen 
of milk evaporated to dryness, and all butter extracted from the 
residue (previously disintegrated by help of 1 or 2 parts of dried 
gypsum or the dried infusorial earth termed KieselguJir) by 
ether (or placed on blotting-paper and dried and exhausted 
by ether — Adams), yielded a non-fatty residue of 7.44 grains, 
the specimen would probably be four-fifths milk and one-fifth 
water.* For if 9.3 indicate 100, then 7.44 indicate 80. Ocea- 

* Soxhlet determines fat by noting the specific gravity of an ethereal 
solution, and then referring to tables showing percentage of fat in ethereal 
solutions of varying specific gravity. *._ 



548 ORGANIC CHEMISTRY. 

sionally, under exceptional circumstances, a sample of genuine 
milk might be slightly poorer than that from a healthy herd, and 
therefore, for legal purposes, a standard of 9 per cent, by weight 
of non-fatty solids and 2.5 per cent, of butter-fat has been proposed. 
Only in the rare cases of milk containing an unusually large pro- 
portion of butter-fat would any milk yielding less than 9 per cent, 
of non-fatty solids be regarded as genuine. And, again, no milk 
would be considered genuine, under this standard, if it yielded 
less than 2.5 per cent, of fat, not even in the rare case of its con- 
taining an unusually large proportion of real non-fatty milk-solids. 
Half-starved cows might yield milk below these standards, but it 
could scarcely be considered to be normal or better fitted for food 
than milk watered after leaving the cow. If, however, such milk 
is to be regarded as genuine, the standard of 8.5 of non-fatty solids 
will not be too low. 

Ewe's milk is much richer than either human or cow's milk. 

Under the microscope milk is seen to consist of minute corpuscles 
floating in a transparent medium. These corpuscles consist of the 
fatty matter (butter) said to be contained in a filmy albumenoid 
envelope. The fat is fluid at the normal temperature of the animal, 
and remains so until the milk is well agitated by churning or other- 
wise or until the milk is frozen. 

Legumin, or vegetable casein, is found in most leguminous seeds 
and in sweet and bitter almonds. Peas contain about 25 per cent, 
of legumin. 

Vegetable albumen is contained in many plant-juices, and is 
deposited in flocculi on heating such liquids. Vegetable [fibrin is 
the name given by Liebig and Dumas to that portion of the gluten 
of wheat which is insoluble in alcohol and ether. Spongine, the 
organic matter of sponge, appears to be a proteid. 

Albumenoid substances are nearly identical in percentage compo- 
sition. Albumen and fibrin contain 53.5 of carbon, 7 of hydrogen, 
15.5 of nitrogen, 22 of oxygen, 1.6 of sulphur, and 4 of phosphorus. 
Casein contains no phosphorus. These three bodies Liebig termed 
the plastic elements of nutrition, under the assumption that animals 
directly assimilate them in forming muscles, nerves, and other 
tissues — starch, sugar, and similar matter forming the respiratory 
materials of food, because more immediately concerned in keeping 
up the temperature of the body by the combustion going on between 
them and their products and the oxygen of the air in the blood ; 
but the classes are scarcely so well differentiated as the terms would 
imply. 

The whole of the organic nitrogen in food must not, moreover, 
be regarded as representing true albumenoids, some existing as 
amidic and similar compounds — bodies having a simplicity of com- 
position characteristic of the products of physiological action on food, 
rather than that complexity of composition characteristic of true 
nutrients. Albumenoids in decomposing yield much fatty matter 
as well as other substances. Possiby a portion, at least, of the 
adipocere (adeps, fat ; cera, wax), or corpse-fat, characteristic of the 
remains of buried animals, is thus derived. 



GELATIGENOUS SUBSTANCES. 549 

Albumenoids are divided, according to their solubility in water 
and certain saline solutions such as ammonium sulphate, into 
"albumens 1 ' or "albumins," "globulins," " albumoses," "pep- 
tones," etc. To the second of these classes the poisons of most 
venomous snakes probably belong, and a globulin and an albu- 
mose, each harmless when swallowed, but extremely poisonous 
when injected into the blood, occur in the seeds of Abrus preca- 
torius (jequirity). 

Musk (Moschus, U. S. P.), "the dried secretion from the preputial 
follicles of Moschus moschiferus " (the musk deer), is a mixture of 
albumenoid, fatty, and other animal matters with a volatile odorous 
substance of unknown composition. " Artificial musk," a syntheti- 
cal compound having an odor resembling in quality and power that 
of natural musk, is trinitro-isobutyl-toluene, 6 HCH3,C(CH 3 ) 3 (NO 2 ) 3 . 

Gelatigenous Substances. 

These nitrogenous bodies differ, chemically, from the albumenoid 
in containing less carbon and sulphur and more nitrogen. They 
are contained in certain animal tissues, and on boiling with water 
yield a solution which has the remarkable property of solidifying 
to a jelly on cooling. The tendons, ligaments, bones, skin, and 
serous membranes afford gelatin proper ; the cartilages give chon- 
d?'ine, which differs from gelatin in composition and in being pre- 
cipitated by vegetable acids, alum, and lead acetates. The purest 
source of gelatin is isinglass (B. P.) (Ichthyocolla, U. S. P.), "the 
swimming-bladder or sound of various species of Acipenser, Linn., 
prepared and cut in fine shreds." Small quantities are more easily 
disintegrated by a file than a knife. 50 grains dissolved in 5 ounces 
of distilled water forms the official " Solution of Isinglass," B. P. 
Gelatin (Gelatinum, B. P.) is officially defined as ■" the air-dried 
product of the action of boiling water on gelatigenous animal tissues, 
such as skin, tendons, ligaments, and bones." Glue is an impure 
variety of gelatin made from the trimmings of hides ; size is glue 
of inferior tenacity prepared from the parings of parchment and 
thin skins. " Among the varieties of gelatin derived from different 
tissues, and from the same sources at different ages, much diversity 
exists as to the firmness and other characters of the solid formed on 
the cooling of the solutions. The differences between isinglass, size, 
and glue in this respect are familiarly known, and afford good exam- 
ples of the varieties called weak and strong or low and high gelatins. 
The differences are sometimes ascribed to the quantities of water 
combined in each case with the pure or anhydrous gelatin, part of 
which water seems to be intimately united with the gelatin ; for no 
artificial addition of water to glue would give it the character of 
size, nor would any abstraction of water from isinglass or size con- 
vert it into the hard, dry substance of glue. But such a change is 
effected in the gradual process of nutrition of the tissues ; for, as a 
general rule, the tissues of an old animal yield a much firmer or 
stronger jelly than the corresponding parts of a young animal of the 
same species " (Kirke's Physiology). 
24* 



550 ORGANIC CHEMISTRY. 

Gelatin is supposed by some to be a glucoside, yielding an ammo- 
nium salt when boiled with diluted acids. It appears to unite 
chemically with a portion of the water in which it is soaked when 
used for culinary or manufacturing purposes, for a solution of glue 
in hot anhydrous glycerin does not yield an ordinary jelly on cool- 
ing. From its solution in water gelatin is precipitated by alcohol, 
corrosive sublimate, platinum perchloride, and by tannic acid. Its 
aqueous solution is not, like that of albumen, coagulated by heat, 
nor is it precipitated by acids. By prolonged ebullition its gelat- 
inizing power is destroyed. 

Pepsin. 

Pepsin (from tt^ttto), pepto, I digest) is a nitrogenous substance 
existing in the gastric juice and as a viscid matter in the peptic 
glands and on the walls of the stomachs of animals. It appears to 
be a modification of a precursor termed pro-pepsin, stomachs not 
yielding so much pepsin when quite fresh as after twenty -four hours. 
To isolate pepsin, the cleansed mucous membrane of the stomach 
(of the hog, sheep, or calf, killed fasting) is scraped, and macerated, 
with the scrapings, in cold water for twelve hours ; the pepsin in 
the strained liquid is then precipitated by lead acetate, the deposit 
washed once or twice by decantation, sulphuretted hydrogen passed 
through the mixture of the deposit with a little water to remove the 
whole of the lead, and the filtered liquid evaporated to dryness at a 
temperature not exceeding 105° F. Pepsin is a powerful- promoter 
of digestion ; its solution is hence frequently termed artificial gastric 
juice. As met with in pharmacy its strength varies greatly. It is 
often prepared by simply mixing with starch the thick liquid ob- 
tained on macerating the scraped stomach with water, and evap- 
orating to dryness. ( Vide Pharmaceutical Journal, 1865-66, p. 
112, and 1871-72, pp. 785 and 843.) The official B. P. process sim- 
ply consists in scraping the viscid pulp from the slightly washed 
inner surface of the stomach, and quickly evaporating it to dryness 
on glass or glazed earthenware at a temperature not exceeding 100° 
P. The product is powdered. 

Official pepsin (Pepsinum, U. S. P.) is a yellowish-white to light- 
brown amorphous powder, sometimes in the form of scales, having 
a faint but not disagreeable odor, and a slightly saline taste, with- 
out any indications of putrescence, being somewhat hygroscopic and 
insoluble in alcohol, ether, and chloroform. 

Valuation of Pepsin. — To 93 cc. of water add almost 2 cc. of 
dilute hydrochloric acid, and, having brought it to a temperature 
of 104° F. (40° C), add 5 cc. of a solution of pepsin (obtained by- 
dissolving 0.067 grm. of pepsin in 98 cc. of water and nearly 2 cc. 
of dilute hydrochloric acid) ; the resulting liquid will contain 0.2 
cc. (0.21 grm.) of absolute hydrochloric acid, 0.00335 grm. of the 
pepsin to be tested, and 98 cc. of water. 

"Immerse and keep a fresh hen's egg during fifteen minutes in 
boiling water ; then remove it and place it into cold water. When 
it is cold separate the white, coagulated albumen, and rub it through 



PANCEEATIN. 551 

a clean sieve having thirty meshes to the linear inch. Reject the 
first portion passing through the sieve. Weigh off 10 grms. of the 
second, cleaner portion, place it in a flask of the capacity of about 
200 cc, then, add one-half of solution, and shake well, so as to dis- 
tribute the coherent albumen evenly throughout the liquid. Then 
add the second half of solution, and shake again, guarding against 
loss. Place the flask in a water-bath or thermostat kept at a tem- 
perature of 38° to 40° C. (100.4° to 104° F.) for six hours, and shake 
it gently every fifteen minutes. At the expiration of this time the 
albumen should have disappeared, leaving at most only a few thin, 
insoluble flakes. (Trustworthy results, particularly in comparative 
trials, will be obtained only if the temperature be strictly main- 
tained between the prescribed limits, and if the contents of the flasks 
be agitated uniformly and in equal intervals of time.)'' — U. S. P. 

The solvent or digestive action of pepsin on the albumenoids, etc. 
in the stomach results in a nutritive and digestive fluid termed pep- 
tone, forming a portion of the whole product of stomach-digestion, 
or chyme. It is thus that such food is prepared for conversion into 
blood. Artificial or alimentary peptone may be made by digesting 
blood-fibrin with pepsin in very weak hydrochloric acid. Clermont 
prepares alimentary peptone in solution by heating 40 parts of 
minced meat with 30 of water and 1 of sulphuric acid in a sealed 
tube, filtering, and evaporating the resulting fluid to dryness, and 
treating the residue with water. The solution is not precipitated 
by hydrochloric, acetic, or nitric acid ; when diluted with strong 
90 per cent, alcohol it gives an abundant precipitate ; and it is pre- 
cipitated by tannin, mercuric chloride, and platinic chloride. Pep- 
tone is not readily coagulated by heat, and it freely diffuses through 
membranes. It appears to be isomeric with albumen. Pro-peptone, 
para-peptone, or hemialbumose, is a mixture of substances interme- 
diate between albumen and peptone. It readily diffuses through 
membranes. Some vegetables, notably the leaves of the papaw tree, 
Carica papaya, appear to contain a principle, "papain,"' analogous 
in properties to pepsin. According to Wurtz, papain is an albu- 
menoid. 

Pepsiniim Saccharatum, U. S. P., is prepared by triturating 1 part 
of pepsin and 9 of sugar of milk. "Saccharated pepsin, when tested 
by the process given above, with the modification that 0.67 grm. of 
it is to be taken, should digest three hundred times its own weight 
of freshly coagulated and disintegrated egg albumen." — U. S. P. 

(For a resume of the modes of preparing pepsin see an article by 
Petit in the Pharmaceutical Journal for July 17, 1880.) 

Pancreatin. 

The pancreas (or " sweetbread ") secretes a colorless fluid which 
contains 1 J to 2 J per cent, of an albumenoid substance, or mixture 
of enzymes, which has the power of converting starch into sugar, 
and, especially, of emulsifying fat. It may be precipitated by sodium 
chloride from an acidulated infusion of the pancreas. Stutzer obtains 
a powerful extract by digesting the pancreas in lime-water and 



552 ORGANIC CHEMISTRY. 

glycerin with free exposure to air. It is soluble in cold water. An 
extremely small proportion emulsifies a large volume of fat. Pan- 
creatine is now official (Pancreatinum, U. S. P.) ; it is a yellowish 
to gray amorphous powder with a faint odor and taste, soluble in 
water, but not in alcohol. " If there be added to 100 cc. of tepid 
water contained in a flask 0.28 grm. of pancreatine and 1.5 grms. 
of sodium bicarbonate, and afterward 400 cc. of fresh cow's milk 
previously heated to 38° C. (100.4° F.), and if this mixture be main- 
tained at the same temperature for thirty minutes, the milk should 
be so completely peptonized that, if a small portion of it be trans- 
ferred to a test-tube and mixed with some nitric acid, no coagulation 
should occur. Peptonized milk, prepared in the manner just de- 
scribed, or even when the process is allowed to go on to the devel- 
opment of a very distinct bitter flavor, should not have an odor 
suggestive of rancidity." — U. S. P. The pancreatic juice would 
seem to contain four distinct ferments — namely, the emulsifying 
principle, the milk-curdling ferment, pancreatic diastase, and a pep- 
sin-like substance termed trypsin, which, unlike pepsin, attacks 
albumenoids in neutral or even slightly alkaline fluids. 

Bile. 

Bile (Fel Bovis, U. S. P.) is officially the gall or bile of the ox 
(Bos taurus, Linn.), which, evaporated to one-fourth of its bulk and 
freed from mucus by agitating with twice its bulk of rectified spirit 
(in which mucus is insoluble), filtering and evaporating, yields the 
official Purified Ox-bile (Fel Bovinum Purificatum, U. S. P.): the 
latter has the appearance of a yellowish-green soft resin, but is 
chiefly composed of two crystalline substances having the constitu- 
tion of a soap •, the one is termed sodium taurocholate (NaC 26 H 44 N0 7 S), 
the other is sodium glycocholate, or simply cholate (NaC 26 H 42 NQ 6 ). 
Both taurocholates and glycocholates are conjugated bodies, readily 
yielding, the former cholic or cholalic acid (HC 24 H 39 5 ) and taurine 
(C 2 H t N0 3 S), the latter cholalic acid and glycocine or glycocoll or 
amidacetic acid, CH 2 (NH 2 )COOH, a soluble crystalline body having 
interesting physiological relations, for it is obtainable from gelatin 
(hence the name glycocoll or sugar of gelatin, from ylvuvg, glucus, 
sweet, and Kolla, kolla, glue) and from hippuric acid. Choline 
(C 5 H 15 N0 2 ) is an alkaloid originally found in bile, hence its name 
(xo^, chole, bile), but it occurs in the brain, etc., in cod-liver oil, 
and in plants — ergot, Indian hemp, ipecacuanha, etc. ( Vide Index, 
"Choline.") 

Tests for Bile.— The presence of bile in a liquid, such as 
urine, may be detected by the following tests : The fluid is 
gradually mixed with half its bulk of strong sulphuric acid in 
a test-tube, rise of temperature being prevented by partial im- 
mersion of the tube in water. A small quantity of powdered 
white sugar is then introduced and well mixed with the acid 
liquid, and more sulphuric acid then poured in ; as the tem- 
perature rises a reddish or violet coloration is produced. The 



COLORING-MATTERS. 553 

cholalic acid liberated in the reaction furnishes the color. This 
is Pettenkofer's test. It is somewhat interfered with by albu- 
men and volatile oils. Quinlan tests for bile by placing a 
three-millimetre stratum of the suspected fluid before the slit 
of the spectroscope, and observing the absorption, which ex- 
tends, according to the amount present, from the violet of the 
spectrum to the Fraunhofer line d. 



QUESTIONS AND EXERCISES. 

In what form is albumen familiar ?— Name the chief tests for albumen. 
— Why is the administration of albumen useful in cases of poisoning? — 
Mention the points of difference between yolk and white of egg. — From 
what sources other than egg may albumen be obtained ? — In what re- 
spects does fibrin differ from albumen ? — Enumerate the chief constituents 
of blood. — How may fibrin be obtained from blood? — State the difference 
between casein, fibrin, and albumen. — What are the relations of cream, 
butter, curds and whey, and cheese to milk ? — Describe the microscopic 
appearances of blood and milk. — How much cream should be obtained 
from good milk? — What is the percentage of water in genuine milk ? — 
Name the sources of vegetable albumen and vegetable casein. — Give the 
percentage of nitrogen in albumenoid substances. — Describe the chemical 
nature of musk. — In what lie the peculiarities of gelatigenous substances ? 
— To what extent do isinglass, glue, and size differ? — Whence is pepsin 
obtained, and how prepared ? — Give the proximate constituents of bile. — 
What are the tests for bile? 



COLORING-MATTERS. 

The animal, vegetable, and mineral kingdoms abound in sub- 
stances or pigments which powerfully decompose light, absorbing 
certain of its constituent colors and reflecting the others. Thus, 
for example, most leaves contain a body termed chlorophyll, which 
has the property of absorbing red light and reflecting green ; these 
reflected rays, entering the eye of an observer and striking on the 
retina (the expanded extremity of the optic nerve), always communi- 
cate the same impression to the brain ; in popular language the leaf 
is said to be green. Art has richly supplemented the number of 
such natural coloring-matters. 

Yellow. — 1. Chrome yellow occurs in more than a dozen shades. 
(See Lead Chromate.) 2. Fustic or yellow wood is the wood of the 
Rhus cotinus. 3. Gamboge. (See Gamboge.) 4. Ochre is met with 
of many tints, under the names of yellow ochre, gold yellow, gold 
earth or ochre, yellow sienna, Chinese yellow. It is chiefly a mixture 
of iron oxyhydrates with alumina and lime. It has been used from 
the earliest times. 5. Orpiment is an arsenum sulphide (As 2 S 3 ). 6. 
Persian berries, or Avignon grains, contain a yellow principle 
termed rhamnin and other crystalline bodies ; they are the product 
of two or three species of Rhamnus. 7. Purree, or Indian yellow, 
is said by Stenhouse to owe its color to magnesium purrate or euxan- 



554 



ORGANIC CHEMISTRY. 



thate (MgC 42 H 34 22 ). 8. Quercitron is the bark of Quercus tinc- 
torial it contains the yellow glucoside quercitrin (C 36 H 38 O 20 ), 9. 
Rhubarb. (See Chrysophanic Acid, p. 338.) 10. Saffron {Crocus, B. P.), 
the dried stigma and part of the style of Crocus sativus, yields 
saffranin or polychroite, an orange-red glucoside, which, by the action 
of dilute acids and by other means, breaks up as shown in the fol- 
lowing equation, yielding red crocin (Weiss) : 



C^all 60^18 



+ H 2 

Polychroite. Water. 



!(C 16 H 18 6 ) 4- C 10 H 14 O + 

Crocin. Vol. oil of saffron. 



Sugar. 



Kayser, however, gives the formula of pure crocin as C 44 H 70 O 28 , and 
states that by absorption of water, 7H 2 0, it yields pure crocetin, 
C 34 H 46 9 , and sugar, 9C 6 H 12 6 . Any admixture of calcium carbonate, 
barium or calcium sulphates, or similar powder with saffron is 
readily detected on placing a little in a glass of warm water and 
stirring, when insoluble powder is deposited. " Ignited with free 
access of air, it should yield not more than 6 per cent, of ash " (B. P.). 
11. Turmeric, the rhizome of Curcuma longa, owes its yellow color 
to curcumin, a resin, the formula of which is said by Daube to be 
C 10 H 10 O 3 , and by Ivranof, C 16 H 16 4 . Jackson and Menke state that 
curcumin is an acid, and that its formula is H 2 C 14 H 12 4 . Apparently 
two yellow pigments are present. The coloring-matters of turmeric 
are readily dissolved by chloroform — not so those of saffron, mustard, 
or the best East-Indian rhubarb, on which fact methods of detecting 
turmeric in those substances have been founded (Howie, Pharma- 
ceutical Journal, November 1, 1873). 12. Weld (Reseda luteola) 
contains a durable yellow matter termed luteolin (C 20 H 14 O 3 ). 13. 
Picric or carbazotic acid (p. 454) is a very powerful yellow dye. 
14. Dried and powdered carrots yield to carbon disulphide a yellow 
coloring-matter, " carrotin," which is obtained on evaporating the 
solvent. It is said to be used in coloring butter. 

Red. — 1. Alkanet, the root of Alkanna tinctoria, Tausch, Anchusa 
tinctoria, Desf., yields anchusin (C 35 H 40 O 8 ), a resinoid matter soluble 
in oils and fat. 2. Annatto, Arnatto, or Arnotto, a paste prepared 
by evaporating a strained aqueous extract of the seeds of Bixa 
Orellana, contains bixin (C 28 H 34 5 ), an orange-red, and orellin, a 
yellow principle. 3. Brazil-ioood {Ccesalpinia Brasiliensis) fur- 
nishes brezilin, C 16 H 14 5 , the basis of several lakes ; sapan-wood and 
cam-wood probably contain the same substance. 4. Cinnabar. 
Chinese red, vermilion, or Paris red, is mercuric sulphide. It is a 
very ancient red pigment. 5. Chrome-red, is lead oxychromate. 
6. Cochineal (p. 337). 7. Madder, the root of Rubia tinctoria 
powdered and treated with sulphuric acid and acidulated water to 
effect the removal of earthy and other inert matters, furnishes a 
residual powder termed garancin. Garancin yields to pure water 
alizarin, C ]4 H 10 O 4 ,3H 2 O, the red, neutral, crystallizable coloring- 
matter of madder. Alizarin does not exist ready formed in the 
plant, but is derived by fermentation from a glucoside termed rubi- 
anic acid. Alizarin is now largely produced artificially from anthra- 
cene, one of the solid constituents of coal-tar (see p. 434). 8. Mul- 
berry juice {Mori Succus, B. P.) contains a violet-red coloring-matter 



COLORING-MATTERS. 555 

which has not been chemically examined. 9. Red lead (p. 212). 
This and the following ochre are very ancient red coloring-matters. 
10. Red ferric oxide, of shades varying from light to brown-red, is 
found native. The common names of it are Armenian bole, Berlin 
red, colcothar, English red, red ochre, burnt ochre, red earth, terra 
di Sienna, mineral purple, stone-red, and Indian red. 11, Redsand- 
ers-wood or red sandal-wood or bar-wood (Pterocarpi lignum, B. P:), 
the billets and chips of Pterocarpus santalinus, owes its color to 
santalin (C 4 H 12 4 ), a crystalline resinoid matter. Crystalline ptero- 
carpin, C 10 H 8 O 3 , and homopterocarpin, C 12 H 12 3 , are also present 
(Cazeneuve). 12. Red-poppy petals (Rhceados petala, B. P.), from the 
Papaver Rhosas, contain a red coloring principle which has not yet 
been isolated in a state of purity. The author has sought for mor- 
phine in large quantities of the petals, but could not find a trace of 
that alkaloid. 13. Red-rose petals (Rosw Gallicce Petala, B. P.) and 
those of the cabbage rose (Rosas Centifolice Petala, B. P.) also yield 
a red substance which has not been analyzed. 14. Safflower, dyer's 
saffron, or bastard saffron, the florets of Carthamus tinctorius, con- 
tains an unimportant yellow dye and 5 per cent, of carthamin 
(C u H 16 7 ), an uncrystallizable red dye, the pigment of the old pink 
saucers. Carthamin seems to possess acid characters, and (like 
silicic acid and other substances) to be soluble in water for a certain 
time after liberation from its alkaline solution ; for fabrics are dyed 
with safflower by immersion in a bath made of an infusion in dilute 
alkali neutralized by citric acid immediately before use, the carthamin 
probably penetrating the cells and vessels of the fibres in a soluble 
form, there becoming insoluble and imprisoned, and thus giving 
permanent color to the wool, silk, or other material. Mixed with 
French chalk, carthamin is used as a cosmetic under the name of 
vegetable rouge — carmine being animal rouge, and red oxide of iron 
the mineral rouge. 15. Lac-dye is a cheap form of cochineal, and is 
also yielded by the species of Coccus whose resinous excretion con- 
stitutes lac (stick-lac, seed-lac, or shell-lac, according to its condition 
as gathered off the twigs on which it is deposited, or as roughly 
separated from impurities in seed-like powder or lumps, or as melted 
and squeezed through bags into shell-like pieces). 16. Logwood 
(Hosmatoxylon, U. S. P.) contains a yellow substance, hematoxylin 
(C 16 H u 6 ,H 2 or 3H 2 0), to which any medicinal usefulness of the 
wood is perhaps due, and which, under the influence of air and 
alkali or ferments, assumes a very intense red color — hozmatein. 
Under the influence of ammonia and air also hematoxylin yields 
greenish-violet, iridescent scales of this hoematein (C 16 H 12 3 3H 2 0). 
17. Red enamel colors, for glass-staining and ceramic operations, are 
produced either by cuprous silicate or purple of Cassius (p. 247). 

Blue. — 1. Cobalt oxide precipitated in combination or admixture 
with alumina or calcium phosphate forms Thenard's blue, cobalt- 
blue, Hoffners blue, and cobaltic ultramarine. 2. Smalt, Saxony 
blue or king's blue, is rough cobalt glass in fine powder (p. 235). 3. 
Copper-blue, mountain-blue, and English or Hambrd 1 blue are chiefly 
copper oxycarbonates. 4. Indigo, C 16 H 10 N 2 O 2 , sommaruga (p. 291). 
5. Litmus, lichen-blue, turnsole, orchil or archil, and cudbear ar* 



556 ORGANIC CHEMISTRY. 

products of the action of air and alkalies on certain colorless prin- 
ciples, as orcin (C 6 H 3 (OH) 2 CH 3 ), derived from different species of 
lichen — Roccella, Variolaria, and Lecanora. 6. Prussian blue 
(p. 341) and TurnbulVs blue (p. 342) are met with under the names of 
Erlangen, Louisa, Saxon, Paris, or Berlin blue. 7. Ultramarine, a 
very old blue pigment, formerly obtained from the rare mineral lapis 
lazuli, is now cheaply made on a large scale by roasting a mixture of 
fine white clay, sodium carbonate, sulphur, and charcoal or rosin. 
Its constitution is not well made out. Acids decompose it, sulphur- 
etted hydrogen escaping. 

Purple. — See Murexid, p. 362. 

Green. — 1. Cupro-arsenical green pigments (p. 178). Most of 
the ancient greens contain copper carbonate. The old emerald green 
is a hydrous chromium oxide, but copper aceto-arsenite is now sold 
under this name. 2. Chlorophyll, leaf-green, or chromule. A method 
of extracting chlorophyll is given under "Extracts" (vide Index). 
It is resinoid, soluble in alcohol and ether, insoluble in water, and, 
according to Fremy and to Schunck, consists of a blue substance, 
phyllocyanin (C 34 H 68 N 4 17 ?), and a yellow, phylloxanthin : the yel- 
low tints in fading autumnal leaves, he says, are due to the latter 
principle, the former being the first to fade. Chlorophyll would 
probably well repay extended investigation, as it has never been 
obtained pure. 3. Sap-green, buckthorn-, vegetable-, or bladder-green, 
known also as Chinese green or lokas, is obtained by evaporating to 
dryness a mixture of lime and the juice [Rhamni Succus, B. P., 1867) 
of the berries of buckthorn (Rhamnus catharticus). It is soluble in 
water, slightly in alcohol, and insoluble in ether and oils. 4. Green 
ultramarine is made by a process similar to that for blue ultra- 
marine. 5. Mixtures of blue and yellow pigments and dyes are 
common sources of green colors. 6. Glass and earthware are colored 
green by chromium oxide and black copper oxide. 

Brown. — 1. Umber, sienna, or chestnut brown is found native. By 
heat it is darkened in tint, and is then known as burnt umber. It 
is a mixture of iron oxide, silica, and alumina. 2. Sepia is a dried 
fluid from the ink-bag of cuttle-fishes (Sepiadai) ; by its ejection into 
adjacent water the animal is said to obtain opportunity of escape 
from enemies. 3. Catechu (p. 359) furnishes a brown coloring- 
matter. 

Black. — 1. Black-lead (p. 30), bone-black (p. 112), or ivory-black 
and lamp-black, the latter a deposited soot from the incomplete 
combustion of resin and tar, are varieties of carbon. 2. Burnt sugar 
or caramel (p. 471). 3. Indian ink is usually a dried mixture of 
fine lampblack and size or thin glue. 4. Black ink is essentially 
tannates and iron gallates suspended in water containing a little 
gum in solution. 5. Printer's ink is well-boiled linseed or other oil 
mixed with good lampblack, vermilion, or other pigment. 6. Black 
dyes are of the same nature as ink. 7. The old u pigmentum nigrum " 
of black feathers, such as those of the common rook, of dark hair, 
and probably also of the skin of the negro, is, doubtless, the black 
substance which remains undissolved when black feathers are 



GENERAL QUALITATIVE ANALYSIS. 557 

digested for some time in dilute sulphuric acid. It is said to have 
the formula C 18 H 16 N 2 8 (Hodgkinson and Sorby). 

White Pigments.— 1. Chalk ov whiting (p. 111). 2. French chalk, 
steatite, or soapstone, is largely magnesium silicate. 3.. Heavy white 
(p. 103). 4. Pearl-white (p. 252). 5. Plaster of Paris (p. 106). 
6. Starch (p. 472). 7. White lead or Cremnitz white (p. 210). 
8. Zinc white or Chinese white (p. 134). 9. " Constant" white is 
barium tungstate. 10. Flake white is basic bismuth nitrate. 
11. Tin and zinc oxides and calcium phosphate are employed for 
giving a white opacity to glass. 

Aniline Colors. — Coal-tar Colors. — Within the last ten years 
nearly every shade of color seen in the animal and vegetable king- 
doms has been successfully imitated by certain dyes and pigments 
primarily derived from a mineral, coal. Coal distilled for gas 
furnishes tar or gas-tar. Coal-tar contains some aniline ; but especially 
it contains a liquid convertible into aniline — namely, benzene (C 6 H 6 ), 
first discovered by Faraday in compressed oil-gas. From aniline, by 
oxidation, Runge obtained the violet-color reaction, the body pro- 
ducing which Perkin afterward studied and isolated, and manu- 
factured under the name of mauve. Aniline-red {fuchsine, magenta, 
or roseaniline), aniline-yellow, aniline-green, aniline-blue, and, in 
short, aniline dyes, lakes, and pigments of every hue of the rain- 
bow, are now common articles of trade. Their application has 
revolutionized the arts of the dyer and color-printer. Some of the 
coal-tar colors are not " aniline " colors, being derived from naph- 
thalene, phthalic acid, phenol, etc. 



QUESTIONS AND EXEECISES. 

Explain the production of color by the various natural and artificial 
pigments. — Mention the chief yellow coloring-matters, and describe 
their chemical nature. — What isannatto? Name the colorific constitu- 
ent of madder. Can it be made artificially ? — State the source of litmus. 
— Distinguish between prussian blue and Turnbull's blue, and state 
how they are manufactured. — How is blue ultramarine obtained? How 
is it affected by acids? — Describe the chemical nature of the coloring 
principles of leaves. — By what agents is glass colored green ? — Whence 
is sepia obtained ? — Describe the chemistry of black ink. — Write a few 
sentences on aniline colors. 



QUALITATIVE ANALYSIS OF SUBSTANCES 
HAVING UNKNOWN PROPERTIES. 

Substances are presented to the analyst in one of the three forms 
in which all matter exists — namely, solid, liquid, or gaseous — and 
they may contain animal or vegetable as well as mineral matter. 

The method of analysis in the case of solid mineral bodies has been 
described on pp. 370 to 378. 

Solid animal or vegetable substances (or mixtures of these with 
mineral bodies) may be indefinite and beyond the grasp of chem- 



558 GENERAL QUALITATIVE ANALYSIS. 

istry, or definite and quite within the range of proximate qualita- 
tive organic analysis. The presence of such substances is indicated 
in the preliminary examination of a solid (pp. 371 to 374) by char- 
ring and other characters. If no charring occurs and no volatile 
liquid is expelled by heat, the absence of such matter is indicated. 
But if organic matter is present, an endeavor is made to ascertain 
its precise character. The analyst's knowledge of the history of 
the substance or the circumstances under which it comes into his 
hands will probably afford a clue to its nature, and enable him to 
search directly for its proximate constituents. If no such informa- 
tion is at hand, the action of solvents may be employed, as likely 
to afford indication of the general, if not of the precise, nature of 
the substance. Water, alcohol, ether, chloroform, carbon bisulphide, 
each hot and cold, may in turn be agitated with the substance, the 
mixture be filtered, a portion of the filtrate evaporated, at first 
partially, setting the product aside, and afterward to dryness, and 
any deposit or residue be examined with and without the aid of 
a microscope. Other portions of the filtrate may be treated with 
acids, alkalies, and solutions of such metallic salts as are com- 
monly used as group-tests for acidulous radicals (p. 369). The 
action of alkalies, as well as acids, weak and strong, hot and cold, 
may also be tried on the solid substance itself, and colors, odors, 
and, in short, any effect whatever, be duly noted. A portion of 
the substance should also be burnt in an open porcelain crucible 
until no carbon remains, and the ash, if any, be examined : its 
amount and nature may afford information leading to the identifica- 
tion of the substance. 

The foregoing experiments having been carefully performed and 
all results entered in the note-book, a little reflection will possibly 
lead to recognition, or may suggest further direct experiments or 
confirmatory tests, or will, at least, have pointed to the absence of 
90 or 95 per cent, of all possible substances, and thus have restricted 
the area of inquiry to narrow limits. The success attainable in 
qualitative proximate organic analysis by the medical or pharma- 
ceutical student will of course largely depend on the thoroughness 
with which the operator has prosecuted his study of practical chem- 
istry generally ; but it also will be considerably affected by the 
extent to which he has cultivated the art of observation, and the 
opportunities he has had of acquiring a knowledge of the appear- 
ance, uses, and common properties of definite chemical substances 
and of articles of food, drink, and medicine. The most successful 
of several good analysts will be the one who has most common 
sense and most experience. 

The pharmaceutical student, who has probably already had some 
years of experience in pharmacy, occupies an unusually favorable 
position for prosecuting the proximate analysis of organic and 
inorganic substances, or, at all events, of that large proportion of 
such bodies met with in the domain of hygiene and pharmacy. 
Many substances he will identify at sight or by aid of a lens, or 
after applying some simple physical or chemical test. Nor should 
he find much difficulty, after reaching the present point of practical 



GENERAL QUALITATIVE ANALYSIS. 559 

study, in deciding whether the solid substance under examination 
belongs to the _ class of organic acids, organic salts of metallic 
radicals, alkaloids, salts of alkaloids, amylaceous matter, gums, 
saccharine substances, glucosides, albumenoid matters, fats, soaps, 
resins, coloring-matters, etc. For instance, the pharmaceutical 
student will find less difficulty than the general student in success- 
fully analyzing a substance occurring in " scales," because he has 
experience of the appearances of compounds commonly produced 
in that form, and because, even if the appearance is new to him, 
he knows what kind of substances most readily lend themselves to 
production in that form. While the general student is testing 
generally and proceeding cautiously, or searching for general infor- 
mation in books of reference, the pharmaceutical or medical student 
has incinerated some of the material, noticed whether or not the 
ash is red (iron) and strongly alkaline (potassium), treated more of 
the material with an alkali (for ammonium), added excess of 
ammonia, and examined the precipitate (for cinchonine or quinine), 
or shaken up the alkaline liquid successively with ether and chloro- 
form, and tested the residue of these decanted and evaporated 
solvents (quinine, beberine, strychnine), and examined the aqueous 
solution of the material or one of the filtered alkaline liquids in 
the usual way for acidulous radicals (citric, tartaric, sulphuric, 
hypophosphorous). Or he has modified his methods to include 
search for some " scale preparation" which his special knowledge 
tells him has been newly introduced to, or is rare in, pharmacy. 

In the case of liquids the solvents as well as the dissolved mat- 
ters claim attention. A few drops are evaporated to dryness on 
platinum-foil to ascertain if solid matter of any kind is present ; 
the liquid is tested by red and blue litmus-paper to ascertain if free 
alkalies, free acids, or neither are present-, a few drops are heated 
in a test-tube and the odor of any vapor noticed, a piece of glass 
tubing bent to a right angle being, if necessary, adapted to the 
test-tube by a cork, and some of the distilled liquid collected and 
examined ; finally, the usual group-reagents for the several basylous 
and acidulous radicals are consecutively applied. 

Proceeding in this way, the student who has already had some 
experience in pharmacy will not be likely to overlook such solvents 
as water, acids, alkalies, alcohol, glycerin, ether, chloroform, ben- 
zene, fixed oils, and essential oils, or to miss the substances which 
these menstrua may hold in solution. He will probably also recog- 
nize such liquids as carbolic acid, formic acid, lactic acid, methylic 
alcohol, aldehyde, aniline, nitrobenzene. He must not, however, sup- 
pose that he will always be able to qualitatively analyze, say, a bottle 
of medicine, for the various infusions, decoctions, tinctures, wines, 
syrups, liniments, confections, extracts, pill-masses, and powders 
contain vegetable matters, most of which at present are quite beyond 
the reach of the analyst. Neither the highest skill in analysis nor 
the largest amount of experience concerning the odor, appearance, 
taste, and uses of drugs is sufficient for the detection of all these 
vegetable matters. Skill and experience combined, however, will 
do much ; and in most cases even so difficult a task as the one just 



560 GENERAL QUALITATIVE ANALYSIS. 

mentioned may be accomplished with reasonable success. Obvi- 
ously, qualitative analysis alone will not enable the operator to 
produce a mixture of substances similar to that analyzed ; to this 
end recourse must be had to quantitative analysis, a subject treated 
subsequently. 

Natural fluids, as "Milk" and "Urine" (vide Index), admit of 
special analytical treatment. 

Gas-analysis, or eudiometry (from evdia, eudia, calm air, and 
fiirpov, metron, a measure, in allusion to the eudiometer, an instru- 
ment used in measuring the proportion and, as the early chemists 
thought, the salubrity of the gases of the air), is a branch of exper- 
imental investigation, chiefly of a quantitative character, concern- 
ing which information must be sought in other treatises. The anal- 
ysis of atmospheric air from various localities, coal-gas, and gases 
obtained in chemical researches involves operations which are 
scarcely within the sphere of Chemistry applied to Medicine. Be- 
yond the recognition, therefore, of oxygen, hydrogen, nitrogen, chlo- 
rine, carbonic, sulphurous, nitrous, and hydrosulphuric acid gases, 
etc., the experimental considerations of the chemistry of gaseous bodies 
may be omitted. Their study, however, should not be neglected, as 
existing conceptions of the constitution of chemical substances are 
largely dependent on the observed relations of the volumes of 
gaseous compounds to their elements. (See previous paragraphs, 
pp. 19-30, 42-46, 52-56, and 130.) A useful work on the latter 
part of the subject is a small book by Hofmann, " Introduction to 
Modern Chemistry." 

Spectrum Analysis. — It may be well to state here that the prelim- 
inary and final examinations of minute quantities of solid matter 
may, in certain cases, profitably include their exposure to a temper- 
ature at which they emit light, the flame being physically analyzed 
by a spectroscope. A spectroscope consists essentially of a prism 
to decompose a ray of light into its constituent colors, with tubes 
and lenses to collect and transmit the ray or rays to the eye of an 
observer. The material to be examined is placed on the end of a 
platinum wire, which is then brought within the edge of a spirit- 
lamp or other smokeless flame ; volatilization, attended usually in 
the case of a compound by decomposition, at once occurs, and the 
whole flame is tinged with a characteristic hue. A flat ribbon of 
rays is next cut off by bringing near to the flame a brass tube, the 
cap of which is pierced by a narrow slit. At the other end of the 
tube, at focal distance for parallel rays, is a lens through which the 
ribbon of light passes to a pi-ism ; the prism decomposes the ribbon, 
spreading out its constituent colors like a partially opened fan, and 
the colored beam or spectrum thus produced is them examined by 
help of a telescope attached by a movable joint to a stand which 
carries the prism and the object-tube. It is this combination of 
tubes, lenses, and prism or prisms which constitutes the spectro- 
scope. Sodium compounds under the circumstances give yellow 
light only, indicated by a double band of light in a position corre- 
sponding to a portion of the yellow part of an ordinary solar spec- 
trum. The potassium spectrum is mainly composed of a red and 



CHEMICAL TOXICOLOGY. 561 

violet band ; lithium, a crimson and, at very high temperatures, 
a blue band. Most of the other elements give equally characteristic 
spectra. 

By passing white light through a colored substance an " absorp- 
tion spectrum " will be produced which is often characteristic, as in 
the case of blood or chlorophyll, while by aid of a combined micro- 
scope and spectroscope (microspectroscope) drops of colored fluids 
can be analyzed. 



CHEMICAL TOXICOLOGY. 

In cases of criminal and accidental poisoning the substances 
presented to the chemical analyst for examination are usually articles 
of food, medicines, or vomited matters, or the liver, kidneys, intes- 
tines, stomach, and contents, removed in course of post-mortem ex- 
amination. In these cases some special operations are necessary 
before the poison can be isolated in a state of sufficient purity for the 
application of the usual tests ; for in most instances the large quan- 
tity of animal and vegetable — or, in one word, organic — matter 
present prevents or masks the characteristic reactions on which the 
tests are founded. These operations will now be described ; * they 
form the chemical part of the subject of Toxicology {to^lkov, toxicon, 
poison, and Idyoc, logos, discourse). 

Substances occurring apparently as definite salts or unmixed with 
organic matter need no special treatment. They are analyzed by 
the ordinary methods already given, attention being restricted to 
poisonous compounds. 

EXAMINATION OF AN ORGANIC MIXTURE SUSPECTED TO CON- 
TAIN MERCURY, ARSENUM, ANTIMONY, LEAD, COPPER, 
CHROMIUM, OR ZINC ; SULPHURIC, NITRIC, HYDROCHLORIC, 
OXALIC, OR HYDROCYANIC ACIDS; CAUSTIC ALKALIES; 
PHOSPHORUS ; STRYCHNINE, MORPHINE, OR OTHER POI- 
SONOUS ALKALOIDS. 



Preliminary Examination. 

Odor, Appearance, Taste. — Smell the mixture, with the view 
of ascertaining the presence or absence of any notable quantity 
of free hydrocyanic acid. Look carefully for any small solid 
particles, such as arsenic, corrosive sublimate, or verdigris, and 
for any appearance which may be regarded as abnormal, any 
character unusual to the coffee, tea, beer, medicine, vomit, coats 

* Materials for these experiments are readily obtained for educational 
purposes by dissolving the poison in infusions of tea or coffee, in porter, 
or in water to which some mucilage of starch or linseed meal, pieces of 
bread, potato, and fat have been added. 



562 CHEMICAL TOXICOLOGY. 

of stomach, kidney, liver, or other organ, tissue, or solid mat- 
ter under examination. 

Poisonous Quantity of Acid. — Add to a small portion some 
solution of sodium carbonate, with the view of ascertaining 
by strong effervescence the presence of any large, poisonous 
quantity of sulphuric, nitric, or hydrochloric acid (p. 564). 

Poisonous Quantity of Alkali. — If so excessively alkaline as 
to require the addition of a very large quantity of acid before 
neutralization is effected, a noxious quantity of a corrosive or 
caustic alkali is present. Whether soda or potash, etc. is ascer- 
tained by the usual tests. 

Special Instructions may induce the operator to suspect the 
presence of one particular poison. Direct examination for the 
latter may then be made, either at once if the substance has 
an aqueous character, or when nitration or treatment with warm 
hydrochloric or acetic acid has afforded a more or less colorless 
liquid. 

Fluids. — A vomit or the contents of a stomach, if set aside 
in a long narrow vessel (test-glass or ale-glass)), or, better, ex- 
posed on a filter during a night, will often yield a more or less 
limpid portion at the bottom or top of the solid matter. This 
fluid (separated by a pipette or otherwise) will sometimes 
respond to tests without further preparation, and always 
requires less preparatory treatment than a semi-solid mixture. 
If none passes through a filter, a portion often collects in the 
upper part. 

General Procedure. — If the preliminary examination does not 
indicate the method to be pursued, proceed as follows, treating 
a portion (not more than one-fourth) of the mixture for the 
poisonous metals, another for the acids, and a third for alka- 
loids, reserving the remainder for any special experiments which 
may suggest themselves : 

Examination for Mercury, Arsenum, Antimony, Lead, Copper, 
Chromium, Zinc. 

If a liquid, acidulate with hydrochloric acid and boil for a 
short time. If solid or semi-solid, cut up the matter into small 
pieces, add enough water to form a fluid mixture, stir in 10 or 
20 per cent, of ordinary liquid hydrochloric acid, and boil until, 
from partial aggregation and solution of the solid matter, 
filtration can easily be effected. 

Heat a portion of the clear liquid with a thin piece of bright 
pure copper or copper gauze, about an inch long and a quarter 
of an inch broad, for about ten or twenty minutes ; metallic 



MERCURY, ARSENUM, ANTIMONY. 563 

mercury, arsenum, or antimony will be deposited on the copper, 
darkening it considerably in color. Pour off the liquid from 
the copper, carefully rinse the latter with a little co]d water, 
dry the piece of metal by holding it over or near a flame (using 
fingers, not tongs, or it may become sufficiently hot for a loss 
of mercury or arsenum to occur by volatilization), introduce it 
into a narrow test-tube or piece of glass tubing closed at one end, 
and heat the bottom of the tube in a flame, holding it horizon- 
tally, that the upper part of the tube may be kept cool, and 
partially closing the mouth with the finger to prevent escape 
of vapor. Under these circumstances any mercury will volat- 
ilize from the copper and condense on the cool part of the tube 
in a ring or patch of white sublimate, readily aggregating into 
visible globules on being pressed by the side of a thin glass 
rod inserted into the tube ; arsenum will volatilize from the 
copper, and, absorbing oxygen from the air in the tube, con- 
dense on the cool part of the glass in a ring or patch of white 
sublimate of arsenic (gray or even darker if much arsenum as 
well as arsenic be present), not running into globules when 
rubbed, but occurring in small crystals, the characteristic octa- 
hedral form of which (vide p. 172) is readily seen by aid of a 
good hand-lens or the low power of a microscope ; antimony 
volatilizes from the copper if strongly heated, and, absorbing 
oxygen, immediately condenses as a slight white deposit close 
to the metal. 

Confirmatory Tests. — 1. Nothing short of the production of glob- 
ules should be accepted as evidence of the presence of mercury. It 
will usually have existed as corrosive sublimate. 2. To confirm 
indications of the presence of arsenum, a portion of the acid liquid 
may be subjected to the hydrogen tests (pp. 173, 175), or the tube 
containing the white crystalline arsenic may be broken, and the part 
on which the sublimate occurs boiled for some time in water, and 
the hydrosulphuric acid, silver ammonio-nitrate, and copper am- 
monio-sulphate tests (pp. .176, 177), applied to the aqueous solution. 
3. For antimony a portion of the acid liquid must always be intro- 
duced into the hydrogen-apparatus with the usual precautions. 
(Vide p. 185.) 4. Any sulphur present may darken the copper, and 
such stained copper may subsequently yield' a whiiish sublimate of 
sulphur on the sides of the subliming tube ; such appearances, 
therefore, are consistent with the entire absence of mercury, arsenum, 
and antimony. 

Note.— Before finally concluding that arsenum is absent from a 
fluid the latter should be warmed with a little sulphurous acid, and 
ordinary tests then again applied, for arsenic acid and other arsen- 
ates are not readily affected by the usual reagents for arsenum. 

For lead and copper pass hydrosulphuric acid through the 



564 CHEMICAL TOXICOLOGY. 

clear acidulated liquid for some time, warming the liquid if no 
precipitate is produced, or diluting and partially neutralizing 
the acid by ammonia if much acid has been added. Collect on 
a filter any black precipitate that may have formed ; wash, dis- 
solve in a few drops of aqua regia, dilute, and apply tests, such 
as ammonia for copper, sulphuric acid for lead, or any other of 
the ordinary reagents (pp. 193, 215). 

Copper may be often at once detected in a small quantity of acidu- 
lated liquid by immersing the point of a penknife or a piece of 
bright iron wire — a deposit of copper, in its characteristic color, 
quickly or slowly appearing, according to the amount present 
(p. 193). 

Chromium and Zinc. — To the acid liquid through which sul- 
phuretted hydrogen has been passed add excess of ammonia 
(or to the original acid fluid add excess of ammonia, 
and then ammonium sulphydrate) ; a precipitate falls which 
may contain alumina, phosphates, chromium, and zinc. (It is 
usually blackish, from the presence of ferrous sulphide.) Col- 
lect the precipitate on a filter, wash, dissolve in a little hydro- 
chloric acid, add a few drops of nitric acid, boil, pour in excess 
of ammonia, filter, and test the filtrate with ammonium sulphy- 
drate ; a white precipitate indicates zinc. A green precipitate 
would indicate chromium. Chromates also should be sought 
(p. 240). 

Examination for Mineral Acids, and Oxalic and Hydrocyanic 

Acids. 

To detect hydrochloric, nitric, or sulphuric acid in a liquid 
containing organic matter, dilute with water and apply to small 
portions the usual tests for each acid, disregarding indications 
of small quantities. ( Vide pp. 268, 289, 310.) 

Excessive sourness, copious evolution of carbonic acid gas on the 
addition of sodium carbonate, and abundant evidence of acid on 
applying the various tests to small portions of the fluid presented 
for analysis, collectively form sufficient evidence of the occurrence 
of a poisonous amount of either of the three common mineral acids. 
Small quantities of the hydrochloric, nitric, and sulphuric radicals, 
occurring as metallic salts or acids, are common normal constituents 
of food ; hence the direction to disregard insignificant indications. 
If the fluid under examination be a vomit or the contents of a 
stomach, and an antidote has been administered, free acid will not be 
found, but, instead, a large amount of the corresponding salt. 

For oxalic acid, filter or strain a portion of the liquid, if not 
already clear, and add solution of lead acetate so long as a 






HYDROCYANIC ACID. 565 

precipitate occurs ; collect the precipitate, which in any case is 
only partly lead oxalate, on a filter, wash, transfer it to a test- 
tube or test-glass, add a little water, and pass hydrosulphuric 
acid through the mixture for a short time ; the lead is thus 
converted into the insoluble form of sulphide, while any oxalic 
acid is set free in the solution. Filter, boil to get rid of hydro- 
sulphuric acid, and apply the usual tests for oxalic acid (see 
p. 316) to the clear filtrate. 

The contents of a stomach containing oxalic acid will often be of 
a dark-brown color with a tinge of green (altered blood and mucus), 
and the viscid mixture generally, though slowly, affords some clear, 
limpid, almost colorless liquid by filtration or on standing. 

For hydrocyanic acid the three chief tests may be applied 
at once to the liquid or semi-liquid organic mixture, whether 
it has an odor of hydrocyanic acid or not. First : Half fill a 
small porcelain crucible with the material, add 8 or 10 drops 
of strong sulphuric acid, stir gently with a glass rod, and invert 
over the mouth of the crucible a watch-glass moistened with 
a small drop of solution of silver nitrate ; a white film on the 
silver solution is probably silver cyanide, formed by the action 
of the gaseous hydrocyanic acid on the silver nitrate. Second : 
Prepare a small quantity of the organic mixture as before, 
slightly moistening the centre of the watch-glass with solution 
of potash ; here, again, the heat generated by the action of the 
strong acid is sufficient to volatilize some of the hydrocyanic 
acid, which, reacting on the potash, forms potassium cyanide. 
On removing the watch-glass and stirring into it successively 
solution of a ferrous salt, a ferric salt, and hydrochloric acid, 
flocks of prussian blue are produced if hydrocyanic acid is 
present. Third : Proceed as before, moistening the watch-glass 
with ammonium sulphydrate ; after exposure to the hydrocy- 
anic acid gas for five or ten minutes add a drop of solution of 
ammonia, evaporate to dryness at a low temperature, and add 
a drop of hydrochloric acid and of solution of ferric chloride ; 
a blood-red color, due to ferric sulphocyanate, is produced if 
cyanogen is present. 

If the above reactions are not well marked, the organic mixture 
may be carefully and slowly distilled in a small retort, the neck of 
which passes into a bottle and dips beneath the surface of a little 
water at the bottom of the bottle ; the reagents may then be applied 
to separate portions of the distillate. 

The examination of organic mixtures for hydrocyanic acid must 
be made without delay, as the poison soon begins to decompose, and 
in a day or two is usually destroyed. 
25 



566 CHEMICAL TOXICOLOGY. 

Examination for Phosphorus. 

A paste containing phosphorus is commonly employed for 
destroying vermin. In cases of poisoning the phosphorus is 
generally in sufficient quantity to be recognized by its charac- 
teristic unpleasant smell. A stomach in which it occurs not 
infrequently exhibits slight luminosity if opened in a dark 
room. When the phosphorus is too small in quantity or too 
much diffused to afford this appearance, a portion of the mate- 
rial is placed in a flask, water acidulated by sulphuric acid 
added, a long wide glass tube fitted to the neck of the flask by 
a cork, and the mixture gently boiled. If phosphorus is pres- 
ent (even 1 part in 2,000,000, according to De Vrij), the top 
of the column of steam as it condenses in the tube will appear 
distinctly phosphorescent when viewed in a dark room. From 
its liability to oxidation phosphorus cannot be detected after 
much exposure of an organic mixture to air. 

Examination for Strychnine and Morphine. 

Strychnine. — If solid or semi-solid, digest the matter with 
water and about 10 per cent, of hydrochloric acid till fluid, 
filter, evaporate to dryness over a water-bath. If the organic 
mixture is already liquid, it is simply acidulated with hydro- 
chloric acid and evaporated to dryness. The acid residue is 
next treated with spirit of wine as long as anything is dis- 
solved, the filtered tincture evaporated to dryness over the water- 
bath, and the residue digested in water and filtered. This 
slightly acid aqueous solution must now be rendered alkaline 
by ammonia, and well shaken in a closed bottle or long tube 
with about half an ounce of chloroform, and set by till the 
chloroform has subsided. The chloroform (which contains the 
strychnine) is then removed by a pipette, the presence of any 
aqueous liquid being carefully avoided, and evaporated to dry- 
ness in a small basin over a water-bath, the residue moistened 
with concentrated sulphuric acid, and the basin kept over the 
water-bath for several hours. (It is highly important that the 
sulphuric acid used in this operation should be free from 
nitrous compounds. Test the acid, therefore, by adding pow- 
dered ferrous sulphate, which becomes pink if nitrous bodies 
are present. If these are found, the acid should be purified 
by strongly heating with ammonium sulphate, 70 or 80 grains 
to a pint.) The charred material is exhausted with water, 
filtered, excess of ammonia added, the filtrate shaken with 
about a quarter of an ounce of chloroform, the mixture set 
aside for the chloroform to separate, and the chloroform again 



MORPHINE AND MECONIC ACID. 567 

removed. If on evaporating a small portion of this chloro- 
form solution to dryness, adding a drop of sulphuric acid to 
the residue, and warming, any darkening of color or charring 
takes place, the strychnine is not sufficiently pure for chemical 
detection ; in that case the rest of the chloroform must be 
removed by evaporation, and the residue redigested in warm 
sulphuric acid for two or three hours. Dilution, neutralization 
of acid by ammonia, and agitation with chloroform are again 
practised, and the residue of a small portion of the chloroform 
solution once more tested with sulphuric acid. If charring still 
occurs, the treatment must be repeated a third time. Finally, 
a part of the chloroform solution is taken up by a pipette, and 
drop after drop evaporated on one spot of a porcelain crucible- 
lid until a fairly distinct dry residue is obtained. A drop of 
sulphuric acid is placed on the spot, another drop placed near, 
a minute fragment of red potassium chromate placed in the 
second drop, and, when the acid has become tinged with the 
chromate, one drop drawn across the other; the characteristic 
evanescent purple color is then seen if strychnine is present. 
Other tests (vide p. 528) may be applied to similar spots. 

This is Girdwood and Rogers's method for the detection of 
strychnine when mixed with organic matter. It is tedious, but 
trustworthy, and, though apparently complicated, very simple in 
principle, thus : Strychnine is soluble in acidulated water or alcohol 
or in chloroform, readily removed from an alkaline liquid by agita- 
tion with chloroform, and not charred or otherwise attacked when 
heated to 212° F. with sulphuric acid ; much of the organic matter 
of the food is insoluble in water ; of that soluble in water, much is 
insoluble in alcohol ; and of that soluble in both menstrua, all is 
charred and destroyed by warm sulphuric acid in a shorter or longer 
time. (See also Stas's general process, p. 568.) 

Morphine, and the Meconic Acid with which it is Associated in 
Opium. — To the liquid or the semi-fluid mixture, warmed for 
some time with a small quantity of acetic acid, filtered, and 
concentrated if necessary, add solution of lead acetate until no 
further precipitate is produced. Filter and examine the pre- 
cipitate for meconic acid, reserving the filtrate for the detection 
of morphine. 

The Precipitate. — Wash the precipitate (lead meconate, etc.) 
with water, place it in a test-tube or test-glass with a small 
quantity of water, pass hydrosulphuric acid gas through the 
mixture for a short time, filter, slightly warm in a small basin, 
well stirring to promote removal of excess of the gas, and add 
a drop of neutral solution of ferric chloride ; a red color, due 
to the formation of ferric meconate, is produced if meconic 
acid is present. This color is not destroyed on boiling the 



568 CHEMICAL TOXICOLOGY. 

liquid after the addition of one drop of diluted hydrochloric 
acid, as is the case with ferric acetate, nor is it bleached by 
solution of corrosive sublimate, thus distinguishing it from fer- 
ric sulphocyanate. It is discharged by hydrochloric acid. 

The Filtrate. — The solution from which meconic acid has 
been removed by lead acetate is evaporated to a small bulk 
over a water-bath, excess of potassium carbonate added, and 
evaporation continued to dryness. The residue is then treated 
with alcohol, which dissolves the morphine. The alcoholic 
solution, evaporated similarly, may leave the morphine suf- 
ficiently pure for the application of the usual tests (vide p. 518) 
to small portions of the residue. If no reaction is obtained, 
add a drop of sulphuric acid and a little water to the residue, 
and shake with ether, in which the salt of morphine is insol- 
uble. The treatment with ether may be repeated until nothing 
more is removed, the acid aqueous liquid saturated with potas- 
sium carbonate, the mixture evaporated to dryness, the residue 
digested in alcohol, filtered, and portions of the alcoholic liquid 
evaporated to obtain spots of morphine for the application of 
the ordinary tests. 

If much organic matter is believed to remain in the filtrate 
after the lead-acetate treatment, or if a considerable excess of 
lead acetate has been employed, the filtered liquid should be 
subjected to a current of sulphuretted hydrogen until no more 
lead sulphide is precipitated, the mixture filtered, and the 
filtrate, with the washings from the lead sulphide, evaporated 
to a small bulk, excess of potassium carbonate added, the whole 
well mixed and agitated with twice or thrice its bulk of a mix- 
ture of ether and acetic ether (ether alone might not dissolve 
the morphine). On standing, the ethereal liquid rises to the 
surface : it is carefully removed, evaporated to dryness, and 
the residue tested or further purified in the manner described 
in the preceding paragraph. 

The examination for morphine must be conducted with great 
care, and with as large a quantity of materialas can be spared ; for 
its isolation from other organic matter is an operation of difficulty, 
especially when only a minute proportion of alkaloid is present. 
Fortunately, the detection of meconic acid does not include similar 
difficulties, and, as its reactions are quite characteristic, its presence 
is held to be strong evidence of the existence of opium in an organic 
mixture. 

Examination for Other Poisonous Alkaloids. 

Stasis Process. — Minutely subdivide any solid matter ; to this 
and the liquid portion of the vomit, etc. add about twice their 






POISONOUS ALKALOIDS. 569 

weight of the strongest spirit of wine containing sufficient tar- 
taric acid to fairly acidify the mixture. Digest the whole in 
a flask at a temperature of 150° or 160° F. ; set aside to cool ; 
filter. The solution, which will contain the whole of the alka- 
loid, should then be evaporated nearly to dryness in vacuo, or 
at all events at a temperature not exceeding 100° F., lest vol- 
atile alkaloids should be dissipated. The residue is next ex- 
hausted with cold anhydrous alcohol, filtered, and the filtrate 
evaporated to dryness with the precautions already stated. 
The extract is dissolved in a very small quantity of water, 
treated with excess of powdered sodium or potassium bicar- 
bonate, and well shaken with five or six times its volume of 
pure ether (with perhaps a little acetic ether). This ethereal 
liquid contains the alkaloid. Small portions should be evap- 
orated in watch-glasses and tasted, or tested physically and 
chemically, according as the knowledge of collateral circum- 
stances by the operator or his experience or such reactions as 
are recorded on pp. 530, 543 may suggest. 

If a volatile alkaloid (conine, nicotine, lobeline, sparteine) is 
indicated, the ethereal solution, which may contain animal mat- 
ter, is removed, agitated with aqueous solution of potash, de- 
canted, and shaken with pure diluted sulphuric acid. On 
standing, the aqueous portion, containing the alkaloid as acid 
sulphate, subsides ; the upper ethereal portion, containing the 
animal matter, is rejected ; the acid aqueous liquid is made 
alkaline with caustic potash or soda ; ether added, well shaken ; 
the ethereal liquid decanted, evaporated to dryness in vacuo or 
at a low temperature, and (to get rid of all traces of ammonia) 
again moistened with ether and dried. The residue is now 
tested for the suspected alkaloid by taste, smell, and the ap- 
plication of appropriate reagents (pp. 530-543). 

If a non-volatile alkaloid (aconitine, atropine, brucine, col- 
chicine, emetine, hyoscyamine, physostigmine, solanine, vera- 
trine, as well as morphine, codeine, and strychnine, etc.) is 
indicated, further purify by decanting the ethereal liquid from 
the lower aqueous solution of sodium bicarbonate, removing 
the ether by evaporation, digesting the residue in alcohol, filter- 
ing, evaporating the alcohol, treating the residue with diluted 
sulphuric acid, setting aside for a few hours, filtering, concen- 
trating, adding powdered potassium carbonate, and finally anhy- 
drous alcohol. The alcoholic liquid, on evaporation, yields the 
alkaloid in a fit condition for testing in the manner already 
stated. 

Sonnenschein s Process. — Digest with diluted hydrochloric 
acid, evaporate to the consistence of syrup, dilute, set aside for 



570 CHEMICAL TOXICOLOGY. 

some hours, filter. Add solution of phosphomolybdic acid so 
long as any precipitate falls or cloudiness occurs ; collect the 
precipitate on a small filter ; wash it with water containing 
phosphomolybdic and nitric acids, and, while still moist, place it 
in a flask. Decompose this compound of phosphomolybdic acid 
and alkaloid by adding caustic baryta until the stirred mixture 
is distinctly alkaline. Distil off volatile alkaloids, condensing 
and collecting by help of a long tube so bent that the apparatus 
shall act as a retort, the end of the tube being attached to a 
bulb or a series of bulbs containing diluted hydrochloric acid. 
The acid liquid evaporated gives a residue of hydrochlorates 
of alkaloids. The latter will afford characteristic reactions 
with the tests for the suspected alkaloid, and, on being moist- 
ened with baryta-water and warmed, will afford fumes of volatile 
alkaloids, the odor of which is usually characteristic. The resi- 
due in the flask will contain non-volatile alkaloids. It is treated 
with carbonic acid gas to neutralize and precipitate the excess 
of baryta as insoluble barium carbonate ; the mixture is evap- 
orated to dryness over a water-bath, and the residue digested 
in alcohol. The alcoholic solution evaporated generally yields 
the alkaloids in a fit state for testing. 

Reagents for Alkaloids. 

Phosphomolybdic acid forms with ammonia, in acid solutions, a 
remarkably insoluble compound, and it comports itself in a similar 
manner with those compounds which are analogous to ammonia — 
the nitrogenized organic bases — consequently forming an excellent 
reagent for their detection. It may be prepared in the following 
manner : Ammonium molybdate is precipitated by sodium phos- 
phate ; the yellow precipitate, having been washed, is diffused 
through water and heated with sufficient sodium carbonate to dis- 
solve it. The solution is then evaporated to dryness, and calcined 
to drive off the ammonia. In case any of the molybdic compound 
be reduced by this operation, the residue must be moistened with 
nitric acid and again calcined. The dry mass is then dissolved in 
cold water, the solution strongly acidulated with nitric acid, and 
water added until 10 parts of the solution contain 1 of the dry salt. 
The liquid, which is of a golden-yellow color, must be preserved 
from ammoniacal fumes. It precipitates all the alkaloids (with the 
exception of urea) when a mere trace only is present. The precipi- 
tates are yellow, generally flocculent, insoluble in water, alcohol, 
ether, and the diluted mineral acids, with the exception of phosphoric 
acid. Nitric, acetic, and oxalic acids, concentrated and boiling, dis- 
solve them. These compounds are decomposed by the alkalies, 
certain metallic oxides, and the alkaline salts, which separate the 
alkaloid. To give an idea of the sensitiveness of this reagent, it 
may be stated that 0.000071 gramme of strychnine gives an appre- 






POISONOUS ALKALOIDS. 571 

ciable precipitate with 1 cubic centimetre of the solution of phos- 
phomolybdic acid. 

Phospho-antimonic and phosphotungstic acids are also precipitants 
of alkaloids. Platinum, iridium, palladium, and gold chlorides are 
occasionally serviceable. Tannic and picric acids, too, may be used, 
and a solution of iodine and potassium iodide. 

Other special reagents for alkaloids are " Mayer's ; " " Nessler's " 
(see Index) ; the double potassium and cadmium iodide ; and a solu- 
tion of the double "iodide of bismuth and potassium." The latter 
is made (by Thresh) by adding together 1 ounce of Liquor Bismuthi, 
B. P., 90 grains of potassium iodide, and 90 grains of strong hydro- 
chloric acid. This orange-colored solution gives a red precipitate 
with dilute cold solutions containing alkaloids. 

Ptomaines (wTCj/ua, a corpse) have already been alluded to as in- 
cluding poisonous alkaloids producible from putrefying animal 
matters, even the human body itself, during the ordinary processes 
of decay. They are distinguished, according to Brouardel and 
Boutmy, by a drop or two of a solution of their sulphate convert- 
ing a drop of solution of potassium ferricyanide into ferrocyanide, 
the mixture then giving a dark-blue precipitate with a ferric salt. 
Some other substances also, as morphine, possess this converting 
power. 

Tyrotoxicon. — This ptomaine (p. 513) may be isolated and tested 
as follows : Prepare an aqueous extract of the cheese or filter the 
coagulated milk, etc. No heat should be applied, and undue ex- 
posure to air should be avoided by using stoppered bottles. Make 
the filtered fluid faintly alkaline with sodium carbonate, and well 
shake with half its bulk of ether. Allow the perfectly clear ethereal 
solution to evaporate spontaneously ; and, if necessary, again ex- 
tract this aqueous residue with water, shaking with ether and evap- 
orating as before. The resulting residue may be tested in two or 
three ways. A little placed on the tongue and swallowed will cause 
more or less of nausea, vomiting, purging, and headache. Again, 
the residue is either characteristically crystalline or will become so 
after standing in a vacuum over sulphuric acid. Mix two or three 
drops of sulphuric acid and carbolic acid on a white plate, and add 
a few drops of the aqueous residue just mentioned ; if an orange-red 
or purple color results, the presence of tyrotoxicon may be suspected, 
but any nitrate or nitrite present may cause a similar color. To 
some of the aqueous residue add an equal volume of a saturated 
solution of caustic potash ; the double potassium and diazobenzene 
hydrate is then formed, and appears in six-sided plates, whereas any 
potassium nitrate appears in prisms. This residue may be treated 
with absolute alcohol, filtered, and the filtrate evaporated, when the 
plates may again be observed or the color reaction again obtained 
with this purified product (Vaughan). 

Obscure Poisons. — Many substances, the active principles of which 
are at present beyond the reach of the chemical analyst, are poisons 
of a more or less active character. (See the Pharmaceutical Journal 
for Sept. 6, 1879, p. 195, and for Dec. 20, 1879, p. 481.) 

" Chloral Hydrate," p. 486, and " Chloroform," p. 399, are now 



572 MORBID URINE. 

included in " Part 2 of Schedule A " as " poisons within the mean- 
ing of the Pharmacy Act, 1868." " Cantharides" is in " Part 1." 
Its active principle is isolated as described on p. 422, and is recog- 
nized by its blistering action on any thin spot on one's skin. 



ANTIDOTES.— Vide " Antidotes " in the Index. 



QUESTIONS AND EXERCISES. 

In examining food and similar matter for poison, why must not the 
ordinary tests for the poison be at once applied ? — What preliminary 
operations should be performed on a vomit in a case of suspected poison- 
ing ? — How would you search for corrosive sublimate in wine ? — By what 
series of operations would you satisfy yourself of the presence or absence 
of arsenic in the contents of the stomach ? — Describe the treatment to 
which decoction of coffee should be subjected in testing it for tartar 
emetic. — State how the occurrence of lead in water is demonstrated. — 
Give a process for the detection of copper in jam. — How would you de- 
tect zinc in a vomit ?— How may the presence of much sulphuric acid in 
gin be proved ? — In testing ale for nitric acid what reactions would you 
select? — Show how you would conclude that a dangerous quantity of 
hydrochloric acid had been added to cider. — Describe the manipulations 
necessary in testing for hydrocyanic acid in the contents of a stomach. 
— By what method is oxalic acid discovered in infusion of coffee ? — How 
is phosphorus detected in organic mixtures ?— Give the process by which 
strychnine is isolated from a vomit. — Mention the experiments by which 
the presence of laudanum in porter is demonstrated. — Name the anti- 
dotes in cases of poisoning by — a, alkaloids ; b, antimonials ; c, arsenic ; 
d, barium salts ; e, copper compounds ; /, hydrochloric acid ; g, hydro- 
cyanic acid ; h, lead salts ; i, corrosive sublimate ; j, nitric acid ; k, oxalic 
acid ; I, silver salts ; m, oil of vitriol ; n, tin liquors ; o, zinc salts ; p, car- 
bolic acid. 



EXAMINATION OF MORBID URINE AND 
CALCULI. 

The various products of the natural and continuous decay of ani- 
mal tissue and the refuse matter of food are eliminated from the 
system chiefly as fgeces, urine, and expired air. Air exhaled from the 
lungs carries off from the blood much carbon (about eight ounces in 
twenty-four hours) in the form of carbonic acid gas, and some aqueous 
vapor— the latter, together with a small amount of oily matter, also 
escaping by the skin. Directing the breath to a cold surface renders 
moisture evident, and breathing through a tube into lime-water 
demonstrates the presence of a considerable quantity of carbonic 
acid gas. The faeces consist mainly of the insoluble debris of the 
system, the soluble matters and water forming the urine. These 
excretions vary considerably, according to the food and general 
habits of the individual and external temperature. But in disease 
the variations become excessive ; hence their detection by the medi- 
cal practitioner, or by the pharmacist for the medical man, is a 
matter of importance. 



ALBUMEN. 573 

An analysis of faeces or air cannot be made with sufficient ease and 
rapidity to be practically available in medical diagnosis. But with 
regard to urine, certain abnormal substances and abnormal quan- 
tities of normal constituents may be chemically detected in the 
course of a few minutes by any one having already some knowledge 
of chemical manipulation. 

Healthy human urine contains, in 1000 parts, 957 of water, 14 of 
urea, 1 of uric acid, 15 of other organic matter, and 13 of inorganic 
salts. The amount passed in twenty-four hours varies from two to 
three pints in an adult, and its specific gravity, if healthy, will 
range from 1.015 to 1.025. Any considerable deviation from these 
limits would suggest a possibly pathological condition. The aver- 
age amount of solid matter passed by the urine in one day is 1 J to 2 
ounces. 

Physical Examination of Urine. 

Normal urine is either of a pale-yellow color or faintly reddish- 
yellow, due to a pigment termed urobilin. Urine has a reddish- 
brown tint if blood is present or greenish- brown if bile is present. 
Both color and odor are much influenced by certain kinds of food 
and by some drugs. 

Fresh urine is clear. Any turbidity may be due to urates, phos- 
phates, or pus. Urates redissolve when the urine is warmed, phos- 
phates by the addition of acetic acid ; pus is detected by the micro- 
scope {vide infra).. If the urine be turbid from the presence of phos- 
phates when first voided, it may be due to conversion of urea into 
ammonium carbonate, which precipitates the phosphates within the 
bladder, in which case the fresh and warm urine will effervesce 
slightly on the addition of acetic acid. This condition is abnormal. 

On standing, healthy urine commonly gives a slight cloud of 
mucus, and after severe exercise or after a hearty nitrogenous 
meal may give a sediment of urates. 

The specific gravity of urine should be taken on a specimen 
removed from the whole bulk excreted in twenty or twenty-four 
hours. Many qualitative experiments and all quantitative opera- 
tions should only be performed on the mixed urine of twenty-four 
hours. 

Healthy urine when fresh is always slightly acid, the acidity 
being said to be due to the presence of acid sodium phosphate. 
Alkalinity is probably due to that conversion of urea into ammo- 
nium carbonate within the bladder already described. 



EXAMINATION OF MORBID URINE FOR ALBUMEN, SUGAR, BILE, 
EXCESS OF UREA, OR DEFICIENCY OF CHLORIDES ; AND 
URINARY SEDIMENT FOR URATES (OR LITHATES), PHOS- 
PHATES, CALCIUM OXALATE, AND URIC ACID. 

Albumen. — To detect albumen, acidulate a portion of the 
clear urine in a test-tube with a few drops of diluted nitric acid 
(to keep phosphates in solution), and boil ; flocks or coagula 

25* 



574 MORBID URINE. 

will separate if albumen be present. To detect small quan- 
tities, nearly fill a long test-tube with clear urine (filtered, if 
necessary) and faintly acidulated with acetic acid ; then, hold- 
ing the tube by its lower end, boil the upper portion of the 

urine. A cloudiness in the boiled portion, which, on addition 

of a few drops of acetic acid, does not disappear, indicates the 
presence of albumen. Or heat a little nitric acid in a test- 
tube, and carefully pour down the side a little of the urjne, so 
as to overlie the acid. If albumen be present, a whitish ring 
or coagulum will, sooner or later, be formed at the junction of 
the fluids. 

These experiments should first be made on normal urine contain- 
ing a drop or two of solution of white of egg. The coagulum is 
white if it is only albumen, greenish if bile-pigment be present, and 
brownish-red if the urine contain blood. The influence of acids and 
alkalies on the precipitation of albumen is noticed on p. 545. 

A saturated solution of picric acid at once precipitates any albu- 
men from urine. Should the urine be alkaline, it must be acidified 
before applying this test. On warming the mixture the precipitate 
will become more pronounced if due to the albumen or globulin of 
blood or to any modifications of albumen caused by acidity or alka- 
linity of urine, but will disappear if due to peptone or pro-peptone. 
Potassium ferrocyanide also will precipitate the former varieties of 
albumen, but not the peptones. 

The occurrence of albumen in the urine may be temporary and of 
but little importance, or it may indicate the existence of a serious 
affection known as Bright 1 s disease. u Albumenuria is rarely a 
serious condition unless it is sufficiently pronounced to be made out 
by the cold nitric-acid test" (Steward). 

For quantitative purposes Esbach employs the picric test, dissolv- 
ing 10 parts of picric acid and 20 of citric acid in 900 of water by 
aid of heat, and, when the solution is cold, diluting with water to 
1000 parts. This solution is added to a given volume of urine in 
a graduated Cetti's Esbach tube, and the height of the precipitate is 
noted after twenty-four hours. Johnson finds a simple solution of 
5 grains of picric acid in 1 fluidounce of water better than Esbach' s 
solution, because the excess of acid in the latter tends to precipitate 
much uric acid which would be reckoned as albumen. A standard 
value is given to the solution in the first instance by washing, dry- 
ing, and weighing the albumen. 

Sugar. — To a portion of the clear urine in a test-tube add 
five or ten drops of solution of copper sulphate ; pour in solu- 
tion of potash or soda until the precipitate first formed is redis- 
solved ; slowly heat the solution to near the boiling-point ; a 
yellow, yellowish-red, or red precipitate (cuprous oxide) is 
formed if sugar be present. (The production of a rose-red or 
pink tint with the cold alkaline copper solution indicates the 



UREA. 575 

presence of the altered non-coagulable albumenoids termed 
peptones.) 

This experiment should be first made on urine containing a drop 
or two of solution of grape-sugar (p. 468). The copper hydrate pre- 
cipitated by the alkali is insoluble in excess of pure potash or soda, 
but readily dissolves if organic matter, especially sugar, be present. 
The copper salt should not contain iron. 

Other tests may be applied if necessary. ( Vide p. 470. See also 
" Sugar, Quantitative Estimation of," in Index.) 

A minute amount of sugar is said to occur in normal urine, and a 
distinct trace is occasionally present. In searching for small quanti- 
ties, uric acid, which also reduces the copper solution, should first 
be removed. (See p. 361.) Normal urine rotates a ray of plane 
polarized light slightly to the left, but if even a small amount of 
sugar be present marked dextrorotation results. In larger quanti- 
ties (often 5 per cent.) sugar is a characteristic constituent of the 
urine of diabetic patients, greatly increasing the specific gravity of 
the secretion. Small hydrometers (termed urinometers) are com- 
monly employed for quickly and readily ascertaining the specific 
gravity of urine ; they range from 1.000 to 1.050, the interval of 
1.015 to 1.025 being marked as " h. s." or " healthy state." (Vide 
"Specific Gravity" and "Hydrometers" in Index 5 also " Sugar, 
Quantitative Estimation of.") 

Bile. — This is detected by the dark greenish-brown color of the 
urine and by the general test (Pettenkofer's, or, still better, Quin- 
lan's) described on p. 552. Or a little of the urine may be placed 
on a white plate, and strong nitric acid, containing some nitrous 
acid, dropped on it ; a peculiar play of colors — green, yellow, violet, 
etc. — occurs if (the coloring-matter of) bile be present (Gmelin). 
In doubtful cases the urine should be thoroughly shaken up with a 
little chloroform, which dissolves the bile-pigments, and the acid 
test applied to the separated chloroform. Oliver recommends that 
the urine be diluted to a sp. gr. of 1.008, and then one volume be 
added to three volumes of the following reagent, when more or less 
opalescence will be produced, according to the amount of bile acids 
present. For the reagent dissolve 30 grains of flesh peptone, 4 
grains of salicylic acid, and 33 minims of official acetic acid in 8 
ounces of water ; filter. 

Excess of Uric Acid. — A rough quantitative process consists 
in applying the qualitative method already described (p. 361) 
to a known volume of urine, and collecting on a filter, washing, 
and weighing the resulting uric acid. The result is always 
low. Hopkins saturates the urine with ammonium chloride, 
and after a couple of hours decomposes the separated ammo- 
nium urate by hydrochloric acid, and collects, washes, dries, 
and weighs the resulting uric acid. (Vide Proceedings of the 
Royal Society, vol. lii. p. 93.) 

Excess of Urea. — About one-third of the solid matter in the 






576 MORBID URINE. 

urine is urea. Its proportion varies considerably, but 1J per 
cent, may be regarded as an average amount. Concentrate 
urine slightly by evaporation in a small dish, pour the liquid 
into a test-tube, set the tube aside till cold or coorit by letting 
cold water run over the outside, add an equal bulk of strong 
nitric acid, and again set aside ; scaly crystals of urea nitrate 
are deposited more or less quickly. 

With regard to the amount of urea in urine it is impossible to 
sharply define excess or deficiency. If nitric acid gives crystals 
without concentration, excess is certainly present in the sample 
examined, though, if the amount of urine passed in the twenty-four 
hours is much below the average, the quantity of urea excreted may 
not be abnormal. A rough estimate may be formed by mixing a 
few drops of the urine and acid on a piece of glass and setting aside ; 
the time which elapses before crystals form is an indication of the 
quantity in the specimen. The time will vary according to the 
temperature and state of moisture of the atmosphere, but with care 
some useful comparative results may in this way be obtained. 

For trustworthy quantitative estimations the urine is shaken with 
an alkaline solution of recently prepared sodium hypobromite, and 
the nitrogen then liberated collected and measured- The reaction 
is of the following character : 

CO(NH 2 ) 2 + 3NaBrO = 3NaBr + C0 2 -f 2H 2 + N 2 

Urea. Sodium Sodium Carbonic Water. Nitrogen, 

hypobromite. bromide. acid gas. 

The whole of the nitrogen of the urea, however, is not evolved, 
while, on the other hand, some of the produced nitrogen is yielded by 
the uric acid, hippuric acid, and creatinine of the urine. Neither 
fact is of any consequence in this examination of urine, for a given 
specimen of urine always yields the same quantity of gas ; hence a 
given volume of gas always indicates the same percentage of urea ; 
and once a measuring-tube is so divided as to indicate percentages 
of urea when a given volume of urine is used, it may be trusted to 
indicate the varying percentages of urea in the urine of one patient 
or the different proportions of urea in the urine of different patients. 
The method is Davy's, with improvements and modifications of 
apparatus by Knop, Huefner, Russell and West, Apjohn, Dupre, 
Gerrard, Gillet, and others. In the chemical laboratory appliances 
already at hand may be adapted for the operation. Thus, as shown 
in the woodcut on p. 577, any two-ounce or three-ounce bottle serves 
for the reaction between the hypobromite and urine ; a 50 or 60 cc. 
burette, containing water, may be the measuring-tube; while a 
funnel, supported in the ring of a retoTt-stand, serves both as a 
reservoir for water displaced by the evolved nitrogen and as a 
means of getting that equal level of water within and without the 
measuring-tube which shall prevent misleading attenuation or com- 
pression of the nitrogen. Attach the funnel to the bottom of the 
burette by india-rubber tubing. Attach a short glass tube by a 
pierced cork to the top of the burette, and by more india-rubber 



UREA. 



577 



Fig. 50. 




tubing connect this glass tube with a similar tube in the well-fitting 
india-rubber cork of the gas-generating bottle. Disconnect the latter. 
Into the funnel pour water until it rises to the zero-mark of the 
burette and a little water remains in 
the bottom of the funnel. Into the 
generating-bottle pour about 25 cc. of 
solution of soda (made by dissolving 
about 100 grms. of solid soda in 250 
cc. of water) and about 2.5 cc. of bro- 
mine. Into the bottle containing the 
hypobromite solution thus prepared a 
short test-tube containing 5 cc. of urine 
is lowered, care being taken that no 
urine is spilt. The cork is re-inserted 
and the water-level again adjusted (best 
accomplished if into the cork of the gen- 
erating bottle be fitted a short glass tube, 
the external orifice of which can be closed 
by a cork or a cap as soon as the appa- 
ratus is ready for use). The generat- 
ing bottle is now inclined, when, the 
urine and hypobromite mixing, nitro- 
gen is at once evolved (the carbonic 
acid produced at the same time being absorbed by the strongly 
alkaline fluid in the bottle). The funnel is lowered until the surfaces 
of the water inside and outside the measuring-tube are on a level ; 
after ten or fifteen minutes the level is finally adjusted and the 
amount of produced gas noted. Every 55 cc. of gas indicates 0.15 
of a grm. of urea, the temperature being about 66° F. and the height 
of the barometer being about thirty inches. In cases in which 
frothing interferes put a fragment of suet into the generating bottle. 

Instead of sodium hypobromite, the hypochlorite, which is more 
stable, may be employed (Squibb). 

Tests. — Urea in solution in water may be detected by the reaction 
with nitric acid, and by the readiness with which it yields ammonia 
on being boiled with alkalies. In putrid urine its conversion into 
an ammoniacal salt has already been effected by ammoniacal fer- 
mentation. 

CO(NH 2 ) 2 + 2H 2 = (NH 4 ) 2 C0 3 

Urea. Water. Ammonium carbonate. 

This transformation of the urea into ammonium carbonate is due 
to the action of a special ferment belonging to the genus Torula, 
formed of chaplets of globules similar in form to, but much smaller 
than, those of beer-yeast. It occurs as a white deposit in the urine. 
If some of this deposit be added to a saccharine solution containing 
urea, it rapidly multiplies, ammonium carbonate being formed. 

Formula of Urea. — The empirical formula of urea is CH 4 N 2 0. 
Its rational formula may be thus written : 

(CO)' 



co< 



NH 2 
NH 9 



N, 



578 MORBID URINE. 

that is, it may be regarded as carbamide or as one of the organic 
bases already referred to — a primary diamine, in which the bivalent 
radical CO occupies the place of H 2 . The other atoms of hydrogen 
may be displaced by various radicals, and many compound ureas 
thus be obtained. 

Artificial Urea. — Urea may be prepared artificially by Williams's 
modification of Wohler's method. Potassium cyanide of the best 
commercial quality (containing about 90 per cent, of real cyanide) 
is fused at a very low red heat in a shallow iron vessel ; red lead is 
added in small quantities at a time, the temperature being kept 
down by constant stirring. When the red lead ceases to cause 
further action, the mixture (lead and potassium cyanate) is allowed 
to cool, the product finely powdered, exhausted with cold water, 
barium nitrate added till no more precipitate (barium carbonate) 
falls, the mixture filtered, and the filtrate treated with lead nitrate 
$o long as lead cyanate is thrown down. The latter is thoroughly 
washed, and dried at a low temperature. Equivalent quantities of 
lead cyanate and ammonium sulphate, digested in a small quantity 
of water with a little heat {vide p. 339) and filtered, yield a solution 
from which urea crystallizes on cooling. 

Another Process. — Basaroff has found that urea is produced when 
ordinary ammonium carbonate is heated in strong hermetically 
sealed tubes to about 275° F. for a few hours. The same chemist 
had previously obtained urea by similarly heating pure ammonium 
carbamate ; so . that the source of the urea in the former case is 
probably the ammonium carbamate believed to occur in the car- 
bonate. (See p. 93.) 

NH 4 NH 2 C0 2 - H 2 = CO(NH 2 ) 2 . 

Deficiency of Chlorides. — Any given bulk of urine in a test-tube- 
yields, of course, abundance of flocks of silver chloride on the addi- 
tion of nitric acid and silver nitrate. Any markedly smaller bulk 
points to pathological conditions, such as those of acute fever. 

Chromogens. — Urine may contain chromogens, which are sub- 
stances which do not at the time color the urine, but which, on the 
addition of oxidizing reagents or after standing some time, develop 
a color. A blue color may be seen in urine on the addition of much 
nitric acid. This is due to the formation of indigo from its chro- 
mogen. The darkening often noticed on the addition of acid to 
urine is due to liberation of the pigment urobilin from its chromo- 
gen. Care must be taken not to confound the color-changes in 
urine due to the action of drugs with the effects produced by the 
action of oxidizing agents on chromogens. Thus rhubarb and san- 
tonin darken the natural yellow of urine, the addition of an alkali 
causing a red coloration. Carbolic acid taken internally makes the 
urine greenish-black, resembling urine with much bile in it. If 
potassium iodide or bromide is being taken internally, the addition 
of a strong acid will often cause separation of iodine or bromine, 
respectively, in the urine. 



URINARY SEDIMENTS. 



579 



Urinary Sediments. 
Warm the sediment with the supernatant urine, and filter. 



Insoluble. 

Phosphates, calcium oxalate, and uric acid. 
Warm with acetic acid, and filter. 



Insoluble. 


Soluble. 


Calcium oxalate and uric acid. 


Phosphates. 


Warm with hydrochloric acid, 


Add ammo- 


filter. 


nia ; white 




ppt. = cal- 


Insoluble. 


Soluble. 


cium phos- 
phate or 


Uric acid. 


Calcium oxal- 


a m m o n 1 o- 


Apply the mu- 


ate. 


magnesium 


rexid test (p. 


May be repre- 


phosphate, 


362). 


cipitated by 
ammonia. 


or both. 



Soluble. 

Ammonium, 
calcium, or so- 
dium urates ; 
chiefly the 
latter. 

They are rede- 
posited as the 
liquid cools, 
and if suf- 
ficient in 
quantity may 
be further ex- 
amined for 
ammonium, 
calcium, so- 
dium, and the 
uric radical 
by the appro- 
priate tests. 



Notes. — Urinary deposits are seldom of a complex character : the 
action of heat and acetic arid hydrochloric acids generally at once 
indicates the character of the deposit, rendering filtration and pre- 
cipitation unnecessary. 

The Urates are often of a pink or red color, owing to the presence 
of a pigment termed purpurin ; hence the common name of red 
gravel for such deposits. Purpurin is soluble in alcohol, and may 
be removed by digesting a red deposit in that solvent. It is seldom 
necessary to determine whether the urate be that of ammonium, 
calcium, or sodium. (See, also, Uric Acid, p. 368.) The deposited 
urate is a very acid urate, which slowly (more rapidly in urine 
diluted with water) breaks up into a less acid urate and uric acid 
(Bence Jones). The occurrence in the urine of the salines of our 
food, especially of dipotassic phosphate, is apparently (Roberts) 
what prevents this decomposition before the urine is exposed to the 
air. 

Calcium phosphate and ammonio-magnesium phosphate are usually 
both present in a phosphatic deposit, the magnesium salt forming 
the larger proportion. They may, if necessary and if sufficient in 
quantity, be separated by collecting on a filter, washing, and boiling 
with solution of sodium carbonate. The calcium and magnesium 
carbonates thus formed are collected on a filter, washed, and dis- 
solved in a drop or two of hydrochloric acid ; ammonium chloride, 
ammonia, and ammonium carbonate are added, and the mixture 
boiled and filtered ; any calcium originally present will then remain 



580 MORBID URINE. 

insoluble as calcium carbonate ; while any magnesium will be pre- 
cipitated from the nitrate as ammonio-magnesium phosphate on the 
addition of sodium phosphate, the mixture being also well stirred. 

The chief portion of excreted phosphates is carried on 7 by the 

faeces, that remaining in the urine being kept in solution by the 

influence of acid sodium phosphate and, frequently, lactic acid. 

Occasionally, an hour or two after a hearty meal, the urine becomes 
sufficiently alkaline for the phosphates to be deposited, and the urine 
when passed is turbid from their presence. The ammoniacal con- 
stituent of the magnesium salt does not occur normally, but is pro- 
duced from urea as soon as urine becomes alkaline. 

Calcium oxalate is seldom met with in excessive amounts, but 
very often in small quantities mixed with phosphates. In one case 
of oxaluria the whole urine excreted by a patient in twenty-four 
hours furnished to the author only two-thirds of a grain of calcium 
oxalate. 

Free uric acid is in most cases distinctly crystalline, and nearly 
always of a yellow, red, or brown color. 

Artificial Sediments. — For educational practice these may be 
obtained as follows : 1. Rub up in a mortar a few grains of serpent's 
excrement (chiefly ammonium urate) with an ounce or two of urine ; 
this represents a sediment of urates. 2. Add a few drops of solu- 
tion of ammonia or solution of ammonium carbonate to urine ; the 
deposit may be regarded as one of phosphates. 3. To an ounce or 
two of urine add very small quantities of calcium chloride and 
ammonium oxalate ; the precipitate is calcium oxalate. 4. To urine 
acidulated by hydrochloric acid add a little serpent's excrement; 
the sediment is uric acid. 

Other deposits than the foregoing are occasionally observed. 
Thus, Mppuric acid (HC 9 H 8 N0 3 ), a normal constituent of human 
urine and largely contained in the urine of herbivorous animals, is 
sometimes found associated with uric acid in urinary sediment, 
especially in that of patients whose medicine contains benzoic acid 
(p. 340). Its appearance, as observed by aid of the microscope, is 
characteristic — namely, slender, four-sided prisms having pointed 
ends. Cystin, C 3 H 7 NS0 2 (from Kvartg, kustis, a bladder, in allusion 
to its origin), rarely occurs as a deposit in urine. It is not soluble 
in warm urine or dilute acetic acid, and scarcely in diluted hydro- 
chloric acid ; hence would be met with in testing for free uric acid. 
It is very soluble in ammonia, recrystallizing from a drop of the 
solution placed on a piece of glass in characteristic microscopic six- 
sided plates. Leucine and tyrosine (see p. 513) occur in cases of 
phosphorus-poisoning and of acute yellow atrophy of the liver. 
Organized sediments may be due to the corpuscles of pus, mucus, 
or blood, fat-globules, spermatozoa, cylindrical casts of the tubes of 
the kidneys, epithelial cells from the walls of the bladder, or foreign 
matters, such as fibres of wool or of cotton or wood, small feathers, 
dust, starch, etc. ; these are best recognized by the microscope. 
(See the accompanying figures and the following paragraphs on the 
microscopic appearances of both crystalline and organized urinary 
sediments*) 



URINARY SEDIMENTS. 



581 



Microscopic Examination of Urinary Sediments. 

Urine containing insoluble matter is usually more or less opaque. 
For microscopical examination a few ounces should be set aside in 
a conical test-glass for an hour or two, the clear supernatant urine 
poured off from the sediment as far as possible, a small drop of the 
residue placed on a slip of glass and covered with a piece of thin 
glass, and examined under the microscope with different magnifying 
powers. 

The respective appearances of the various crystalline and organ- 
ized matters are given in Figs. 51-62, which were kindly drawn by 
the late H. B. Brady, F. R. S., from natural specimens in the collec- 
tions of St. Bartholomew's Hospital, Dr. Sedgwick, the late Mr. W. 
W. Stoddart, Mr. Waddington, and the author. 

Uric acid occurs in many forms, most of which are given in Figs. 
51 and 52. Flat, more or less oval crystals, sometimes attached to 
each other, their outline then resembling an 8, a cross, or a star, 
are common. Single and grouped quadratic prisms, aigrettes, 
spiCula, and crystals recalling dumb-bells are met with. From urine 



Fig. 51. 







Uric Acid. 



Uric Acid. 



acidulated by hydrochloric acid square crystals, two opposite sides 
smooth and two jagged, are generally deposited ; acidulated by 
acetic acid, more typical forms are obtained. A drop of solution 
of potash or soda placed on the glass slip will dissolve a deposit of 
uric acid, a drop of any acid reprecipitating it in minute but charac- 
teristic crystals. 

Cystin is very rarely met with as an urinary deposit ; that from 
which Fig. 53 was taken was found in the urine of a patient in St. 
Bartholomew's Hospital. Lamellas of cystin always assume the 
hexagonal character, but the angles are sometimes ill defined and 
the plates superposed : in the latter case a drop of solution of 
ammonia placed on the glass at once dissolves the deposit, well- 
marked six-sided crystals appearing as the drop dries up. 

Triple phosphate (magnesium and ammonium phosphate) is de- 



582 



MORBID URINE. 



posited as soon as urine becomes alkaline, the ammoniacal constit- 
uent being furnished by the decomposition of urea. It occurs in 
large prismatic crystals, forming a beautiful object when viewed by 

Fig. 53. 




mm 1 



Cystin. 



Triple Phosphate. 



polarized light — sometimes also in ragged stellate or arborescent 
crystals, resembling those of snow. Both forms may be artificially 
prepared by adding a small lump of ammonium carbonate to a few 
. ounces of urine and setting aside in a test-glass (Fig. 54). 

Amorphous deposits are either earthy phosphates (a mixture of 
magnesium and calcium phosphates) or calcium, magnesium, ammo- 
nium, potassium, or sodium urates — chiefly the latter. They may 
be distinguished by the action of a drop of acetic acid placed near 
the sediment on the glass slip, the effect being watched under the 
microscope ; phosphates dissolve, while urates gradually assume 
characteristic forms of uric acid. Urates redissolve when warmed 
with the supernatant urine. 

Sodium and magnesium urates, though generally amorphous, 
occasionally take a crystalline form — bundles or tufts of small 
needles — as shown in Figs. 55 and 56. When pink or brick-red 
the color is due to uroerythrin. 

Calcium oxalate commonly occurs in octahedra, requiring high 
magnifying power for their detection. The crystals are easily over- 
looked if other matters are present, but are more distinctly seen 
after phosphates have been removed by acetic acid. In certain 
aspects the smaller crystals look like square plates traversed by a 
cross. A dumb-bell form of this deposit is also sometimes seen, 
resembling certain forms of uric acid and the coalescing spherules 
of a much rarer sediment — calcium carbonate. Calcium oxalate is 
insoluble in acetic, but soluble in hydrochloric, acid. The octahedra 
are frequently met with in the urine of persons who have partaken 
of garden rhubarb and certain other vegetables. The crystals may 
often be deposited artificially (according to Waddington) by drop- 
ping a fragment of oxalic acid into several ounces of urine and set- 
ting aside for a few hours. 



URINARY SEDIMENTS. 



583 



Calcium carbonate is rarely found in the urine of man, but fre- 
quently in that of the horse and other herbivorous animals. Human 
urine containing calcium carbonate often reddens litmus-paper, and 
it is only after the removal, on standing, of the excess of carbonic 



Fig. 55. 



56. 









Urates. 

a, of Sodium ; )- Calcium Oxalate. 

b, of Magnesium. 



8 , * K 



Calcium Carbonate. Hippuric Acid. 



acid that the salt is deposited. It consists of minute spherules, 
varying in size, the smaller ones often in process of coalescence. 
The dumb-bell form thus produced is easily distinguished from simi- 
lar groups of uric acid or calcium oxalate by showing a black cross 
in each spherule when viewed by polarized light. Acetic acid dis- 
solves calcium carbonate, liberating carbonic acid gas, with visible 
effervescence (under the microscope) if the slide has been previously 
warmed and a group of crystals be attacked. 

Hippuric Acid. — The pointed rhombic prisms and acicular crys- 
tals are characteristic and easily recognized. The broader crystals 
may possibly be mistaken for triple phosphate, and the narrower 
for certain forms of uric acid ; but insolubility in acetic acid dis- 
tinguishes them from the former, and solubility in alcohol from the 
latter. These tests may be applied while the deposit is under micro- 
scopic observation. An alcoholic solution of hippuric acid, evap- 
orated to dryness and the residue treated with water, gives a solution 
from which characteristic crystalline forms of hippuric acid may be 
obtained on allowing a drop to dry up on a slip of glass. 

The organized deposits in urine entail greater care in their deter- 
mination, and usually require a higher magnifying power for their 
proper examination, than those of crystalline form. The figures 
are drawn to 230 diameters. The following note will assist the 
observer : 

Casts of uriniferous tubuli are fibrinous masses of various forms, 
and often of considerable length — sometimes delicate and trans- 
parent, occasionally granular, and often beset with fat-globules. 
Epithelial debris is frequently present in urine in the form of 



584 



MORBID URINE. 



nucleated cells, regular and oval when full, but angular and un- 
symmetrical when partially emptied of their contents — sometimes 
perfect, but more frequently a good deal broken up. Casts are 
very readily discovered by the use of the microscope if, to a sample 



Fig. 57. 



Fig. 58. 




Epithelial Cells and Tubuli 



Blood-corpuscles. 



of the urine supposed to contain them, best in a conical glass, a 
few drops of an aniline dye be added. " Carbo-fuchsine " answers 
well. The casts rapidly stain, and are then quite easily seen in the 
field (Fig. 57). 

Blood is easily recognized. Urine containing it is usually high- 
colored or " smoky," and the corpuscles appear under the microscope 
as reddish circular disks, either single or laid together in strings re- 
sembling piles of coin (Fig. 58). Their color and somewhat smaller 
size serve to distinguish them from pus-corpuscles. In doubtful cases 
a minute drop of blood taken from a finger by help of a needle 
should be diluted with water and used for comparison. After urine 
containing blood has stood for some time, the corpuscles lose their 
regular rounded outline and become crenated. (See a in Fig. 58.) 

Dr. Day of Geelong tests for blood in urine or in stains on 
clothing by employing a recently-prepared alcoholic solution of 
the inner unoxidized portions of guaiacum resin and an aqueous 
or ethereal solution of hydrogen peroxide, when a dull-blue color 
results. In the case of urine add to a drachm or two in a test-tube 
nearly as much of the ethereal fluid, and then two or three drops 
of the guaiacum tincture ; on gently agitating the tube a bluish- 
green layer appears at the junction of the fluids if blood is present. 
" If the stain is on a dark-colored fabric, the parts moistened by 
the fluids may be pressed with white blotting-paper, when blue 
impresssions will be obtained. Contact with many substances 
causes the blue reaction or oxidation of guaiacum : the peculiarity 
of blood is that it does not produce this effect unless hydrogen per- 
oxide or a similar ' antozonic ' liquid is present. Bodies such as 
potassium permanganate, whose oxygen is apparently in the form 



URINARY SEDIMENTS. 



585 



of ozone, also cause the production of a blue color with guaiacum ; 
hydrogen peroxide and other compounds whose oxygen is in the 
opposite, positive, or, according to Schonbein, antozonic condition, 
produce no such eifect. It would seem as if blood or some con- 
stituent of blood has the power of converting positive into negative 
oxygen, and thus bringing about an effect which negative oxygen 
alone is able to produce ; for of all substances which, like blood, do 
not alone cause guaiacum to become blue, blood is the only one that 
so affects ' antozonides ' (themselves inactive) as to enable them to 
act as ozonides ; that is, to oxidize the guaiacum. Both the venous 
and the arterial fluid from any red-blooded animal will produce this 
blue reaction. Fruit-stains are darkened by ammonia, which does 
not alter the color of blood. Iron stains or iron moulds yield no 
color to water, whereas the red coloring-matter of blood is soluble 
in water. The hydrogen peroxide should be free from more than 
a trace of acid." 

The blood-corpuscles of ordinary animals are much smaller than 
those of man, but a -^ or -^ inch lens is necessary for proper differ- 
entiation (J. G. Richardson). 

Pus and Mucus. — Purulent urine deposits, on standing, a light- 
colored layer, easily diffused through the liquid by shaking. Acetic 
acid does not dissolve the sediment, and solution of potash of official 
strength converts it into a gelatinous mass. Under the microscope 
pus-corpuscles appear rounded and colorless, rather larger than 
blood-disks, and somewhat granular on the surface. They generally 



Fig. 59. 



Fig. 60. 




Pus-corpuscles. 



Fat-globules. 



show minute nuclei, which are more distinctly seen after treatment 
with acetic acid. (See the portion of Fig. 59 marked a.) Mucus 
possesses no definite microscopic characters, but commonly has 
imbedded in it pus, epithelium, and air-bubbles. Mucus is coag- 
ulated in a characteristic manner by acetic acid ; and this reaction, 
together with the ropy appearance it imparts to urine, prevents it 
being confounded with pus. 



586 



MORBID URINE. 



Day's test for pus consists in adding a drop or two of oxidized 
tincture of guaiacum to the urine or other liquid, when a clear blue 
color is produced. It is necessary to moisten dry pus with water 
before applying the test. The test-liquid is made by exposing 
a saturated alcoholic solution of guaiacum to the air until it has 
absorbed a sufficient quantity of oxygen to give it the property of 
turning green when placed in contact with potassium iodide. Day's 
test for mucus consists in the application, first, of oxidized tincture 
of guaiacum, which by itself undergoes no change in the presence 
of mucus, and then in the addition of carbolic acid or creasote, 
which quickly changes the color of the guaiacum to a bright blue. 
Neither carbolic acid nor creasote alone will render guaiacum blue. 
In testing for mucus on cloths or when it is mixed with blood, it is 
necessary to use the carbolic acid pure 5 but when the mucus is in 
a liquid state, it is better to use carbolic acid diluted with alcohol. 

Saliva. — This secretion is an aqueous fluid containing less than 
1 per cent, of solid matter, of which one-third is an albumenoid 
substance termed ptyalin (from nrvalov, spittle), a ferment that has 
the power of converting starch into dextrin and grape-sugar : 
alkaline salts, including a trace of potassium sulphocyanate, and 



Fig. 61. 



Fig. 62. 




Spermatozoa. 



Sarcina ventriculi. 



calcium compounds, are also present. Day's test for saliva in urine, 
etc. is similar to that for mucus, with the exception that the blue 
reaction produced by the oxidized tincture of guaiacum and alcoholic 
solution of carbolic acid is highly intensified by the addition of 
a little ethereal or aqueous solution of hydrogen peroxide. 

Fatty matter | occurs either as minute globules partially diffused 
through the urine (as shown at a) or in more intimate emulsion (as 
at b in Fig. 60). When present in larger quantity it collects as 
a sort of skim on the surface after standing. 

_ Spermatozoa are liable to escape notice on account of their small 
size and extreme transparency. Suspected urine should be allowed 
to settle some hours in a conical test-glass, and the drop at the 



URINARY CALCULI. 587 

bottom examined under a high power. The drawing (Fig. 61) 
shows their tadpole-like appearance. 

Sarcince rarely occur in urine, but are not infrequent in vom- 
ited matters. The upper figures (a, Fig. 62) are copied from Dr. 
Thudichum's drawing (from urine) ; the larger groupings (b) are 
from vomited matter. 

Extraneous bodies, such as starch, hair, wool, fibres of cotton 
or of deal, or fragments of feathers, are often found in urinary 
deposits, and ludicrous mistakes have been made by observers not 
on their guard in respect to such casual admixtures. 

Examination of Urinary Calculi. 

The term calculus is the diminutive of calx, a lime- or chalk- 
stone. 

The following calculi have been met with : (1) Uric acid, (2) 
sodium urate, (3) calcium oxalate (mulberry), (4) fusible or mixed 
calcium and triple phosphates, (5) calcium phosphate, (6) calcium 
carbonate, (7) xanthine, (8) cystin, (9) urostealith (fatty matter), 
(10) indigo (one case). 

Knowledge of the composition of a calculus or urinary deposit 
affords valuable diagnostic aid to the physician ; hence the import- 
ance of a trustworthy analysis of these substances. 

Nature of Calculi. — Urinary calculi have the same composition 
as unorganized urinary sediments. They consist, in short, of 
sediments that have been deposited slowly within the bladder, 
particle on particle, layer on layer, the several substances becoming 
so compact as to be less easily acted on by reagents than when 
deposited after the urine has been passed — the urates less readily 
soluble in warm water, the calcic phosphate insoluble in acetic acid 
until it has been dissolved in hydrochloric acid and reprecipitated by 
an alkali. 

Preliminary Treatment. — If the calculus is whole, saw it in two 
through the centre, and notice whether it is built up of distinct 
layers or apparently consists of one substance. . If the latter, use 
about a grain of the sawdust for analysis ; if the former, carefully 
scrape off portions of each layer and examine them separately. If 
the calculus is in fragments, select fair specimens of about half 
a grain or a grain each, and reduce to a fine powder by placing on 
a hard surface and crushing under the blade of a knife. 

Analysis. — Commence the analysis by heating a portion, 
about the size of a pin's head, on platinum -foil, in order to 
ascertain whether organic matter, inorganic matter, or both, are 
present. If both, the ash is examined for inorganic substances, 
and a fresh portion of the calculus for uric acid by the murexid 
test. (In the absence of uric acid any slight charring may be 
considered to be due to indefinite animal matter.) If com- 
posed of organic matter only, the calculus will in nearly all 
cases be uric acid, the indication being confirmed by applying 
the murexid test in a watch-glass to another fragment half the 



588 



MORBID URINE. 



size of a small pin's head. If inorganic only, the ash on the 
platinum-foil may be examined for phosphates, and a separate 
portion of the calculus for oxalates. Even a single drop of 
liquid obtained in any of these experiments may be filtered by 
placing it on a filter not larger than a sixpence and previously 
moistened with water, and adding three or four drops of water, 
one after the other, as each passes through the paper ; or a 
drop of mixture may be placed on a fragment of damped filter- 
paper on a glass slide, the latter then tilted, and a clear drop 
be drained off from the paper on to the slide ready for the 
addition of a reagent. If the calculus is suspected to contain 
more than one substance, boil about half a grain of the pow- 
der in half a test-tubeful of distilled water for a few minutes 
and pour it on a small filter ; then proceed according to the 
following table : 



Insoluble. 

Phosphates, calcium oxalate, and free 

uric acid. 

Boil with two or three drops of hydrochloric 

acid, and filter. 


Soluble. 

Urates. 

These will probably 

be redeposited as 

the solution cools. 

Small quantities 


Insoluble. 

Uric acid. 

Apply the 
murexid 
test (p. 


Soluble. 

Phosphates and calcium oxalate. 

Add excess of ammonia, and then 

excess of acetic acid; filter. 


may be detected 
b y evaporating 
the solution to 
dryness. They 
are tested for am- 
monium, sodium, 
calcium, and the 


362). 


Insoluble. 

Calcium 
oxalate. 


Soluble. 

Phosphates. 

They may be reprecip- 1 

itated by ammonia. 


uric radical by 
the appropriate 
reagents. 



Varieties of Calculi. — Calculi composed entirely of uric acid are 
common ; a minute portion heated on platinum-foil chars, burns, 
and leaves scarcely a trace of ash. The phosphates frequently occur 
together, forming what is known as the fusible calculus, from the 
readiness with which a fragment aggregates, and even fuses to a 
bead, when heated on a loop of platinum-wire- in the blowpipe 
flame. The phosphates may, if necessary, be further examined by 
the method described in connection with urinary deposits. Calcium 
oxalate often occurs alone, forming a dark-colored calculus having 
a very rough surface, hence termed the mulberry calculus. Smaller 
calculi of the same substance are called, from their appearance, 



OFFICIAL GALENICAL PREPARATIONS. 589 

hempseed calculi. Calculi of cystin are rarely met with. Xanthine 
(from tjavdbg, xanthos, yellow, in allusion to the color it yields with 
nitric acid) still less often occurs as a calculus. The earthy concre- 
tions, or " chalk-stones" which frequently form in the joints of gouty 
persons are composed chiefly of urates, the sodium salt being that 
most commonly met with. Gall-stones, or biliary calculi, occasionally 
form in the gall-bladder ; they contain cholesterin (from x°^V-, chole, 
bile, and crepebg, stereos, solid), a fatty substance of alcoholoid consti- 
tution, soluble in rectified spirit or ether, and crystallizing from such 
solutions in well-defined, square, scaly crystals. Phosphatic and 
other calculi of many pounds' weight are occasionally found in the 
stomach and larger intestines of animals. 



QUESTIONS AND EXERCISES. 

In breathing how much carbon (in the form of carbonic acid gas) is 
exhaled from the lungs every twenty-four hours ? — How may the pres- 
ence of carbonic acid gas in expired air be demonstrated ? — Mention an 
experiment showing the escape of moisture from the lungs during 
breathing. — State the method of testing for albumen in urine. — Give the 
tests for sugar in urine. — What is the average composition of healthy 
urine ? — Give the tests for urea. — Write the rational formulae of some 
compound ureas in which methyl or ethyl displaces hydrogen. — Describe 
an artificial process for the production of urea, giving equations. — 
Sketch out a plan for the chemical examination of urinary sediments. — 
A deposit is insoluble in the supernatant urine or in acetic acid ; of 
what substances may it consist ? — Which compounds are indicated when 
a deposit redissolves on warming it with the supernatant urine ? — Name 
the salts insoluble in warmed urine, but dissolved on the addition of 
acetic acid. — Mention the chemical characters of cystin. At what stage 
of analysis would it be recognized ? — Describe the microscopical appear- 
ances of the following urinary deposits : Uric acid, cystin, triple phos- 
phate, earthy phosphates, urates, calcium oxalate, calcium carbonate, 
hippuric acid, tube-casts, epithelial debris, blood, pus, mucus, fat, sperma- 
tozoa, sarcinse, extraneous bodies. — How are Day's tests for blood, pus, 
and saliva applied? — State the physical and chemical characters of 
urinary calculi. — How are urinary calculi prepared for chemical exami- 
nation ? — Draw out a chart for the chemical examination of urinary 
calculi. — Why is the " fusible calculus " so called ? and what is its compo- 
sition ? — State the characters of " mulberry " and " hempseed " calculi. — 
What are " chalk-stones " of gout, and " gall-stones," or " biliary calculi " ? 



THE GALENICAL PREPARATIONS OF THE 

PHARMACOPEIAS. 

The preparation of Cerates, Confections, Decoctions, Enemas, 
Extracts, Glycerins, Infusions, Inhalations, Juices, Liniments, 
Lozenges, Mixtures, Ointments, Pills, Plasters, Poultices, 
Powders, Spirits, Suppositories, Syrups, Tinctures, and Wines 
includes a number of mechanical rather than chemical opera- 
tions, and belongs to the domain of pure Pharmacy. The 
medical or pharmaceutical pupil will probably have had some 

26 






590 OFFICIAL GALENICAL PREPARATIONS. 

opportunity of practically studying these compounds before 
working at experimental chemistry, and may have prepared 
many of them according to the directions of the pharmaco- 
poeias ; if not, he is referred to the pages of the last edition of 
those works for details. 

Among the extracts of the British Pharmacopoeia, however, 
there are five (namely, those of aconite, belladonna, hemlock, 
henbane, and lettuce) which are not simply evaporated infu- 
sions, decoctions, or tinctures, like most others, but are evap- 
orated juices from which vegetable albumen, the supposed 
source of fermentation and decay, has been removed, and chlor- 
ophyll (the green coloring-matter of plant-juice) retained, prac- 
tically unimpaired in tint. For educational practice either of 
the above-named five raw materials may be employed ; but in 
order that attention may be concentrated on the process by 
which the. extracts are prepared, rather than on any one of the 
extracts themselves, it suffices to make an extract of some 
ordinary green vegetable, such as cabbage or turnip-tops. 
Bruise the green leaves of a good-sized cabbage in a mortar, 
and press out the juice ; heat it gradually to 130° F. and 
remove the green flocks of chlorophyll which separate by filtra- 
tion through calico. When the liquor has all passed through 
the filter, set the chlorophyll aside for a time, heat the strained 
liquor to 200° F. to coagulate albumen ; remove the latter by 
filtration and throw it away ; evaporate the filtrate on a water- 
bath to the consistence of thin syrup ; then add to it the chloro- 
phyll, first passing the latter through a hair sieve to break up 
clots, and, stirring the whole together assiduously, continue the 
evaporation at a temperature not exceeding 140° F. until the 
extract is of a suitable consistence for forming pills. A higher 
temperature than that indicated would cause the alteration of 
the chlorophyll to a dark-brown substance, any such extract 
used in pharmacy no longer having the green tint which cus- 
tom and the British Pharmacopoeia demand. 



QUESTIONS AND EXERCISES. 

Enumerate the different classes into 1 which official galenical prepara- 
tions may he divided. — Describe the general process for the preparation 
of green extracts — aconite, belladonna, hemlock, henbane, lettuce. — Why- 
is vegetable albumen excluded in the preparation of green extracts ? — 
How may chlorophyll be removed from vegetable juices, and again be 
introduced into their evaporated residues without destroying its color? 
— For what reason is exposure of chlorophyll to a boiling temperature 
avoided in the manufacture of green extracts? 



OFFICIAL CHEMICAL PREPARATIONS. 591 



THE CHEMICAL PREPARATIONS OF THE 
PHARMACOPOEIAS. 

The process by which every official chemical substance is 
prepared has already been described, and the strictly chemical 
character of the processes illustrated by experiments and ex- 
plained by aid of equations. Should the reader, in addition, 
desire an intimate acquaintance with the details of manipula- 
tion on which the successful and economic manufacture of 
chemical substances depends, he is advised to prepare, if he 
has not done so already, a few ounces of each of the salts 
mentioned in the pharmacopoeias or commonly used in phar- 
macy. An additional guide in these operations will be the 
pharmacopoeias themselves. 

The production of many chemical and galenical substances 
on a commercial scale can only be successfully carried on in 
manufacturing laboratories and with some knowledge of the 
circumstances of supply and demand, value of raw material 
and by-products, etc. ; for the technical preparation of such 
substances requires much knowledge beyond even a thorough 
acquaintance with chemistry. Still, in the present day, com- 
mercial chemistry and pharmacy can best hope for success 
when founded on the working out of abstract scientific prin- 
ciples. The problem of manufacturing success is now only 
solved with certainty by sound and wisely-applied science. 



Memorandum. — The next subjects of experimental study will 
be determined by the nature of the student's future pursuits. In 
most cases the operations of quantitative analysis will engage 
attention. These should be of a volumetric and gravimetric 
character ; for details concerning them see the following pages. 



QUANTITATIVE ANALYSIS. 

INTRODUCTORY REMARKS. 

General Principles. — The proportions in which chemical sub- 
stances unite with each other in forming compounds are definite and 
invariable (p. 48). Quantitative analysis is based on this law. 
When, for example, aqueous solutions of a salt of silver and a 
chloride are mixed, a white curdy precipitate is produced containing 
chlorine and silver in atomic proportions ; that is, 35.5 parts of 



592 QUANTITATIVE analysis. 

ohlorine bo L08 of silver. No matter what the ohloride or what the 
salt of silver, t ho resulting silver ohloride is invariable in OOmpOBi- 
tioii. The formula AgCl IS Q coin enienl picture of this com pound 

in these proportions. The weight o\' a definite oompound being 
givenj therefore, bhe proportional amounts of its constituents oan be 
asoertained by simple oaloulation. Suppose, for instanoe, 8.53 parts 
of silver ohloride have been obtained in some analytical operation: 
this amount will oontain 2.11 parts of ohlorine and 6,42 of silver. 

Foi if 1 13.5 (the molecular Weight) o\' silver chloride contain .">.">.."> 

(the atomio weight) of ohlorine, 8.58 of silver ohloride will he found 

to contain 'J. I I of chlorine : 

L43.5 : 35.5 i\ s.;>;> : x 
8.53 



L.065 
L7.75 
284.0 



l 13.5)302.815(2.11 

15.81 
14.35 



L.465 

L.435 *»2.1] 

And it" 1 13.5 of silver ohloride oontain L08 of silver, 8.53 of silver 
ohloride will contain 6.42 of silver, To ascertain, for example, the 

amount oi' silver in a suhstanee containing, sav, silver nitrate, all 

that |s uecessarv is to bake :» weighed quantity of the substance, 
dissolve it, precipitate bhe whole of the silver by adding hydroohlorio 

add Or Other ohloride till no more silver ohloride falls, collect the 

precipitate on a Biter, wash, dry, and weigh, The amount o\' silver 

in the dried chloride, ascertained hv calculation, is the amount o\' 

silver in bhe quantity of suhstanee on which the operation was con 
ducted j a mle of throe sum gives the quantity per cent., tin 4 form in 
whioh the results of quantitative analyses are usually stated. Occa- 
sionally a constituent o\' a snhstnnec admits o\' being isolated and 

weighed in bhe uncombined state. Thus the amount oi' tneroury in 
a suhstanee ma\ he determined hv separating and weighing bhe 
meroury in bhe metallic condition-, if ooourring as calomel (HgCl) 
or corrosive sublimate (HgCl 8 ), the proportion of ohlorine may then 
be asoertained by oaloulation (Hg 200 3 CI 35.5), 

Nature of Gravimetric Quantitative Analysis. — As above stated, a 
body may be isolated and weighed and its quantity thus asoertained, 
or it may be separated and weighed in combination with another 
body whose oombining proportion is well known-, this is quantita- 
in.- analysis by tin* gravimetric method, 

Nature of Volumetric Quantitative Analysis, Volumetric opera- 
tions depend For success on some accurate initial gravimetric opera* 
tion. A weighed amount of a pure salt is dissolved in a given volume 
of water or other fluid, and thus forms a standard solution. Aoou* 
ratidv measured quantities o( such a solution will obviously oontain 



ATMOSPHERIC PRESSURE, >93 

just as definite amounts of the dissolved salt as if those amounts 
were actually weighed in a balance: and as measuring oooupies less 
time than weighing, the volumetric operations oan be oonduoted 
wnii greal eoonomj of time as compared with the corresponding 
gravimetric operations. Quantitative analysis l»\ the volumetric 
method consists in noting the volume of the standard liquor required 
to be added to the substanoe under examination before a given effeot 
is produoed. Tims, for instanoe, a solution »>f silver nitrate of 
known strength may be used in experimentally ascertaining an un- 
known amount of a chloride in any substance, The silver solution 
is added to a solution of adefinite quantity of the substanoe until 
Hooks of silver chloride oease to be preoipitated i ever^i L08 parts of 
Bilver. added (or 170 of silver nitrates A L08, N s M.o, is, 
total 170) indicates the presence of 35. 5 of ohlorine or an equivalent 
quantity of any chloride The preparation of a standard solution, 
such as that of the silver nitrate to which allusion is hero made, 
requires much care; but onoe it is prepared, oertain analyses can, as 
already indicated, be executed with far more rapidity and ease than 

hy "lay imetrio processes. 

Quantitative Determination <>j {>>) Atmospheric Pressure^ {/>) Tern 

/x nt/iiit, (tiiil (<) Weight. The analysis of solids and liquids often 

involves quantitative determinations not onlv of weight, as jusl indi 
oated, but of temperature and atmospheric pressure. The two lid. 
ber processes will now be explained, after which an outline of vol 
umetrio and gravimetric quantitative analysis will be given. The 

scope of this work precludes any attempt tO describe all Hie little 

mechanioal details observed hy quantitative analysts; essential 
operations, however, are so fully treated that expert manipulators 

will meet, with little dillieully. 



QUANTITATIVE DETERMINATION OF ATMOSPHERIC 
PRESSURE. 

Tin /uinnih /,r. — The analysis of gOS6S and yapors iu\ol\es deter 
ininations of the varying pressure of the atmosphere a.s indicated 

l>\ the barometer (from fldpo?, /><ir<'*, woight, and fiirpov, metron, mea 

sure). 

The ordinary mercurial barometer is a glass tube thirty three or 

thirty four inches long, closed alone end, tilled with mercury, ;iud 

inverted in a small oistern or oup of mercur\ (Fig. 63). The mer 

eury remains in the tuhe, owiii;-, In the \ycivhl or pressure of the 

atmosphere <>n the exposed surface of the liquid, the average height 

of the column being nearly thirty inches. In the popular form of 

the instrument, the wheel barometer, the oistern is formed hy a. 

reOUrvature Of the tuhe (Fig, hi); on the exposed surface of the 
mercury ;i. Iloal is placed, from which a Ihre.id passes oyer a pulley 

and V6S an index yvheneyer tin 1 column of mercury rises or hills. 

As supplied to (he public, these harnmelers are usually enclosed in 

ornamental frames with thermometers attached, [n fcne wheel ha 

rometer the glaSS tuhe and contained column of mercury are alio 



594 



QUANTITATIVE ANALYSIS. 



is 



gether enclosed, the index alone being visible. In the other vari- 
ety the upper end of the glass tube and mercurial column are 
exposed, and the height of the mercury 
Fig. 63. i s ascertained by direct observation. -Fig. 64. 

The aneroid barometer (from a, a, with- 
out, and vqpbz, neros, fluid) consists of a 
small shallow vacuous metal drum, the 
sides of which approach each other when 
an increase of atmospheric pressure oc- 
curs, their elasticity enabling them to 
recede toward their former position on a 
decrease of pressure. This motion is so 
multiplied and altered in direction by 
levers, etc. as to act on a hand travers- 
ing a plate on which are marked num- 
bers corresponding with those showing 
the height of the mercurial column of 
the ordinary barometer by which the 
aneroid was adjusted. The Bourdon ba- 
rometer (from the name of the inventor) 
is a modified aneroid, containing in the 
place of the round metal box a flattened 
vacuous tube of metal bent nearly to a 
circle. These barometers are also useful 
for measuring the pressure in steam-boil- 
ers, etc. Under the name of pressure- 
gauges they are sold to indicate pressure 
of five hundred pounds per square inch and 
Barometer. upward> From their portability (they can Barometer. 

be made of one to two inches in diameter and less than an inch thick) 
they are handy companions for travellers wishing to know the 
heights of hills, mountains, and other elevations. 

(For further information concerning the influence of pressure on 
the volume of a gas or vapor see p. 619 5 and for descriptions of the 
methods of analyzing gases refer to Ganot's "Physics" (translated 
by Atkinson), Miller's " Chemical Physics," and " Analysis of 
Gases" in Watts's u Dictionary of Chemistry.") 




QUANTITATIVE DETERMINATION OF TEMPERATURE. 

General Principles.— As a rule, all bodies expand on the addition, 
and contract on the abstraction, of heat, the alteration in volume 
being constant and regular for equal increments or decrements of 
temperature. The extent of this alteration in a given substance, 
expressed in parts or degrees, constitutes the usual method of intel- 
ligibly stating with accuracy, precision, and minuteness a particular 
condition of warmth or temperature ; that is, of sensible heat. The 
substance commonly employed for this purpose is mercury, the 
chief advantages of which are that it will bear a high temperature 
without boiling, a low temperature without freezing, does not ad- 



TEMPERATURE. 595 

here to glass to a sufficient extent to " wet" the sides of any tube in 
which it may be enclosed, and, from its good conducting power for 
heat, responds rapidly to changes of temperature. Platinum, earthen- 
ware, alcohol, and air are also occasionally used for thermometric 
purposes. 

The Thermometer. — The construction of an accurate ther- 
mometer is a matter of great difficulty, but the following are 
the leading steps in the operation : Select a piece of glass 
tubing having a fine capillary (capillus, a hair) bore and about 
a foot long ; heat one extremity in the blowpipe flame until the 
orifice closes and the glass is sufficiently soft to admit of a bulb 
being blown ; heat the bulb to expel air, immediately plunging 
the open extremity of the tube into mercury ; the bulb having 
cooled, and some mercury having entered and taken the place 
of expelled air, again heat the bulb and tube until the mercury 
boils and its vapor escapes through the bore of the tube ; again 
plunge the extremity under mercury, which will probably now 
completely fill the bulb and tube. When cold the bulb is 
placed in melting ice. The top of the column of mercury in 
the capillary tube should then be within an inch or two of the 
bulb ; if higher, some of the mercury must be expelled by 
heat ; if lower, more metal must be introduced as before. The 
tube is now heated near the open end and a portion drawn out 
until the diameter is reduced to about one-tenth. The bulb is 
next warmed until the mercurial column rises above the con- 
stricted part of the tube, which is then rapidly fused in the 
blowpipe flame and the extremity of the tube removed. 

The instrument is now ready for graduation. The bulb is 
placed in the steam just above some rapidly-boiling water (a 
medium having, ceteris paribus, an invariable temperature), 
and when the position of the top of the mercurial column is 
constant (the flask containing the water and steam being jack- 
eted to prevent loss of heat by radiation), a mark is made on 
the stem by a scratching diamond or a file. This operation is 
repeated with melting ice (also a medium having an invariable 
temperature). The space between these two marks is divided 
into a certain number of intervals termed degrees. Unfor- 
tunately, this number is not uniform in all countries : in Eng- 
land it is 180, as proposed by Fahrenheit ; in France 100, as 
proposed by Celsius (the Centigrade scale), a number generally 
adopted by scientific men ; in some parts of the Continent the 
divisions are 80 for the same interval, as suggested by Reau- 
mur. Whichever be the number selected, similar markings 
should be continued beyond the boiling- and freezing-points as 
far as the length of the stem admits. They may be made on 



596 



QUANTITATIVE ANALYSIS. 



Fig 65. 



Thermometry Scales. 



32- 



the stem itself or on any wood, metal, or earthenware frame on 
which the stem is mounted. 

Thermometric Scales. (Fig. 65). — On the Centigrade (C.) and 
Reaumur (R.). scales the freezing-point 
of water is made zero, and the boiling- 
point 100 and 80 respectively -, on the 
Fahrenheit (F.) scale the zero is placed 
32 degrees below the congealing-point of 
water, the boiling-point of which becomes, 
consequently, 212. Even on the Fahren- 
heit system temperatures below the freez- 
ing-point of water are often spoken of as 
"degrees of frost;" thus 19° as marked 
on the thermometer would be regarded as 
"13 degrees of frost." It is to be re- 
gretted that the freezing-point of water 
is not universally regarded as the zero- 
point, and that the number of intervals 
between that and the boiling-point is not 
everywhere the same. 

The degrees of one scale are easily con- 
verted into those of another if their rela- 
tions be remembered — namely, 180 (F.), 
100 (C), 80 (R.); or 18, 10, and 8; or, 
best, 9, 5, and 4. 



100- 



80 



fjl |§) |P 



Fahren- 
heit. 



Centi- 
grade. 



Reau- 
mur. 



Formula} for the Conversion of Degrees of one Thermometric Scale 

into those of Another. 

F. = Fahrenheit. C. = Centigrade. 

R. = Reaumur. D. = The observed degree. 

If above the freezing-point of water (32° F. ; 0° C. : 0° R.) : 

F. into C. . .' (D - 32) -r- 9 X 5. 

F. " R (D-32)-r-9X 4. 

0. " F D-^ 5 X 9 + 32. 

R. " F D -r- 4 X 9 + 32. 

If below freezing, but above 0° F. (- 17.77° C. ; - 14.22° R.) : 

F. into C - (32 - D) -4- 9 X 5. 

F. " R - (32 - D) -r- 9 X 4. 

C. " F 32- (D-f-5x 9). 

R. " F 32-(D-r-4..X 9). ■ 

If below 0° F. (- 17.77° C. ; - 14.22° R.) : 

F. into C - (D + 32) -4- 9 X 5. 

F. " R 



- (D + 32) -r- 9 X 4. 



F -(D-f- 5x9) 

- (D -r- 4 X 9) 



F. 



32. 
32. 



For all degrees 
C. into R. 
R. " C. 



D-f5x4. 
D-I-4X5. 



. 



TEMPERATURE. 



597 



Iii ascertaining the temperature of a liquid the bulb of a 
thermometer is simply inserted and the degree noted! In 
determining the boiling-point also the bulb is inserted in the 
liquid if a pure substance. In taking the boiling-point of a 
substance which is being distilled from a mixture, the bulb of 
the thermometer should be in the vapor, but not beneath nor 
very near to the surface of the boiling liquid. 

The " boiling-point " of a liquid is the temperature at which 
the elasticity of the vapor of the substance overcomes the 
atmospheric or other pressure to which the liquid is exposed. 
If the pressure is equal to 760 mm. (29.92 inches) of mercury, 
water will boil at 100° C. (212° F.). The boiling-point of a 
drop of a fluid is taken by introducing it into the closed extrem- 
ity of a small U tube, the remaining portion of the closed limb 
being filled with mercury. The tube is lowered into a bath, the 
open limb being above the surface of the fluid of the bath. The 
bath is slowly and equally heated, and the boiling-point of the 
liquid, indicated by the mercury falling until it is level in the two 
limbs, taken by a thermometer whose bulb is close to the U tube. 

The following are the boiling-points of a few substances met 
with in pharmacy : 



Alcohol, absolute 

" 84 per cent 

" 49 per cent, (proof spirit) .... 

" amylic 

Benzol 

Bromine . (below) 

Benzoic acid 

Carbolic acid 

Chloroform 

Ether (B. P.) (below) 

" pure 

Mercury, in vacuo (as in a thermometer) . 

" • in air (barometer at 30 inches) . 

Water (barometer at 29.92 inches) .... 

" ( " at 29.33 " )...... 

" ( " at 28.74 " )■.-... 

Saturated solutions of — 

Cream of tartar . , . 

Common salt 

Sal-ammoniac 

Sodium nitrate 

Sodium acetate 

Calcium chloride 

__ __ 



Centigrade. Fahrenheit. 



78.3 


173 


79.5 


175 


81.4 


178.5 


132.2 


270 


80.6 


177 


63 


145.4 


239.0 


462 


187.8 


370 


61 


142 


40.5 


105 


35 


95 


304 


580 


350 


662 


100 


212 


99.5 


211 


99 


210 


101 


214 


106.6 


224 


113.3 


236 


119 


246 


124.4 


256 


179.4 


355 



598 



QUANTITATIVE ANALYSIS. 



To Determine Melting-points of Fats. — To melt at a given 
temperature is a constant property of a substance ; therefore, 
a melting-point, once it is accurately determined, becomes a 
valuable indicator of purity in a substance. Heat a fragment 
of the substance (spermaceti or wax, for example) till it lique- 
fies, and then draw up a small portion into a thin glass tube 
about the size of a knitting-needle. Immerse the tube in cold 
water contained in a beaker, and slowly heat the vessel till the 
thin opaque cylinder of solid fat melts and becomes transpar- 
ent : a delicate thermometer placed in the water indicates the 
point of change to the fifth of a degree. Remove the source 
of heat and note the congealing-point of the substance ; it will, 
in nearly all cases, be identical with or close to the melting- 
point. 

The following are melting-points of substances official in the 
British Pharmacopoeia : 



Acetic acid, glacial 

" " " congeals at ..... 

Benzoic acid 

Carbolic acid 

Oil of theobroma (about) 

Phosphorus 

Prepared lard (about) 

" suet 

Spermaceti 

"White wax 

Yellow wax 



In degrees In degrees 
Centigrade. Fahrenheit. 



8.9 


48 


1.1 


34 


120 


248 


35 


95 


32 


90 


" 43.3 


110 


38 


100 


39.5 


103 


44 to 50 


111 to 122 


63.3 


146 


63.3 


146 



Pyrometers. — Temperatures above the boiling-point of mer- 
cury are determined by ascertaining to what extent a bar of 
platinum or porcelain has elongated. The bar is enclosed in a 
cavity of a suitable case, a plug of platinum or porcelain placed 
at one end of the bar, and the whole exposed in the region the 
temperature of which is to be found. After cooling, the dis- 
tance to which the bar has forced the plug along the cavity is 
accurately measured and the corresponding degree of temper- 
ature noted. The value of the distance is fixed for low tem- 
peratures by comparison with a mercurial thermometer, and 
the scale carried upward through intervals of equivalent length. 
Such thermometers are conventionally distinguished from or- 



TEMPERATURE. 



599 



dihary instruments by the name pyrometer (from nop, pur, fire, 
and fiirpov, metron, measure). 

The order of fusibility of a few of the metals is as follows : 



Mercury 
Potassium 
Sodium 
Tin . . 
Bismuth 
Lead . . 
Zinc . . 
Antimony 
Silver . 
Copper . 
Gold r . 
Cast iron 



In degrees 
Centigrade. 



- 39.4 
+ 62.5 
97.6 
227.8 
264 
325 
411.6 
621 
1023 
1091 
1102 
1530 



In degrees 
Fahrenheit. 



- 39 
+ 144.5 

207.7 

442 

507 

617 

773 

1150 

1873 

1996 

2016 

2786 



QUESTIONS AND EXERCISES. 

On what fundamental laws are the operations of quantitative analysis 
hased ? — What is the general nature of gravimetric quantitative analysis ? 
—Describe the general principle of volumetric quantitative analysis. — 
How are variations in atmospheric pressure determined ? — Explain the 
construction and mode of action of barometers. — In what respect does 
a wheel-barometer differ from an instrument in which the readings are 
taken from the top of the column of mercury? — Describe the principles 
of action of an aneroid barometer. — On what general principles are 
thermometers constructed? — What material is employed in making 
thermometers ? — Why is mercury selected as a thermometric indicator ? 
— Describe the manufacture of a mercurial thermometer. — How are 
thermometers graduated ?— Give formulae for the conversion of the 
degrees of one thermometric scale into those of another, (a) when the 
temperature is above the freezing-point of water; (6) below 32° F., but 
above 0° F., and (c) below 0° F. — Name the degree C. equivalent to 
60° F — What degree C. is represented by — 4° F. ?— Mention the degree 
F. indicated by 20° C — Convert 100° E. into degrees C. and F.— State the 
boiling-points of alcohol, chloroform, ether, mercury, and water on 
either thermometric scale. — Describe the details of manipulation in 
estimating the melting-points of fats. — In what respect do pyrometers 
differ from thermometers ? — Mention the melting-points of glacial acetic 
acid, oil of theobroma, lard, suet, and wax. — Give the fusing-points of 
tin, lead, zinc, copper, and cast iron. 



600 QUANTITATIVE ANALYSIS. 



QUANTITATIVE DETERMINATION OF WEIGHT. 

All bodies, celestial and terrestrial, attract each other, the amount 
of attraction being in direct proportion to the quantity of matter 
of which they consist, and in inverse proportion to the squares of 
their distances. This is gravitation. When gravitation in certain 
directions is exactly counterbalanced by gravitation in opposite 
directions, a body (e. g. the earth) remains suspended in space. 
Such a body, in relation to other bodies, has gravity, but not 
weight. Weight is the effect of gravity, being the excess of grav- 
itation in one direction over and above that exerted in the opposite 
direction. Weight, truly, in any terrestrial substance, is the excess 
of attraction which it and the earth have for each other over and 
above the attraction of each in opposite directions by the various 
heavenly bodies. But, practically, the weight of any terrestrial 
substance is the effect of the attraction of the earth only. Specific 
weight is the definite or precise weight of a body in relation to its 
bulk ; it is more usually, but not quite correctly, termed specific 
gravity — gravity belonging to the earth, and not, in any sensible 
degree, to the substance.* 



QUESTIONS AND EXEECISES. 

What is understood by gravitation? — State the difference between 
weight and gravity. — Mention a case in which a body has gravity, but 
no apparent weight. — Practically, what causes the weight of terrestrial 
substances ? 



Weights and Measures. 



The Balance. — The balance used in the quantitative operations 
of analytical chemistry must be accurate and sensitive. The points 
of suspension of the beam and pan should be polished steel or agate 
knife-edges working on agate planes. It should turn easily and 
quickly, without too much oscillation, to -^q or ^^ of a grain, or 
^ of a milligramme, when 1000 grains, or 50 or 60 grms., are 
placed in each pan. (Grammes are weights of the metric system, 
a description of which is given on the next two or three pages.) 
The beam should be light out strong, capable of supporting a load 
of 1500 grains or 100 grammes : its oscillations are observed by the 
help of a long index attached to its centre, and continued down- 
ward for some distance in front of the supporting pillar of the 
balance. The instrument should be provided with screws for pur- 
poses of adjustment, a mechanical contrivance for supporting the 

* It must be remembered, also, that centrifugal influence and gravita- 
tion are antagonistic. 



WEIGHTS AND MEASURES. 601 

beam above its bearings when not in use or during the removal or 
addition of weights, spirit-levels to enable the operator to give it a 
horizontal position, and be enclosed in a glass case to protect it 
from dust. It should be placed in a room the atmosphere of which 
is not liable to be contaminated by acid fumes, in a situation as 
free as possible from vibration ; and a vessel containing lumps of 
quicklime should be placed in the case to keep the enclosed air dry 
and prevent the formation of rust on any steel knife-edges or other 
parts. During weighing the doors of the balance-case should be 
shut, in order that currents of air may not unequally influence the 
pans. 

The Weights. — These should be preserved in a box having a sep- 
arate compartment for each. They must not be lifted directly with 
the fingers, but by a small pair of forceps. If grain weights, they 
should range from 1000 gr. to ^ gr., a ^ weight being fashioned 
of gold wire to act as a "rider" on the divided beam, and thus 
indicate by its position lOOths and lOOOths of a grain. From -^ to 
10 grs. the weights may be of platinum or aluminium ; thence 
upward to 1000 grains of brass. The relation of the weights to each 
other should be decimal. Metric decimal weights may range from 
100 grammes to 1 gramme, of brass, and thence downward to 1 
centigramme, of platinum or aluminium, a gold centigramme rider 
being employed to indicate milligrammes and tenths of a milli- 
gramme. 

" The weights and measures referred to by physicians in prescrib- 
ing, and used by pharmacists in dispensing, medicines are, in the 
United States, either those of the ' apothecaries ' or Troy system of 
weights and the wine measure, or those of the metric system." 

Troy Weights. — These are derived from the Troy pound, and are 
exhibited in the following table, with their signs annexed : 



One pound, 


ft> = 


12 ounces = 5760 grains. 


One ounce, 


n = 


8 drachms = 480 grains. 


One drachm, 


z = 


3 scruples = 60 grains. 


One scruple, 


d ■ 


= 20 grains. 


One grain, 


gr. . 


= 1 grain. 



It is highly important that persons engaged in preparing medi- 
cines should be provided with Troy weights. But those who are 
not so provided can make their avoirdupois weights available as 
substitutes for Troy weights by bearing in mind that 42.5 grains, 
added to the avoirdupois ounce, will make it equal to the Troy 
ounce, and that 1240 grains, deducted from the avoirdupois pound, 
will reduce it to the Troy pound. 

Measures. — These are derived from the wine gallon, and are given 
in the following table, with their signs annexed : 

One gallon, C = 8 pints = 61,440 minims. 

One pint, O = 16 fluidounces = 7,680 minims. 

One nuidounce, f !| = 8 fluidrachms = 480 minims. 

One fluidrachm, f3 = 60 minims. 

One minim, Tr\, = 1 minim. 



602 QUANTITATIVE ANALYSIS. 



Relation of Troy Weight and Wine Measure. 



1 minim = 0.95 grains. 
1 f£ = 56.96 ^ " 
1 f£ =455.69 " . 



1 grain = 1.05 minims. 
1 3 = 63.2 " 
1 S = 505.6 " 



Weights and Measures of the United States Pharmacopoeia. 

" Weight and volume are expressed in the units of the interna- 
tional system based on the metre. In cases where only relative 
quantities are stated, the proportions are expressed in parts by 
weight or by volume. All weights and measures used now (1893) 
are derived from the United States national prototype standards of 
the metre and the kilogramme. The actual litre is the volume of 
one kilogramme of pure water at the temperature of its maximum 
density in vacuo. Theoretically, the litre is equal to one cubic 
decimetre or 1000 cubic centimetres. The United States yard is 
defined to be equal to f ffy§§ metre ; the commercial pound (avoir- 
dupois) is defined as being equal to ■££££■£££££■§ kilogramme ; and 
the liquid gallon is the volume of 3785.434 grammes (58418.1444 
grains) of water at the temperature of its maximum density, weighed 
in vacuo. 1 '' 

The Metric System of Weights (the word metric is from the 
Greek /uerpov, metron, measure) is greatly to be preferred to the 
British, the relation of the metric weights of all denominations to 
measures of length, capacity, and surface being so simple as to be 
within the perfect comprehension of a child ; while under the Brit- 
ish plan the weights have no such relation either with each other 
or with the various measures. Moreover, the metric system is in 
perfect harmony with the universal method of counting ; it is a 
decimal system. 

[It is perhaps impossible to realize, much more express, the ad- 
vantages we enjoy from the fact that in every country of the world 
the system of numeration is identical. That system is the decimal. 
Whatever language a man speaks, his method of numbering is deci- 
mal ; his talk concerning numbers is decimal ; his written or printed 
signs signifying number are decimal. With the figures 1, 2, 3, 4, 
5, 6, 7, 8, 9, he represents all possible variations in number, the 
position of a figure in reference to its companions alone determining 
its value, a figure on the left hand of any other figure in an alloca- 
tion of numeral symbols (for example, 1894) having ten times the 
value of that figure, while the figure on the right hand of any other 
has a tenth of the value of that other. When the youngest pupil is 
asked how many units there are in 1894, he smiles at the simplicity 
of the question, and says, 1894. How many tens? 189 and 4 over. 
How many hundreds? 18 and 94 over. How many thousands? 
1 and 894 over. But if he is asked how many scruples there are in 
1894 grains, how many drachms, how many ounces, he brings out 
his slate and pencil. And so with the pints or gallons in 1894 
fluidounces, or the feet and yards in 1894 inches, or the pence, shil- 



WEIGHTS AND MEASURES. 



603 



lings, and pounds in 1894 farthings ; to say nothing of cross-ques- 
tions, such as the value of 1894 articles at 9s. 6d. per dozen, or of 
the perplexity caused by the varying values of several individual 
weights or of measures of length, capacity, and surface in different 
parts of the country. What is desired is, that there should be an 
equally simple decimal relation among weights and measures and 
coins as already universally exists among numbers. This condition 
of things having already been introduced into most other countries, 
there is no good reason why it should not, in due time, be accom- 
plished in the United States and Great Britain. The difficulty in 
the way consists in requiring, more or less suddenly, every one of 
the many millions of persons in the country to relinquish the life- 
long use of words expressive of the hourly wants of life — such words 
as pounds, pints, pence, etc., for words such as kilos, litres, cents, 
etc., which will not express those wants until after weeks or months, 
or perhaps years. The difficulty is one that explanation cannot 
meet, for it is one of association which time alone can resolve, at all 
events for the great mass of people. Still, "what man has done 
man can do."] 

The system of weights and measures legalized in Great Britain 
by "the Metric Weights and Measures Act, 1864," is founded on 
the metre. Fig. 66 represents a pocket folding-measure the tenth 
part of a metre in length, divided into 10 centimetres, and each 
centimetre into 10 millimetres. 

Fig. m. 



Ill III IN 


imtini 


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7 


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10 



The Decimetre. 



The units of the system, with their multiples and submultiples, 
are as follows : 

Length. — The Unit of Length is the Metre, derived from the 
measurement of the quadrant of a meridian of the earth. (Prac- 
tically, it is the length of certain carefully-preserved bars of metal, 
from which copies have been taken.) 

Surface. — The Unit of Surface is the Are, which is the square 
of ten metres. 

Capacity. — The Unit of Capacity is the Litre, which is the cube 
of a tenth part of a metre. 

Weight. — The Unit of Weight is the Gramme, which is the weight 
of that quantity of distilled water, at its maximum density, which 
fills a cube of the one-hundredth part of the metre. 



604 



QUANTITATIVE ANALYSIS. 



Table. 

Note. — Multiples are denoted lby the Greek words u Deka," ten, 
" Hecto," hundred, " Kilo," thousand. 
Subdivisions by the Latin words, " Deci," one-tenth, 
" Centi," one-hundredth, " Milli," one-thousandth. 



Quantities. 


Length. 


Surface. 


Capacity. 


Weight. 


1000 


Kilo-metre 


. 


Kilo-litre 


Kilo-gramme. 


100 


Hecto-metre 


Hectare 


Hecto-litre 


Hecto-gramme 


10 


Deca-metre 




Deca-litre 


Deca-gramme. 


1 (Units) 


METRE 


ABE 


LITRE 


GRAMME. 


.1 


Deca-metre 




Deci-litre 


Deci-gramme. 


.01 


Centi-metre 


Centiare 


Centi-litre 


Centi-gramme. 


.001 


Milli-metre 




Milli-litre 


Milligramme. 



When the metric method is exclusively adopted, these units and 
table, comprising the entire system of weights and measures, repre- 
sent all that will be essential to be learnt in lieu of the numerous 
and complicated tables hitherto in use. Adopting the style of ele- 
mentary books on arithmetic, the table may be expanded thus : 

10 Milligrammes make 1 Centigramme. 

10 Centigrammes " 1 Decigramme. 

10 Decigrammes " 1 Gramme. 

10 Grammes " 1 Decagramme. 

10 Decagrammes " 1 Hectogramme. 

10 Hectogrammes " 1 Kilogramme. 

10 Millilitres make 1 Centilitre, 

etc. 

10 Millimetres make 1 Centimetre, 

etc. 

Abbreviations. — Metre = m ; decimetre = dm ; centimetre = cm ; 
millimetre = mm ; kilometre = km. Square metre = m? ; cubic 
metre = m 3 ; and so on. Litre = 1; decilitre = dl ; etc. Kilo- 
gramme — kg; decagramme = dkg; gramme = ^ ; decigramme = 
dg ; centigramme = eg ; and milligramme = mg. 

The following approximate British equivalents of metrical units 
should be committed to memory : 

1 Metre = 3 feet 3 inches and 3 eighths. 
1 Are = a square whose side is 11 yards. 

1 Litre = If pints. 
1 Gramme = 15 J grains. 
The Kilometre is equal to 1100 yards. 
The Hectare = 2£ acres nearly. 
The Metric Ton of 1000 Kilogrammes = 19 cwt. 2 qrs. 20 lbs. 10 oz. 
The Kilogramme = 2 lbs. 3£ oz. nearly. 

(For exact equivalents, in many forms, see pp. 606 and 607.) A 
litre of water at 39° F. weighs 15,432 grains ; at 50° F., 15,429 
grains ; at 60° F. it weighs 15,418 grains ; at 70° F., 15,403 grains ; 
and at 80° F., 15,383 grains (Pile). (The word gramme is sometimes, 



WEIGHTS AND MEASURES. 605 

unfortunately, written gram, which too closely resembles the word 
grain.) 

Decimal Coinage. — In most countries where the metric system of 
weights and measures is employed a decimal division of coins is 
also adopted. This course, conjoined with the ordinary decimal 
method of enumerating, which, fortunately, is in universal use, 
renders calculations of all kinds most simple — easy to an extent 
which cannot be conceived in countries like England where the 
operations of weighing, measuring, paying, and counting have only 
the most absurdly intricate relations to each other. 



The General Council under whose authority the British Pharma- 
copoeia is issued encourages medical practitioners and pharmacists 
in the adoption of the metric system, and gives the annexed state- 
ment of metric weights and measures : 



WEIGHTS AND MEASURES OF THE METRICAL 

SYSTEM. 



1 Milligramme =the thousandth part of one grm., or 0.001 grin. 
1 Centigramme = the hundredth " 0.01 " 

1 Decigramme = the tenth " 0.1 " 

1 Gramme = weight of a cubic centimetre of 

water at 4° C. 1.0 

1 Decagramme = ten grammes 10.0 " 

1 Hectogramme = one hundred grammes 100.0 " 

1 Kilogramme = one thousand grammes 1000.0 (1 kilo). 



MEASURES OF CAPACITY. 

1 Millilitre = 1 cubic centim., or the mea. of 1 gramme of water. 
1 Centilitre = 10 " " 10 " 

1 Decilitre = 100 " " 100 



a u 



1 Litre -1000 " " 1000 " (1 kilo.) 



MEASURES OF LENGTH. 



1 Millimetre = the thousandth part of one metre, or 0.001 metre. 
1 Centimetre = the hundredth " " 0.01 " 

1 Decimetre = the tenth " " 0.1 ^ 

1 Metre = the ten-millionth part of a quarter of the meridian 

of the earth. 



606 



QUANTITATIVE ANALYSIS. 



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607 



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608 



QUANTITATIVE ANALYSIS. 



WEIGHTS AND MEASURES OF THE BRITISH 
PHARMACOPCEIA OF 1885. 



1 Grain gr. 
1 Ounce oz. 
1 Pound ft). 



WEIGHTS. 



= 16 ounces 



= 437.5 grains. 
= 7000.0 " 



MEASURES OF CAPACITY. 



1 Minim 
1 Fluidrachm 
1 Fluidounce 
1 Pint 
1 Gallon 



min. 
fl. drm. 
fl. oz. 
O. 

c. 



= 60 minims. 
= 8 fluidrachms. 
= 20 fluidounces. 
= 8 pints. 



MEASURES OP LENGTH. 

1 inch = 
12 inches = 1 foot. 
36 " = 3 feet = 1 yard. 
(1 cubic inch of distilled water at 62° F. and 30 inch barom. 
= 252.458 grains.) 

RELATION OP MEASURES TO WEIGHTS. 

1 Minim is the measure of 0.9114583 grain of water. 

1 Fluidrachm " 54.6875 grains " 

1 Fluidounce " 1 ounce or 437.5 " " 

1 Pint " 1.25 pound, or 8750.0 " " 

1 Gallon " 10 pounds, or 70,000.0 " 

(Gtt. =guttce, drops. The term "drop" indicates a quantity 
which is indefinite, and should only be used when approximative- 
ness is alone desired.) 

The preceding (De La Rue's) tables, pp. 606, 607, will be found 

useful. 



WEIGHTS AND MEASURES OF THE U. S. 
PHARMACOPOEIA. 

The following tables, from the United States Pharmacopoeia of 
1880, especially taken together with those of the Pharmacospia of 
1890, will be found extremely useful : 

A.— MEASURES OF LENGTH. 

I. Relation of Metric to the United States Measures of 
Length. 



1 Metre 
1 Decimetre 
1 Centimetre 
1 Millimetre 



39.370432 inches. 
3.937043 " 
0.393704 " 
0.039370 " 



WEIGHTS AND MEASURES. 



609 



II. Relation of United States to Metric Measures of Length. 

1 Yard (or 36 Inches) = 0.91439 Metre. 

1 Foot (or 12 Inches) = 30.40 Centimetres. 



fuches. 




Centimetres. 


Inches. 




Centimetres. 


Inch. 




Centimetre. 


11 


= 


27.9 


5 


= 


12.7 


1 


= 


12.5 


10 


= 


25.4 


4 


= 


10.2 


l 
4 


— 


6.25 


9 


= 


22.9 


3 


= 


7.6 


1 
"8 


— 


3.12 


8 


= 


20.3 


2 


= 


5.1 


1 
T6 


- — 


1.54 


7 


= 


17.8 


1 


= 


2.5 


A 


— 


1.00 


6 


= 


15.2 















B.— MEASUEES OF CAPACITY. 
III. Relation of Metric to United States Fluid Measures. 



ubic Centim. Fluidounces. 


Cubic Centim. Fluidrachms. 


Cubic Centim. 


Minima 


1 ? 000 


= 33.81 


15 


= 


4.06 


0.40 


— 


6.49 


950 


= 32.12 


10 


= 


2.71 


0.35 


— 


5.68 


900 


= 30.43 


9 


== 


2.43 


0.30 


— 


4.87 


850 


= 28.74 


8 


= 


2.16 


0.25 


— 


4.06 


800 


= 27.05 


7 


= 


1.89 


0.20 


= 


3.25 


750 


= 25.36 


6 


= 


1.62 


0.19 


— 


3.08 


700 


= 23.67 


5 


= 


1.35 


0.18 


= 


2.92 


650 


.= 21.98 


4 


= 


1.08 


0.17 


= 


2.76 


600 


= 20.29 








0.16 


— 


2.60 


550 


= 18.59 


Cubic Centim. 


RJinims. 


0.15 


= 


2.43 


500 


= 16.90 


3 


= 


48.69 


0.14 


= 


2.27 


450 


= 15.22 


2 


— 


32.46 


0.13 


zz= 


2.11 


400 


= 13.53 


1 


= 


16.23 


0.12 


= 


1.95 


350 


= 11.84 


0.95 


— 


15.42 


0.11 


zzz: 


1.79 


300 


= 10.14 


0.90 


= 


14.61 


0.10 


= 


1.62 


250 


= 8.45 


0.85 


— 


13.80 


0.09 


—■ 


1.46 


200 


= 6.76 


0.80 


= 


12.98 


0.08 


z= 


1.30 


150 


= 5.07 


0.75 


^zz 


12.17 


0.07 


-zzr 


1.14 


100 


== 3.38 


0.70 


= 


11.36 


0.06 


— 


0.97 


30 


= . 1.01 


0.65 


— 


10.55 


0.05 


=z 


0.81 






0.60 


zz= 


9.74 


0.04 


= 


0.65 


ubic Centim. Fluidrachms. 


0.55 


— 


8.93 


0.03 


== 


0.49 


25 


6.76 


0.50 


— 


8.12 


0.02 


= 


0.32 


20 


= 5.41 


0.45 


= 


7.30 


0.01 


= 


0.16 


IV. Relation of U 


nited States 


to Metr 


ic Fluid 


Measures. 


Linims. 


Cubic Centim. 


Minims. 


Cubic Centim. 


Minims. 


Cubic Centim 


1 


= 0.06 


8 


= 


0.49 


15 


= 


0.92 


2 


= 0.12 


9 


= 


0.55 


16 


= 


0.99 


3 


= 0.18 


10 


= 


0.62 


17 


= 


1.05 


4 


= 0.25 


11 


= 


0.68 


18 


= 


i.h 


5 


= 0.31 


12 


= 


0.74 


19 


= 


1.17 


6 


= 0.37 


13 


rzr 


0.80 


20 


= 


1.23 


7 


= 0.43 


14 


= 


0.86 


21 


= 


1.29 



610 



QUANTITATIVE ANALYSIS. 



Relation of United States to Metric Fluid Measures. — Coni. 



Mintms. 


Cubic Centim. 


Fluidrachms. Cubic Centim. 


Fluidounces. 


Cub. Centim. 


22 


=r 


1.36 


3 


— 


11.09 


11 


=: 


325.25 


23 


= 


1.42 


4 


— 


14.79 


12 


= 


354.82 


24 


— 


1.48 


5 


— 


18.48 


13 


= 


384.40 


25 


= 


1.54 


6 


= 


22.18 


14 


= 


413.97 


26 


= 


1.60 


7 


= 


25.88 


15 


= 


443.54 


27 


== 


1.66 


8 


== 


29.57 


16 


== 


473.11 


28 


— = 


1.73 


9 


= 


33.27 


17 


rzr 


502.69 


29 


— 


1.79 


10 


— 


36.97 


18 


z=_ 


532.26 


30 


= 


1.85 


11 


= 


40.66 


19 


= 


561.93 


35 


=z 


2.16 


12 


=: 


44.36 


20 


z=: 


591.50 


40 


— 


2.46 


13 


— 


48.06 


21 


= 


621.08 


45 


= 


2.77 


14 


= 


51.75 


22 


= 


650.65 


50 


— 


3.08 


15 


= 


55.45 


23 


r=r 


680.22 


55 


— 


3.39 


16 


r^z 


59.10 


24 


= 


709.80 


60 


— 


3.70 








25 


= 


739.37 


70 


= 


4.31 


Fluidounces. 




26 


= 


768.94 


80 


= 


4.93 


3 


•==. 


88.67 


27 


= 


798.51 


90 


= 


5.54 


4 


= 


118.24 


28 


= 


828.09 


100 


= - 


6.16 


5 


=z 


147.81 


29 


— 


857.66 


110 


= 


6.78 


6 


-=. 


177.39 


30 


= 


887.23 


120 


= 


7.39 


7 


— 


206.96 


31 


= 


916.80 








8 


= 


236.53 


32 


=: 


946.38 








9 


= 


266.10 


64 


= 


1892.75 








10 


= 


295.68 


128 


= 


3785.51 



C— WEIGHTS. 

V. Relation of Metric to Apothecaries' or Troy Weight. 



Grammes. 




Grains. 


Grammes. 




Grains. 


Grammes. 




Grains. 


0.0010 


.= 


0.015 


0.0125 


= 


0.193 


0.120 


= 


1.852 


0.0013 


= 


0.019 


0.0150 


= 


0.231 


0.130 


rzr: 


2.006 


0.0015 


= 


0.023 


0.0200 


= 


0.309 


0.140 


= 


2.161 


0.0020 


^zz: 


0.031 


0.0250 


z= 


0.386 


0.150 


r=z 


2.315 


0.0025 


= 


0.039 


0.0300 


= 


0.463 


0.160 


= 


2.469 


0.0030 


:== 


0.046 


0.0350 


= 


0.540 


0.170 " 


•= 


2.623 


0.0035 


= 


0.054 


0.0400 


— 


0.617 


0.180 


— 


2.778 


0.0040 


== 


0.062 


0.0450 


==z 


0.694 


0.190 


=: 


2.932 


0.0045 


— 


0.069 


0.050 


— 


0.772 


0.200 


— 


3.086 


0.0050 


r=r 


0.077 


0.055 


zzz 


0.849 


0.210 


z=z 


3.241 


0.0055 


— 


0.085 


0.060 


— 


0.926 


0.220 


=Z 


3.395 


0.0060 


== 


0.093 


0.065 


=: 


1.003 


0.230 


z=: 


3.549 


0.0065 


— 


0.100 


0.070 


— 


1.080 


0.240 


= 


3.704 


0.0070 


z=z 


0.108 


0.075 


= 


1.157 


0.250 


=: 


3.85S 


0.0075 


— 


0.116 


0.080 


= 


1.235 


0.260 


= 


4.012 


0.0080 


=zr 


0.123 


0.085 


=: 


1.312 


0.270 


— 


4.167 


0.0085 


— ; 


0.131 


0.090 


= 


1.389 


0.280 


=: 


4.321 


0.0090 


r= 


0.139 


0.095 


= 


1.466 


0.290 


= 


4.475 


0.0095 


=z 


0.147 


0.100 


= 


1.543 


0.300 


=: 


4.630 


0.0100 


== 


0.154 


0.110 


= 


1.698 


0.310 


= 


4.784 



WEIGHTS AND MEASURES. 



611 



Relation of Metric to Apothecaries' or Troy Weight. — Cont. 



Grammes. 




Grains. 


Grammes 




Grains. 


Grammes. 


Grains. 


0.320 


— 


4.938 


13 


= 


200.621 


39 


— 


601.862 


0.330 


— 


5.093 


14 


= 


216.053 


40 


— 


617.294 


0.340 


— 


5.247 


15 


— 


231.485 


50 


— 


771.617 


0.350 


— 


5.401 


16 


— 


246.918 


60 


— 


925.941 


0.360 


— 


5.556 


17 


— 


262.350 


70 


— 


1080.264 


0.370 


= 


5.710 


18 


= 


277.782 


80 


— 


1234.588 


0.380 


= 


5.864 


19 


= 


293.215 


90 


— 


1388.911 


0.390 


= 


6.019 


20 


==. 


308.647 


100 


= 


1543.235 


0.400 


— 


6.173 


21 


= 


324.079 


125 


— 


1929.044 


0.500 


= 


7.716 


22 


— 


339.512 


150 


= 


2314.852 


0.600 


=; 


9.259 


23 


— 


354.944 


200 


=; 


3086.470 


0.700 


= 


10.803 


" 24 


= 


370.376 


250 


= 


3858.087 


0.800 


— : 


12.346 


25 


= 


385.809 


300 


— 


4629.705 


0.900 


= 


13.889 


26 


■=. 


401.241 


333 


= 


5144.118 


1 


= 


15.432 


27 


= 


416.673 


350 


==z 


5401.322 


2 


=: 


30.865 


28 


=r 


432.106 


400 


=z 


6172.940 


3 


= 


46.297 


29 


= 


447.538 


450 


= 


6944.557 


4 


= 


61.729 


30 


= 


462.970 


500 


= 


7716.174 


5 


= 


77.162 


31 


= 


478.403 


600 


= 


9259.409 


6 


= 


92.594 


32 


= 


493.835 


700 


= 


10802.644 


7 


= 


108.026 


33 


= 


509.268 


750 


= 


11574.262 


8 


— 


123.459 


34 


— 


524.700 


800 


=: 


12345.879 


9 


=: 


138.891 


35 


== 


540.132 


900 


= 


13889.114 


10 


z= 


154.323 


36 


= 


555.565 


1000 


= 


15432.350 


11 


= 


169.756 


37 


=z 


570.997 








12 


= 


185.188 


38 


= 


586.429 









VI. The Relation of Apothecaries' (or Troy) to Metric Weight. 

Grains. Grammes. 



Grains. 

A 

i 

^0 

1 

1 

^0 
1 

a 

i 

sw 

1 

23- 

1 
24 

I 
20 

1 
T¥ 

1 
T5- 

t\ 

l 
T2" 

■A 



Grammes. 

0.00101 
0.00108 
0.00130 
0.00135 
0.00162 
0.00180 
0.00202 
0.00216 
0.00259 
0.00270 
0.00324 
0.00360 
0.00405 
0.00432 
0.00540 
0.00648 
0.00810 
0.01080 
0.01296 



2 = 

f = 

4 = 

5 = 

6 = 

7 = 

8 = 

9 = 

10 = 

11 = 

12 = 

13 = 



0.01620 
0.02160 
0.03240 
0.04860 
0.06480 
0.09720 
0.12960 
0.16200 
0.19440 
0.25920 
0.32399 
0.38879 
0.45359 
0.51839 
0.58319 
0.64799 
0.71297 
0.77759 
0.84239 



Grains 


. 


Grammes. 


14 


= 


0.90718 


15 


— : 


0.97198 


16 


= 


1.037 


17 


= 


1.102 


18 


= 


1.166 


19 


= 


1.231 


20 


= 


1.296 


21 


= 


1.361 


22 


= 


1.426 


23 


= 


1.458 


24 


==: 


1.555 


25 


=z 


1.620 


26 


=z 


1.685 


27 


= 


1.749 


28 


= 


1.814 


29 


= 


1.869 


30 


= 


1.944 


40 


=; 


2.592 


50 


zz= 


3.240 



612 



QUANTITATIVE ANALYSIS. 



Relation of Apothecaries' (or Troy) to Metric Weight. — Cont. 



Drachms. 


Grammes. 


Ounces. 




Grammes. 


Ounces. 




Grammes. 


( 


— 


3.888 


1* 


r= 


46.655 


11 


— 


342.138 


2 


= 


7.776 


2 


= 


62.207 


12 


= 


373.250 


3 


== 


11.664 


3 


= 


93.310 


13 


zzz: 


404.345 


4 


= 


15.552 


4 


= 


124.414 


14 


— 


435.449 


5 


■= 


19.440 


5 


z=z 


155.517 


15 


— 


466.552 


6 


= 


23.328 


6 


— 


186.621 


16 


;= 


497.656 


7 


= 


27.216 


7 


= 


217.724 


17 


= 


528.759 








8 


= 


248.823 


18 


= 


559.863 


Ounces. 






9 


— 


279.931 


19 


= 


590.966 


1 


= 


31.103 


10 


= 


311.035 


20 


= 


622.070 




VII. 


Kelation 


of Metric 


to Avoirdupois Weight. 




Avoirdupois Ounces 


Avoirdupois Ounces 


Avoirdupois Ounces 




aud Grains. 




aud Grains. 




and Grains. 


Grammes. 


Oz. Grs. 


Grammes. 




Oz. Grs. 


Grammes. 




Oz. Grs. 


28.35 




1 


50 


=: 


1 334 


500 


= 


17 279 


29 


= 


1 10 


60 


= 


2 50* 


550 


— 


19 175 


30 


= 


1 25* 


70 


=z 


2 205 


600 


= 


21 72 


31 


= 


1 41 


80 


= 


2 359 


650 


— 


22 405* 


32 


= 


1 56* 


90 


— 


3 76* 


700 


= 


24 303 


' 33 


= 


1 72 


100 


= 


3 230* 


750 


= 


26 198* 


34 


= 


1 87| 


150 


= 


5 127 


800 


= 


28 96 


35 


= 


1 103 


200 


= 


7 24 


850 


= 


29 429 


36 


= 


1 118 


250 


= 


8 358 


900 


= 


31 326* 


37 


= 


1 133* 


300 


= 


10 255 


950 


== 


33 222 


38 


= 


1 149 


350 


= 


12 151* 


1000 


= 


35 120 


39 


= 


1 164* 


400 


z= 


14 48 








40 


= 


1 180 


450 


— 


15 382 










VIII. 


Relation 


r of Avoirdupois to D 


Metric Weight. 


Avoirdupois 
Ounces. 


Grammes. 


Avoirdupois 
Ounces. 


Grammes. 


Avoirdupois 
Pounds. 


Grammes. 


1 
TG" 


= 


1.772 


7 


== 


198.447 


1 


— 


453.592 


* 


— 


3.544 


8 


= 


226.796 


2 


= 


907.18 


I 


= 


7.088 


9 


=zz 


255.146 


3 


z= 


1360.78 


* 


^rr 


14.175 


10 


— 


283.496 


4 


= 


1814.37 


1 


= 


28.350 


11 


= 


311.846 


5 


== 


2267.96 


2 


== 


56.699 


12 


z=z 


340.195 


6 


— : 


2721.55 


3 


— 


85.049 


13 


= 


368.544 


7 


= 


3175.14 


4 


- =: 


113.398 


14 


z=z 


396.894 


8 


— 


3628.74 


5 


= 


141.748 


15 


z=. 


425.243 


9 


■j=. 


4082.33 


6 





170.098 








10 





4535.92 



SPECIFIC GRAVITY. 613 

QUESTIONS AND EXERCISES. 

Mention some advantages of decimal weights and measures. — What is 
the name of the chief unit of the metric decimal system of weights and 
measures? — Mention the names of the metric units of surface, capacity, 
and weight, and state how they are derived from the unit of length. — 
How are multiples of metric units indicated? — State the designations 
of submultiples of metric units. — How many metres are there in a 
kilometre? — How many millimetres in a metre? — How many grammes 
in 5 kilogrammes? — How many milligrammes in 13^ grammes? — In 
1894 centigrammes how many grammes ? — In a metre measure 5 centi- 
metres wide and 1 centimetre thick how many cubic centimetres ? — How 
many litres are contained in a cubic metre of any liquid ? — State the 
British equivalent of the metre. — How many square yards in an are? — 
How many fluidounces in a litre? — How many ounces in a kilogramme? 
— Give the relation of a metric ton (1000 kilos) to a British ton. — How 
many grains are there in 1 British ton? — How many ounces in 1 ton? — 
How many grains of water in 1 fluidrachm? — How many minims in 
1 pint ? — How many grains in 1 pint of water ? — Whence is the British 
unit of length derived? 



Specific Weight, or Specific Gravity. 

The specific weight of a substance is its weight in comparison 
with the weights of similar bulks of other substances. This com- 
parative heaviness of solids and liquids is conventionally expressed 
in relation to water : they are considered as being lighter or heavier 
than water. Thus, water being regarded as unity = 1, the relative 
weight, or specific weight, of ether is represented by the figures 
.720 (it is nearly three-fourths, .750, the weight of water), oil of 
vitriol by 1.843 (it is nearly twice, 2.000, as heavy as water). The 
specific weight of substances is, moreover, the weight of similar 
volumes at sixty degrees (60° F.) ; for the weight of a definite 
volume of any substance will vary according to temperature, becom- 
ing heavier when cooled and lighter when heated, different bodies 
(gases excepted) differing in their rate of contraction and expan- 
sion. While, then, specific weight (or, conventionally, specific 
gravity) is truly the comparative weight of equal bulks, the numbers 
which in Great Britain commonly represent specific gravities are the 
comparative weights of equal bulks at 60° F., water being taken as 
unity .* 'The standard of comparison for gases was formerly air, 
but is now usually hydrogen. 

* The true weight of a body is its weight in air plus the weight of an 
equal bulk of air, and minus the weight of a bulk of air equal to the 
bulk of the brass or other weights employed ; or, in other words, its 
weight in vacuo uninfluenced by the buoyancy of the air ; but such a cor- 
rection of the weight of a body is seldom necessary, or, indeed, desir- 
able. Density is sometimes improperly regarded as synonymous with 
specific gravity. It is true that the density of a body is in exact propor- 
tion to its specific gravity, but the former is more correctly the compar- 
ative bulk of equal weights, while specific gravity is the comparative 
weight of equal bulks. 
27 



614 



QUANTITATIVE ANALYSIS. 



Specific Gravity of' Liquids. 

Procure any small bottle holding from 100 to 1000 grains 
(Fig. 67), and having a narrow neck ; counterpoise it in a del- 
icate balance ; fill it to about halfway up the neck with pure 
distilled water having a temperature of 60° F. ; ascertain the 
weight of the water, and, for convenience, add or subtract a 
drop or two, so that the weight shall be a round number of 
grains ; mark the neck by a diamond or file-point at the part 
cut by the lower edge of the curved surface of the water. 



Fig. 67. 



Fig. 68. 



Fig. 69. 



Fig. 70. 




Specific-gravity Bottles. 



Consecutively fill up the bottle to the neck-mark with several 
other liquids, cooled or warmed to 60° F., first rinsing out the 
bottle once or twice with a small quantity of each liquid, and 
note the weights ; the respective figures will represent the 
relative weights of equal bulks of the liquids. If the capacity 
of the bottle is 10, 100, or 1000 grains, the resulting weights 
will, without calculation, show the specific gravities of the 
liquids ; if any other number, a proportional sum must be 
worked out to ascertain the weight of the liquids as compared 
with 1 (or 1000) of water. Bottles conveniently adjusted to 
contain 250, 500, or 1000 grains, or ' 100 or 50 grammes, of 
water, when filled to the top of their perforated stopper (Fig. 
69), and other forms of the instrument (Figs. 68 and 70), are 
sold by all chemical-apparatus makers. Fig. 70 is that of a 
bottle extremely useful in ascertaining the specific gravities of 
very volatile liquids. 

Verify some of the following stated specific gravities of substances 
official in the U. S. Pharmacopoeia 1890 : 



Acid, Acetic 1.048 

" " dil 1.008 

" Glacial 1.056-1.058 
" Hydrobromic dil. . 1.077 
" Hydrochloric . . . 1.163 
" " dil. . 1.050 



Acid, Lactic 1.213 

" Nitric ...... 1.414 

" dil 1.057 

" Oleic 900 

" Phosphoric .... 1.710 
" " dil. . . 1.057 



SPECIFIC GRAVITY. 



615 



Acid, Sulphuric 1.835 

" " Aromat. . .939 

" « dil . . . 1.070 

" Sulphurous .... 1.035 

.Ether 725-.728 

Alcohol 797 

" dil 936 

Amyl Nitris 870-.880 

Aq. Ammon 960 

" Fort 901 

Bals. Peru .... 1.135-1.150 

Benzinum 670-.675 

Bromum 2.990 

Camphora 995 

Carbonei Disulphidum -J i oaq 

Cera Alba .... 0.965-0.975 

Cera Flava 955-.967 

Cetaceum 0.945 

Chloroform 1.490 

Copaiba 940-.990 

Creasote 1.070 

FelBovis 1.018-1.028 

Glycerinum 1.250 

Hydrargyrum 13.558 

Iodoformum 2.000 

Liq. Calcis 1.0015 

" Ferri Chloridi . . . 1.387 
" " Citratis . . . 1.250 

" " Nitratis . . . 1.050 

" " Subsulph. . . 1.550 

" " Tersulph. . . 1.320 

" Hydrarg. Nit 2.100 

" Plumbi Subacetatis . 1.195 

" Potassse 1.036 

" Potassii Citratis . . 1.059 
" Sodae ........ 1.059 

" " Chloratae . . . 1.052 
" Sodii Silicatis . 1.300-1.400 

" ZinciChlor 1.535 

Mel 1.101-1.105 

Oleum Adipis . . 0.910-0.920 
" ^thereum .... 0.910 
" Amygd.Amar. 1.060-1.070 
" " Express. .915-.920 
" Anisi . . . -. .980-.990 
" Aurantii Cort. . . .850 
" " Flor. .875-.890 
" Bergamottae . .880-.885 
" Cajuputi . . . .922-.929 
" Cari 910-.920 



Oleum Caryoph. . . 1.060-1067 
" Chenapodii . . . .970 
" Cinnamomi . 1.055-1.065 

" Copaiba 890 

" Coriandri 870 

" Cubebse 920 

" Erigerontis . . . .850 
" Eucalypti . . .915-.925 

" Foeniculi 960 

" Gaultherise . 1.175-1.185 
" Gossypii Sem. . .920-.930 
" Hedeomae . . .930-.940 
" Juniperi . . . .850-.890 
" Lavandulae Flor. .8S5-.897 
" Limonis . . . .858-.859 

" Lini 830-.840 

" Menth.Pip. . . .900-.920 
" " find. . .930-.940 

" Morrhuae . . .920-.925 
" Myrciae . . . .975-.990' 
" Myristicae . . .870-.900 

" Olivse 915-.918 

" Picis Liquida . . .970 
" Pimentae . . 1.045-1.055 

" Ricini 950-.970 

" Rosae 865-.880 

" Rosmarini . . .895-.915 
" Sabinee . . . .910-.940 
" Santali . . . .970-.978 
" Sassafras . . 1.070-1.090 
" Sesami . . . .919-.923 
" Sinapis vol. . 1.018-1.029 
" Terebinthinae . .855-.870 
" Thymi .... .900-.930 

" Tiglii 940-.960 

Petrolatum liquid. . . .875-945 
Phosphorus (at 50° F.) . 1.830 

Resina 1.070-1.080 

Sp. ^Etheris Nitrosi . .842-.836 

" Ammoniac 810 

" " Aromat. . .905 

•' Frumenti . . . .930-.917 
" ViniGallici . . .941-.925 

Syrupus 1.317 

Syr. Acidi Hydriodici . . 1.313 

| Thymol 1.069 

I Tinct. Ferri Chloridi . . 0.960 

Vinum Album . . . .990-1.010 

" Rubrum . . .989-1.010 

Zincum 6.9-7.2 



616 



QUANTITATIVE ANALYSIS. 



Hydrometers, formerly termed Areometers. — The specific gravity 
of liquids may be ascertained, without scales and weights, by means 
of an hydrometer, an instrument, usually of glass, having a graduated 
stem and a bulb or bulbs at the lower part. The specific gravity of 
a liquid is indicated by the depth to which the hydrometer sinks in 
the liquid, the zero of the scale marking the depth to which it sinks 
in pure water. Hydrometers constructed for special purposes are 
known under the names of saccharometer, lactometer, elseometer, 
urinometer, alcoholometer. Hydrometers require a considerable 
quantity of liquid fairly to float them, and specific gravities observed 
with them are less delicate and trustworthy than those obtained by 
the balance ; nevertheless, they are exceedingly useful for many 
practical purposes where the employment of a delicate balance 
would be inadmissible. 

Specific Gravity op Solids in Mass. 

Weigh a piece (50 to 250 grains) of any solid substance 
heavier than water in the usual manner. Then weigh it in 
•water, by suspending it from a shortened balance-pan by a fine 
thread or hair and immersing in a vessel of water (Fig. 71). 
The buoyant properties of the water will cause the solid appar- 
ently to lose weight ; this loss in weight is the exact weight of 

Fig. 71. 




Weighing a Solid in Water. 



an equal bulk of water. The weight of the substance and the 
weight of an equal bulk of water being thus ascertained, a pro- 
portional sum shows the relative weight of the substance to 
1.000 of water. To express the same thing by rule, divide the 
•weight in air by the loss of weight in water ; the resulting 
number is the specific gravity in relation to 1 part of water, 
the conventional standard of comparison. 



SPECIFIC GRAVITY. 617 

Verify some of the following specific gravities : 

Aluminium 2.56 

Antimony * 6.71 

Bismuth 9.83 

Coins, English, gold 17.69 

" " silver ......... 10.30 

" " bronze 8.70 

Copper . '. 8.95 

Gold 19.34 

Iron 7.84 

Lead 11.36 

Magnesium 1.74 

Marble 2.70 

Phosphorus 1.77 

Platinum 21.53 

Silver 10.53 

Sulphur 2.05 

Tin 7.29 

Zinc 7.14 

Specific gravities of solid substances should be taken in water 
having a temperature of about 60° F. The body should be immersed 
about half an inch below the surface of the water ; adhering air- 
bubbles must be carefully removed ; the body must be quite insoluble 
in water. 

(For a table of the specific gravities of a large number of fatty 
and resinoid substances see the Pharmaceutical Journal for Oct. 11, 
1879.) 

Specific Gravity of Solids in Powder or Small Frag- 
ments. 

Weigh the particles ; place them in a counterpoised specific- 
gravity bottle of known capacity, and fill up with water, taking 
care that the substance is thoroughly wetted ; again weigh. 
From the combined weights of water and substance subtract 
the amount due to the substance : the residue is the weight of 
the water. Subtract this weight of water from the quantity 
which the bottle normally contains : the residue is the amount 
of water displaced by the substance. Having thus obtained 
the weights of equal bulks of water and substance, a propor- 
tional sum shows the relation of the weight of the substance 
to 1 part of water — i. e. the specific gravity. 

Or, suspend a cup, short glass tube, or bucket from a short- 
ened balance-pan ; immerse in water ; counterpoise; place the 
weighed powder in the cup, and proceed as directed for taking 
the specific gravity of a solid in mass. 

This operation may be conducted on fragments of any of the sub- 
stances the specific gravities of which are given in the foregoing 



618 QUANTITATIVE ANALYSIS. 

table, or on the powdered piece of marble the specific gravity of 
which has been taken in mass. The specific gravity of one piece of 
glass, first in mass then in powder, may be ascertained 5 the result 
should be identical. The specific gravity of shot is about 11.350; 
sand, 2.600 5 mercury, 13.56. 

Specific Gravity of Solids Soluble in Water. 

Weigh a piece of sugar or other substance soluble in water ; 
then suspend it from a balance in the usual manner, and weigh 
it in turpentine, benzol, or petroleum the specific gravity of 
which is known or has been previously determined ; the loss 
in weight is the weight of an equal bulk of the turpentine. 
Ascertain the weight of an equal bulk of water by calculation : 

Sp. gr. of m sp. gr. of m . observed m equal bulk of 
turpentine ' water ' bulk of turp. ' water. 

The exact weights of equal bulks of sugar and water being 
obtained, the weight of a bulk of sugar corresponding to 1.000 
of water is shown by a proportional sum ; in other words, 
divide the weight of sugar by that of the equal bulk of water ; 
the quotient is the specific gravity of sugar. The stated spe- 
cific gravity of sugar ranges from 1.590 to 1.607. 

Specific Gravity of Solids Lighter than Water. 

This is obtained in a manner similar to that for solids heavier 
than water ; but the light body is sunk by help of a piece of 
heavy metal, the bulk of water which the latter displaces being 
deducted from the bulk displaced by both ; the remainder is 
the weight of a bulk of water equal to the bulk of the light 
body. For instance, a piece of wood weighing 12 grammes (or 
grains, for it is assumed that the student works equally well 
with metric as with imperial weights) is tied to a piece of metal 
weighing 22 grammes, the loss of weight of the metal in water 
previously having been found to be 3 grammes. The two, 
weighing 34 grammes, are now immersed, and the loss in weight 
found to be 26 grammes. But of this loss 3 grammes have 
been proved to be due to the buoyant action of the water on 
the metal ; the remaining 23 therefore represent the same effect 
on the wood ; 23 and 12 therefore represent the weights of 
equal bulks of water and wood. As 23 are to 12, so is 1 to 
.5217. Or, shortly, as before, divide the weight in air by the 
weight of an equal bulk of water ; .5217 is the specific gravity 
of the wood. Another specimen of wood may be found to be 
three-fourths (.750) the weight of water, and others heavier. 
Cork varies from .100 to .300. 



SPECIFIC GRAVITY. 619 

The specific gravity of a very minute quantity of a heavy or light 
substance may be ascertained by noting the specific gravity of a 
fluid in which it, being insoluble, neither sinks nor swims ; or by 
immersing it in a weighed piece of paraffin whose specific gravity is 
known, noting the specific gravity of the whole and deducting the 
influence of the paraffin. 

Specific Gravity of Gases. 

This operation is similar to that for liquids. A globe exhausted 
of air and holding from 1 to 4 litres (or quarts) is suspended from 
the arm of a balance and counterpoised by a similar flask. Gases are 
introduced in succession and their weights noted. A proportional 
sum shows their specific gravity in relation to air or hydrogen, which- 
ever be taken as a standard, 

Correction of the Volume of Gases for Pressure.— The height of 
the barometer at the time of manipulation is noted. Remembering 
that " the bulk of a gas is inversely as the pressure to which it is 
subjected" (Boyle and Mariotte), a simple calculation shows the 
volume which the gas would occupy at 760 millimetres (or 29.992 
inches), the standard pressure (30 inches is sometimes adopted as 
the standard in England).* Thus, 40 volumes of a gas at 740 
millims. pressure are reduced to 39 when the pressure becomes 760 
millimetres (or 90 vols, at 29 ins. barom. become 87 vols, at 30 
inches). 

Correction of the Volume of Gases for Temperature.— This is done 
in order to ascertain what volume the gas would occupy at 0° C. 
(32° F.) or 15.5° C. (60° F.), according to the standard taken. Gases 
are equally affected by equal variations in temperature (Charles). 
They expand about 0.3665f per cent. (27-3) of their volume at the 
freezing-point of water for every C. degree (0.2036, or ^y, for every 
F. degree) (Regnault). Thus 8 volumes of gas at 0° C. will become 
8.293 at 10° C. ; for if 100 become 103.665 on being increased in 
temperature 10° C, 8 will become 8.293 (or if 100 become 102.036 
on being increased 10° F., 8 will become 8.1629). 

Vapor-density. — Vapors are those gases which condense to liquids 
at common temperatures. By the density of a vapor is meant its 
specific gravity. The density of a vapor is the ratio of any given 
volume to a similar volume of air or hydrogen at the same tempera- 
ture and pressure. But, for convenience of comparison, this experi- 
mental specific gravity is referred, by calculation as just described 

* In France the conventional standard height of the barometer is 760 
millimetres at 0° C. (32° F.) : in England it is 30 inches, the temperature 
being 60° F. 760 millims. is equivalent to 28.922 inches ; but the expan- 
sion of the metal between 32° F. and 60° F. increases the length of the 
column to 30.005 inches. The standards are therefore almost identical, 
difference in true length being counterbalanced by the temperature at 
which the length is observed. 

"I" Corrected for the difference between the mercurial and air thermo- 
meters, the coefficient of expansion of air is 0.003656 (Miller). The 
coefficient of expansion of different gases varies very slightly, being 
somewhat higher for the more liquefiable gases. 



620 QUANTITATIVE ANALYSIS. 

for permanent gases, to a temperature of 0° C, and 760 millimetres 
barom. A teaspoonful or so of liquid is placed in a weighed flask 
of about the capacity of a common tumbler and having a capillary 
neck : the flask is heated in an oil-bath to a temperature consider- 
ably above the boiling-point of the liquid ; at the moment vapor 
ceases to escape the neck is sealed by a blowpipe flame and the tem- 
perature of the bath noted ; the flask is then removed, cooled, cleaned, 
and weighed ; the height of the barometer is also taken. The neck 
of the flask is next broken off beneath the surface of water (or of 
mercury), which rushes in and fills it, and again weighed, by which 
its capacity in cub. centims. is found. From these data the volume 
of vapor yielded by a given weight of liquid is ascertained by a few 
obvious calculations. The capacity of the globe having been ascer- 
tained, the weight of an equal bulk of air* is obtained by a rule-of- 
three sum. This weight of air is deducted from the original weight 
of the flask, which gives the true weight of the glass. The weight 
of the glass is next subtracted from the weight of the flask and con- 
tained vapor (now condensed), which gives the weight of material 
used in the experiment. The volume which this weight of material 
occupied at the time of experiment is next corrected for temperature 
(to 0° C.) and pressure (760 millimetres) in the manner just de- 
scribed. The weight of a similar volume of hydrogen is next found.f 
The weights of equal volumes of hydrogen and vapor being thus 
determined, the amount of vapor corresponding to 1 of hydrogen 
(the specific gravity or vapor-density) is shown by a short calcula- 
tion. This process of finding the weight of a given volume of vapor 
is by Dumas. Gay-Lussac's consists in determining the volume of 
a given weight : it has been improved by Hofmann. An easy and 
excellent method by V. and C. Meyer consists, like that of Gay- 
Lussac, in determining the volume of the vapor of a given weight of 
a fluid or solid, but differs in the volume of the vapor being ascer- 
tained from an equal volume of air which the vapor is made to dis- 
place. (For a detailed description of this method, and a drawing of 
the apparatus, see Pharmaceutical Journal, May 17, 1879.) 

Experiment shows that the specific gravities of many gases and 
vapors on the hydrogen scale and the proportions in which they 
combine by weight are identical. Thus, chlorine is 35.5 times as 
heavy as hydrogen, and 35.5 parts unite with 1 of hydrogen to form 
hydrochloric acid gas. Hence, if the specific gravity of a gas or 
vapor is known, its combining proportion may be predicated with 

* 1 cubic centimetre of air at 0° C. and 760 millim. weighs 0.001293 
gramme. 

1 1 litre (1000 cub. centims.) of hydrogen at 0° C. and 760 millimetres 
(the barometer being at 0° C.) weighs 0.0896 gramme— a quantity some- 
times termed a crith (from Kpi0r), Icrithe, a barley-corn — figuratively, a 
small weight) ; thus a litre of oxygen weighs 16 criths, chlorine 35.5 
criths, etc. 100 cubic inches of hydrogen at 32° F. weigh 2.265 grains ; at 
60° F. 2.143 grains (the barometer being 30 ins. at 60° F. in both cases). 
100 cubic inches of air at 32° F. weigh 32.698 grains ; at 60° F., 30.935 
(barom. 30 ins. at 60° F.). 1 cubic inch of water weighs 252.458 grains 
(Chaney, 252.279) at 62° F. and 30 in. bar. 1 gallon of water contains 
277i (277.274 at 62° F.) cubic ins. 1 cubic foot contains about 65 gallons. 



FUNCTIONS OF FIXED WEIGHTS OF ELEMENTS. 621 

reasonable certainty, and vice versa. In applying this rule to gas- 
eous or vaporous compounds attention must be paid to the extent 
to which their constituent gases contract at the moment of com- 
bination or expand at the moment of decomposition. Thus steam 
is found to be composed of two volumes of hydrogen and one of 
oxygen, the three volumes of constituents condensing to two at the 
moment of combination. Hence steam may be expected to be nine 
times as heavy as hydrogen, which experiment confirms. 

These relations may be so expressed as to include both elementary 
and compound gases and vapors, thus : molecular weights and spe- 
cific weights are identical. Molecular weights represent two vol- 
umes of a gas : specific gravity conventionally represents the relative 
weight of a gas compared with one volume of hydrogen or air ; hence 
the specific gravity of a gas or vapor on the H scale is found by 
calculation on simply dividing the molecular weight by 2 : on the 
air-scale, by dividing the hydrogen numbers by 14.44. For example : 

Specific gravity. 

Molecular Molecular , * » 

Name. formula. weight. H=2. H=l. Air=l. 

Hydrogen H 2 2 2 1 .069 

Chlorine Cl 2 71 71 35.5 2.460 

Oxygen 2 32 32 16 1.108 

Nitrogen N 2 28 28 14 .970 

Steam H 2 18 18 9 .624 

Ammonia gas ... NH 3 17 17 8.5 .589 

Carbonic acid gas . . C0 2 44 44 22 1.524 

Alcohol (vapor) . . . C 2 H 6 46 46 23 1.593 

Air — — 28.88 14.44 1.000 

In other words, it follows, as an arithmetical necessity, that if 
the specific gravities of gases or vapors have been rightly deter- 
mined, and the molecular weights of those gases and vapors have 
been quite accurately ascertained, the product of the division of the 
figures showing the molecular weights by the figures showing the 
specific gravities will be quotients that will always be the same 
number. If the specific gravity be in relation to two volumes of 
hydrogen, the quotient will in all cases be the figure 1, or, obviously, 
the figures for specific gravity and molecular weight will be identi- 
cal. If the specific-gravity figure be in relation to one volume of 
hydrogen, the quotient will be the figure 2 ; if in relation to air, 
the quotient will be 28.88 (air being 14.44 times heavier than hydro- 
gen). By multiplying 28.88 by the specific gravity on the air-scale 
the experimental figure obtained for molecular weight can be checked. 
So by dividing the molecular weight by 28.88 the specific gravity 
on the air-scale can be checked. Once more, divide the molecular 
weight by the specific gravity on the air-scale, and the quotient will 
not be far from 28.88 if the two figures have been ascertained with 
all attainable experimental exactitude. 

The foregoing columns of specific gravities closely correspond with 
those obtained by actual experiment. The specific gravity of any 
gas or vapor may therefore be calculated if the following data are 
at hand: (a) formula, (b) atomic weight of constituent elements: 



622 QUANTITATIVE ANALYSIS. 

these give the molecular weight, and the molecular weight divided 
by 2 is the specific gravity on the hydrogen scale. Specific gravity 
on the air-scale is then deducible, if (c) the specific gravity of air 
(14.44) in relation to hydrogen be remembered. The absolute 
weight of any volume of a gas or vapor on the metric system is then 
obtainable if (d) the weight of a litre of hydrogen (0.0896 gramme) 
be known, or on the English plan by remembering (e) that 100 
cubic inches of hydrogen at 60° F. weigh 2.143 grains (100 cubic 
inches of air at 60° F. weigh 30.935 grains). 

In confirmation of these statements regarding the mutual relation 
of specific gravity and atomic weight a remarkable fact may be men- 
tioned. Regnault several years ago found the weight of 1 litre of 
hydrogen and oxygen to be respectively .089578 gramme and 1.429802 
grammes. The latter number divided by the former gives 15.96 as 
the specific gravity of oxygen. Stas, in recent experimental re- 
searches on combining proportion, finds the atomic weight of oxygen 
to be not 16, but 15.96. 

Exceptions to the law occur in a few compounds and in arsenum 
and phosphorus, whose vapor densities are twice that indicated by 
the rule. Possibly in these cases the temperature employed is insuf- 
ficient to dissociate an unusually complex molecule into molecules 
of usual complexity. As regards compounds, and possibly as re- 
gards those elements in which the observed density is only half 
that indicated by this rule, heat may, and in some cases probably 
does, produce molecular dissociation (thermolysis) into free atoms 
(uniatomic molecules) or into less complex molecules. (See p. 195.) 

Relation of the Specific Seat of Elements to their Atomic Weights. 
— Reference may here appropriately be made to a physical fact of 
great importance as regards molecular and atomic weights. In the 
earlier pages of this Manual it was stated that elements do not com- 
bine chemically in haphazard proportions, but in fixed weights ; 
and abundant evidence of the truth of the statement has already 
been afforded, and will also be found in this section on quanti- 
tative analysis. Secondly, it has been shown that elements do 
not combine in haphazard proportions by volume, but in certain 
constant bulks ; and the weights of these bulks have been found to 
be identical with the combining weights themselves. Thirdly (this 
is the point to which attention is now drawn), if equal amounts of 
heat be given to the elements in the solid state (that is, to solid 
elements or to solid compounds of volatile elements), and the quan- 
tity of the element be increased or diminished until each is thus 
heated through an equal number of degrees, it will be found that 
the different weights of elements required are (in relation to a com- 
mon standard) identical with the combining weights of the elements 
and with the weights of the combining volumes of the elements. 
Thus, where 108 parts of silver would be employed 207 of lead 
would be necessary * Hence, in the determination of (a) combining 

* Obviously, if equal weights of silver and lead were heated through 
an equal number of degrees, the silver would absorb nearly twice as 
much heat as the lead. In fact, as regards all the solid elements " spe- 
cific heats and atomic weights are inversely proportional." This law 






QUESTIONS AND EXEECISES. 623 

proportion, (6) specific gravity in gaseous state, and (c) specific heat, 
three distinct methods of ascertaining atomic weight are available. 
In cases where one method is inapplicable recourse is had to either, 
or, if practicable, both of the others, and thus the trustworthiness 
of observations and generalizations placed more or less beyond 
question. The specific heat of a solid element is the same in the 
free as in the combined condition ; therefore the specific heat of a 
molecule is the sum of the specific heats of its constituent atoms. 
From the specific heat of a solid compound of a volatile element 
(chlorine, for example) can thus be calculated the specific heat of 
an element in the solid state, even though the free element cannot 
itself be solidified. For the processes by which experimentally to 
determine specific heat the reader is referred to books on Physics. 

There is equivalency also between electrical and chemical action. 
The amount of electricity which, passed through an iodide, would, 
by the resulting electrolysis (electric loosing, from Tivo, luo, to decom- 
pose), set free 127 parts of iodine, would set free 80 parts of bromine. 

Again, Raoult, reflecting that the degree to which the solidifying 
point of a fluid is affected by a dissolved substance is dependent on 
the molecular weight of that substance, has shown that determi- 
nations of such degrees point to molecular weights. (Further 
researches in this direction will probably throw much light on the 
nature of the phenomena of solution.) Optical activity and molec- 
ular weight would also seem to be interdependent. 






QUESTIONS AND EXEECISES. 

Define specific weight, or, as it is commonly termed, specific gravity. — 
In speaking of light and heavy bodies specifically, what standard of 
comparison is conventionally employed ?— How are specific gravities 
expressed in figures? — Why should specific gravities be taken at one 
constant temperature ? — How does the buoyancy of air affect the real 
weight of any material ? — Describe the difference between density and 
specific gravity. — Give a direct method for taking the specific gravity of 
liquids. — A certain bottle holds 150 parts, by weight, of water, or 135.7 
of spirit of wine ; show that the specific gravity of the latter is 0.9046. 
— An imperial fluidounce of a liquid weighs 366£ grains; prove that its 
specific gravity is 0.838. — Equal volumes of benzol and glycerin weigh 
34 and 49 parts respectively, and the specific gravity of the benzol is 
0.850 ; show that the specific gravity of the glycerin is 1.225. — Explain 
the process employed in taking the specific gravity of solid substances 
in mass and in powder. — State the method by which the specific gravity 
of a light body, such as cork, is obtained. — What modifications of the 
usual method are necessary in ascertaining the specific gravity of sub- 
stances soluble in water ? — How is the specific gravity of gases deter- 

was discovered by Dulong and Petit. It follows that the product of the 
multiplication of the figures representing the specific heat of an element 
with the figures representing its atomic weight is in the case of nearly 
every such element the same number — namely 6, more or less according 
to the care with which the experiments have been conducted. Some 
exceptions to the law have disappeared when the experiments have been 
conducted at a sufficiently high temperature. 



624 QUANTITATIVE ANALYSIS. 

mined ? — By what law can the volume of a gas, at any required pressure, 
be deduced from its observed volume at another pressure? — To what 
extent will 78 volumes of a gas at 29.3 inches barom. alter in bulk when 
the pressure is 30.2 inches? — Write a short account of the means by 
which the volumes of gases are corrected for temperature. — At the tem- 
perature of 15° C. 40 volumes (litres, pints, ounces, cubic feet, or other 
quantity) of a gas are measured. To what extent will this amount of 
gas contract on being cooled to the freezing-point of water (0° C.)? 
Answer: As 1 vol. of any gas at zero expands or contracts .003665 of a 
vol. for each rise or fall of 1° C, 1 vol. at 0° C. if heated to 15° C. will 
become increased by .054975 (that is, .003665 multiplied by 15) ; 1 vol. 
will expand to 1.054975. Conversely, 1.054975 vol. will contract to 1 vol. 
if cooled from 15° C. to 0° C. And if 1.054975 becomes 1 in cooling 
through 15° C, 40 vols, will (as found by rule of three) contract to 
37.916. — 10 litres of oxygen are measured off at 14° F. Required the 
volume of the gas at 15° C. Answer: The first operation must be to 
reduce the temperature quoted in Fahrenheit's degrees to an equivalent 
value on the Centigrade scale. 14° F. is 18° below 32° F., the freezing- 
point of water; and a range of 9° on the Fahrenheit scale is equal to 
a range of 5° on the Centigrade scale, so that the temperature at which 
the oxygen is measured off is — 10° C. The rise of temperature up to 0° 
expands the gas in such proportion that its volume at 0° is to its volume 
at - 10° as 1 is to 1 - 0.03665, i. e. as 1 to 0.96335. The further rise of 
temperature from 0° C. to 15° expands the gas in the proportion of 1 to 
1 + 15 X 0.003665, i. e. 1 to 1.054975. The total rise of temperature there- 
fore expands the gas in the proportion qf 0.96335 to 1.054975. 

0.96335 : 1.054975 :: 10 : x; 
10 X 1.054975 



0.96335 



10.95. 



— 230 cubic centimetres of oxygen are measured off at 14° C. and 740 mil- 
limetres mercurial pressure. Eequired the volume of the gas at the 
normal temperature and pressure (0° C. and 760 millimetres). Answer: 
Let the reduction for change of temperature be made first. The pro- 
portion — 

1 + (14X0.003665) : 1 : : 230 : x 
gives 

To reduce this volume at 740 millimetres pressure to the volume corre- 
sponding to the pressure of 760 millimetres, we have the proportion — 

760 : 740 : : 218.77 : x ; 
whence 

740 X 218.77 



760 



213.02. 



— A litre of oxygen is confined in a glass flask at 10° C. by the atmo- 
spheric pressure, added to that of a column of mercury 60 millimetres 
high. The flask must be heated to 300° C. without any increase of 
volume taking place in the oxygen. How high must the column of 
mercury then be which presses on the gas, supposing the atmospheric 
pressure to remain constant at 760 millimetres? Answer : The oxygen is 
given at 10° C. and 820 millimetres pressure. If the pressure remain 
constant, the rise of temperature from 10° C. to 300° C. would expand 
the gas in such proportiou that 1.03665 volumes would expand to 2.0995 



QUESTIONS AND EXERCISES. 625 

volumes. In order to prevent any expansion the pressure must be 
increased in the same proportion, whence 



1.03665 : 2.0995 : : 820 
820 X 2.0995 



1.03665 



* 1660. 






From this total pressure the atmospheric pressure of 760 millimetres has 
to be deducted, leaving 900.6 millimetres as the height of the required 
mercurial column. — A litre of oxygen is required of the density of 100 
at 0° C. What weight of potassic chlorate must be used for its prepara- 
tion, and what total pressure must be applied to it? Answer: The 
pressure required to compress oxygen from the density of 16 to that of 
100 is found by the proportion — 

16 : 100 :: 760 : x; 

.-. *=™™ 4750. 
lb 

At the pressure of 4750 millimetres of mercury the weight of a litre of 
oxygen (16 grammes measure 11.2 litres at 0° C. and 760 millims. pres- 
sure) is found by the proportion — 

760:4750:: ni : * ; 

whence 

„ 16 X 4750 _ no 

8.93 grammes. 



11.2 X 760 

The weight of chlorate required for the evolution of 8.93 grammes of 
oxygen is found from the proportion — 

48 : 122.5 : : 8.93 : x ; 

. ' . x = 22.8 grammes. 

— What is the volume of 12 grammes of hydrogen at 15° C. ? Answer: 
1 gramme of hydrogen measures 11.2 litres at 0° C. ; therefore 12 
grammes measure 12 X 11.2 = 134.4 litres at 0°. To find their volume 
at 15° C. we have the proportion— 

1 : 1 + 15 X 0.003665 : : 134.4 : x ; 
whence 

* = 134.4 X 1.054975 = 141.788 litres. 

(The foregoing five problems are from Williamson's "Chemistry.") 
— What interest for chemists have the specific heats of substances? 



VOLUMETRIC QUANTITATIVE ANALYSIS. 

Preliminary Note. — Great care should be observed in select- 
ing dbfair sample of any bulk of material that is to be exam- 
ined either by volumetric or gravimetric quantitative analysis. 
If the whole quantity is in separate parcels, and there is any 
ground for believing that the parcels differ in quality, they 
should, if practicable, be carefully mixed, or, technically, 



626 VOLUMETRIC QUANTITATIVE ANALYSIS. 

" bulked." Small portions should be taken from different parts 
of the resulting heap and well mixed in a mortar or other ves- 
sel, or, in certain cases, dissolved and the solution well stirred 
or shaken. A specimen of the powder or a portion of the 
solution may then be selected for analysis. 

Introduction. — The operations of volumetric analysis consist 
(a) in carrying out some definite chemical reaction, already well 
known to the operator, with (6) definite quantities of substances 
or salts ; (c) the exact termination of the reaction between the 
two salts or substances being ascertained, usually by some chemical 
indicator (litmus, starch, etc.). A portion of the substance or salt, 
etc. to be tested is carefully weighed. To this is gradually added 
the second substance or salt contained in the testing fluid, com- 
monly termed the Standard Volumetric Solution. The usefulness, 
and, indeed, the preparation, of this standard solution is founded 
(as already indicated on p. 592) on some accurate initial gravi- 
metric operation. A weighed amount of a pure salt is dissolved 
in a given volume of water. " Accurately measured quantities of 
such a standard volumetric solution will obviously contain just as 
definite amounts of the dissolved salt as if those amounts were 
actually weighed in a balance, and as measuring occupies less time 
than weighing, the volumetric operations can be conducted with 
great economy of time as compared with the corresponding gravi- 
metric operations." 

Normal solutions contain (a) one molecular weight in grammes, 
per litre, of substances, the molecular weights of which are 
chemically comparable with one atomic weight of hydrogen 
(e.g. HC1 = 36.37,K0H = 55.99, etc.), or (6) such a proportion of 
the molecular weight as in the volumetric reactions is comparable with 
one atomic weight of hydrogen (e. g. H 2 S0 4 = 97.82 — 2 = 48.91, or 
K 2 Mn 2 8 = 315.34 -7- 10 = 31.534). Decinormal solutions are one- 
tenth (^) the strength of normal solutions ; centinormal (j^), one- 
hundredth ; seminormal (|Y one-half; double-normal Q), twice; 
and so on. 

APPARATUS. 

The only special vessels necessary in volumetric quantitative 
operations are — 1. A litre flask (Fig. 73), which, when filled to a 
mark on the neck, contains, at about 15° C. or 60° F., 1 litre (1000 
cubic centimetres — i.e. 1000 grammes) of water;* it serves for 
preparing solutions in quantities of 1 litre. 2. A tall, cylindrical 
graduated litre jar (Fig. 72) divided into one hundred equal parts; 
it serves for the measurement and admixture of decimal or centesimal 
parts of 1 litre. 3. A graduated tube or burette (Fig. 74), the 
marked portion of which, when filled to "0," holds 100 cubic centi-. 

* A cubic centimetre is, strictly speaking, the volume occupied by 1 
gramme of distilled water at its point of greatest density — namely, 4° C. 
Metric measurements, however, are uniformly taken at 15° or 15.55° C. 

(59° or 60° F.). 



APPARATUS. 



627 



metres, and is divided into one hundred equal parts, with subdi- 
visions ; it is used for accurately measuring small volumes of 
liquids. 

The best form of burette is Mohr's. It consists of a glass tube, 
commonly about the width of a little finger and the length of an arm 



Fig. 72. 



Fig. 73. 




A Litre Jar. 



A Litre Flask. 



A Burette, etc. 



from the elbow, contracted at the lower extremity and graduated. 
The width and length of burettes, however, as well as the extent 
and -fineness of their graduation, vary considerably. To the con- 
tracted portion is fitted a small piece of vulcanized caoutchouc 
tubing, into the other end of whiqh a small spout made of narrow 
glass tube is tightly inserted. A strong wire clamp effectually pre- 
vents any liquid from passing out of the burette unless the knobs 
of the clamp are pressed by the finger and thumb of the operator, 
when a stream or drops flow at will. Avoid accumulation of air 
behind the india-rubber. In place of the india-rubber tubing 
and clamp, a stopcock is often employed, - and is to be preferred, 
though other modes of arresting the flow of liquid may be 
adopted. The accurate reading of the height of a solution in the 
burette is a matter of great importance : it should be taken from 
the bottom of the curved surface of the liquid. It may be still 
more exactly measured by the employment of a hollow glass float or 
bulb (Erdmann's float, see Fig. 74), of such a width that it can 
move freely in the tube without undue friction, and so adjusted in 
weight that it shall sink to more than half its length in any ordinary 
liquid. A fine line is scratched round the centre of the float ^ this 
line must always be regarded as marking the height of the fluid in 
the burette. In charging the burette a solution is poured in, not 
until its surface is coincident with 0, but until the mark on the float 
is coincident with 0. •■'.-■ 



628 VOLUMETRIC QUANTITATIVE ANALYSIS. 

ESTIMATION OF ALKALIES, ETC. 

(Volumetric Solutions of Sulphuric Acid, H 2 S0 4 = 97.82.) 

The sulphuric radical being bivalent, and most of the metals 
contained in the salts which are estimated by sulphuric acid being 
univalent, it is convenient that each litre of this solution should 
contain half a molecular weight in grammes of the acid (H 2 S0 4 = 
97.82 -t-2 = 48.91). This is the " Normal Sulphuric Acid." 

The standard sulphuric-acid solution is prepared by diluting oil 
of vitriol with three or four times its bulk of distilled water, and 
then determining the strength of this solution by titration with pure 
sodium carbonate, making use of the following memoranda : 

Na 2 C0 3 + H 2 S0 4 = Na 2 S0 4 + C0 2 + H 2 

2)106 2)97.82 
53 48.91 

Pure anhydrous sodium carbonate is easy to obtain, for commercial 
bicarbonate is usually of such purity that when a few grammes are 
heated to redness for a quarter of an hour the resulting carbonate 
is practically free from impurity. The bicarbonate should, however, 
be tested, and if more than traces of chlorides and sulphates are 
present, these may be removed by washing a few hundred grammes, 
first with a saturated solution of sodium bicarbonate, and afterward 
with pure distilled water. After drying, the salt is ready for 
ignition. 

About half a gramme of the sodium carbonate is accurately 
weighed and placed in a half-litre flask, around the neck of which is 
tied calico or leather to protect the fingers when the heated vessel is 
shaken by the operator. The salt is dissolved in water to about one- 
third the capacity of the flask, and a few drops of the indicator, blue 
tincture of litmus, is added. The acid solution to be " set " or 
" standardized " is then poured into a burette, and run therefrom 
into the flask until the reddened litmus indicates the presence of free 
acid. This will be due in the first place to carbonic acid liberated 
and remaining dissolved in the solution. The contents of the flask 
are therefore boiled for several minutes, when the blue color will 
have returned. More acid is then run in until the mixture, after 
boiling, remains of a neutral color, indicating that just enough acid 
has been added to complete the reaction expressed in the foregoing 
equation. 

Let it be supposed that .6 of a gramme of sodium carbonate was 
taken, and that this required 11 cc. of the sulphuric-acid solution : 
how many cc. of this solution would contain 48.91 grammes of pure 
sulphuric acid? or, what is equivalent in the reaction, how many 
cc. would be required to neutralize 53 grammes of sodium carbonate ? 
As .6 of a gramme of the carbonate is to 11 cc. of solution, so are 
53 grammes of the carbonate to x cc. of solution ; therefore x = 
972 cc. 972 cc. (nearly) are equivalent to 53 grammes of sodium 
carbonate, and contain 48.91 grammes of pure sulphuric acid. 

This sulphuric-acid solution may be used as it is, or may be 



etc. 629 

diluted with water, every 972 cc. to be diluted to 1000 cc., so that 
1000 cc. shall contain 48.91 grammes of sulphuric acid. 

The following official substances are tested by this solution ac- 
cording to the United States Pharmacopoeia: 

Solutions of Ammonia. — 2 or 3 grammes of dilute, or about 1 
gramme of strong, solution of ammonia is a convenient quantity to 
operate upon. The weighing is most conveniently accomplished by 
taking a small stoppered bottle containing half an ounce or so of the 
substance, and having ascertained its total weight, transfer about the 
quantity desired to the flask in which the estimation is to be con- 
ducted, and again weigh the bottle with what remains in it. The 
difference is the exact quantity taken. The weighing of the ammo- 
nia solution having been accomplished, water is added, to about one- 
third the capacity of the flask (or, better, the ammonia is added to 
water already in the flask), and a few drops of tincture of litmus 
are introduced. The titration is then conducted as described before, 
except that no heat is employed. 

2NH 4 HO + H 2 S0 4 = (NH 4 ) 2 S0 4 + 2H 2 
2)70 2)97.82 

35 48.91 = grammes in 1000 cc. of standard solution. 

2NH 3 H 2 + H 2 S0 4 = (NHJ 2 S0 4 + 2H 2 

2 )97.82 

48.91 = grammes in 1000 cc. of standard solution. 

1000 cc. of standard solution, or its equivalent of a solution of 
any other strength, would, according to this reaction, neutralize 17 
grammes of ammonia gas (NH 3 ) or 35 grammes of ammonium 
hydrate (NH 4 HO). If 3 grammes of ammonia solution had been 
taken, and it had required 15 cc. of standard oxalic-acid solution, 
then the amount of ammonia gas or ammonium hydrate it contained 
would be seen by the following calculations : 

1000 cc. : 17NH 3 : : 15 cc. : x = .255 grammes NH 3 
1000 cc. : 35NHJIO : : 15 cc. : x = .525 grammes NH 4 HO 

3 grammes, then, would contain .255 grammes of the gas, or .525 
grammes of ammonium hydrate. Or in percentage : 

3gr.sol.:.255gr.NH 3 : :100gr.sol. : xgr. NH 3 = 8.5%NH 3 
3 gr. sol. : .525 gr. NH 4 HO : : 100 gr. sol. : x gr. NH 4 HO =17.5% NH 4 HO 

The solution would therefore contain 8.5 per cent, of ammonia gas 
(NH 3 ) or 17.5 per cent, of ammonium hydrate (NH 4 HO). If the 
sulphuric-acid solution was not of the full standard, the number of 
cc. which contained 48.91 grammes of pure sulphuric acid — which 
was, in fact, equivalent to 1000 cc. of standard solution — would be 
substituted for 1000 cc. in the preceding proportions. 

A comparison should now be made with the requirements of the 
Pharmacopoeia. It is useful to express results as percentage of sub- 
stance of pharmacopoeial strength in the material examined. Thus 




630 VOLUMETRIC QUANTITATIVE ANALYSIS. 

the U. S. Pharmacopoeia requires dilute ammonia solution (both 
Aqua Ammonice and Spiritus Ammonice) to contain 10 per cent, of 
the gas (NH 3 ). The solution supposed to have been operated on 
contained 8.5 per cent. NH 3 (10:8.5: : 100:a7 = 85). Therefore it 
contains 85 per cent, of the dilute ammonia of the U. S. Pharma- 
copoeia.* 

Strong Solution of Ammonia, U. S. P., contains 28 per cent, of 
ammonia gas (NH 3 ). 

Note. — The calculations just described for ammonia are similar to 
those employed throughout Volumetric Analysis ; they will not be 
repeated, therefore, in the case of every substance. 

Ammonium Carbonate.— -The reactions indicated by the following 
equations occur between commercial ammonium carbonate and sul- 
phuric acid : 

2N 3 H n C 2 5 + 3H 2 S0 4 = 3(NH 4 ) 2 S0 4 + 6H 2 + 4C(> 2 

6 )314 6) 293.46 

52.3 48.91 

About 1 gramme is a convenient quantity to operate upon. If 
tincture of litmus be the indicator, the titration should be conducted 
at a temperature just short of boiling. The estimation is not very 
satisfactory, because the heat employed, while scarcely sufficient to 
expel the carbonic acid gas, is enough to occasion loss of ammoniacal 
salt. Practised analysts usually add excess of the standard acid, 
and thus fix every trace of ammonia ; then gently boil to get rid of 
carbonic acid gas ; bring back the liquid to neutrality by an observed 
volume of standard alkaline solution, and deduct an equivalent 
volume of acid from the quantity first added. The United States 
Pharmacopoeia, however, orders the use of methyl-orange in place 
of litmus, which obviates the difficulty just mentioned. According 

* Extremely minute quantities of ammonia — 1 part in many millions 
of water — may be estimated volumetrically by adding excess of a color- 
less, strongly alkaline solution of red mercury iodide ( Nessler' s test), 
then in a similar vessel, containing an equal amount of pure water with 
excess of the Nessler reagent, imitating the depth of yellow or reddish- 
yellow color thus produced by adding an ammoniacal solution of known 
strength. The amount of ammonia thus added represents the amount in 
the original liquid. 

The Nessler Reagent. — A litre may be made by dissolving 30 or 40 
grammes of potassium iodide in a small quantity of hot water, adding a 
strong hot solution of mercury perchloride until the precipitate of mer- 
curic iodide ceases to redissolve even by the aid of rapid stirring and 
heat, slightly diluting, filtering, adding a strong solution of (120 to 140 
grammes) caustic soda or (160 to 180 grammes) caustic potash, and dilut- 
ing to 1 litre. A few cc. (5 or 6 or more) of a strong solution of mercury 
perchloride are finally stirred in, the whole set aside till all precipitated 
red iodide has deposited, and the clear liquid decanted for use. The 
reaction of this Nessler test with ammonia is as follows : 

NH 3 + 2HgI 2 + 3KHO — NHg 2 I + 3KI + 3H a O. 

Potassio-mercuric iodide, without alkali, is commonly known as 
Mayer's Reagent, Hgl22KI. 



631 

to official requirements, 5.23 grammes neutralize 100 cc. of the 
standard solution of sulphuric acid. This corresponds to 100 per 
cent, of carbonate having the formula N 3 H n C 2 5 . 

Lead Acetate and Solution of Subacetate. — Operate upon about 3 
grammes of lead acetate and from 5 to 10 grammes of solution of 
subacetate. 

Pb2C 2 H 3 2 ,3H 2 + H 2 S0 4 = PbSO, + 2HC 2 H 3 2 + 3H 2 

2)379~ 2 )97.82 

189.5 48.91 = grammes in 1000 cc. of standard solution. 

Pb 2 02C 2 H 3 2 + 2H 2 S0 4 = 2PbS0 4 + 2HC 2 H 3 2 + H 2 
4)548~~ 4 )195.64 

137 48.91 = grammes in 1000 cc. of standard solution. 

The flask in which the estimation is being conducted should pre- 
viously contain one-third of water. In the case of both lead acetate 
and solution of subacetate a little acetic acid should be added to 
prevent precipitation of basic salt on dilution. The only indicator 
of complete reaction is cessation of production of the precipitate — 
lead sulphate. The British Pharmacopoeia requires lead acetate to 
be pure (100 per cent.), and the U. S. P. requires the subacetate 
solution to contain 25 per cent. 

Sodium, Caustic Potash and Soda, Potassium and Sodium Car- 
bonates and Bicarbonates. — Methyl-orange is the indicator through- 
out, for the caustic alkalies always contain some carbonate. 

Na 2 + H 2 S0 4 = H 2 + Na 2 SO, 
2)46 2 )97.82 

23 48.91 = grammes in 1000 cc. of standard solution. 

2KHO 4- H 2 S0 4 = K 2 S0 4 4- 2H 2 
2 )112 2)97.82 

56 48.91 = grammes in 1000 cc. of standard solution. 

2NaHO 4- H 2 S0 4 = Na 2 SO, 4- 2H 2 



Or 



2)80 2 )97.82 

40 48.91 = grammes in 1000 cc. of standard solution. 

K 2 C0 3 4- 16 % H 2 4- H 2 S0 4 == K 2 S0 4 + C0 2 4- *H 2 
2 )164.28 2 )97.82 

82.14 48.91 = grammes in 1000 cc. of standard solution. 

Na 2 C0 3 -f- H 2 SO, = Na 2 SO, 4- C0 2 4- H 2 
2)106 2)97.82 

53 48.91 = grammes in 1000 cc. of standard solution. 



632 VOLUMETRIC QUANTITATIVE ANALYSIS. 

Or, 

Na 2 CO 3 ,10H 2 O + H 2 S0 4 = Na 2 S0 4 + C0 2 + 11H 2 

2)286~ 2 )97.82 

143 48.91 = grammes in 1000 cc. of standard solution. 

2KHC0 3 + H 2 S0 4 = K 2 SO, + 2C0 2 + 2H 2 
2)200 2 )97.82 

100 48.91 = grammes in 1000 cc. of standard solution. 

2NaHC0 3 + H 2 S0 4 = Na 2 S0 4 + 2C0 2 + 2H 2 
2)168 2)97.82 

84 48.91 = grammes in 1000 cc. of standard solution. 

Convenient quantities to operate with are — of caustic potash, 1 
gramme ; caustic soda, .5 to 1 gramme ; potassium carbonate or 
bicarbonate, 1 to 2 grammes ; sodium carbonate or bicarbonate, 2 to 
3 grammes ; dried sodium carbonate, .5 to 1 gramme ; and of solu- 
tions a corresponding quantity. The United States Pharmacopoeial 
requirements are — caustic potash or soda, 90 per cent, of KHO or 
NaHO ; potassium carbonate, 95 per cent, of the anhydrous salt 5 
anhydrous sodium carbonate, 98.9 per cent. ; dried sodium carbonate, 
73 per cent. •, sodium bicarbonate, 98.6 per cent. Liquor Potassce 
and Liquor Sodce, U. S. P., must contain 5 per cent, of pure hydrate. 

The strength of soda-ash is often reported in terms of " soda" — 
that is, oxide of sodium (Na 2 = 62). The old molecular weight 
of sodium carbonate, 54 (it should have been 53), derived from that 
of "soda," 32 (it should have been 31), is still employed in Great 
Britain in reporting the strength of soda-ash. The true amount of 
soda equivalent to 54 parts of carbonate is 31.41 parts. A modern 
analyst, having found the true amount of soda in a sample of- soda- 
ash, is expected by some manufacturers to report 31 as 31.41 parts, 
or 53 of carbonate as 54, and other quantities in proportion to these 
figures. 

Potassium and Sodium Tartrates and Citrates. — "When tartrates 
or citrates of alkali-metals are burned in the open air, the whole of 
the metal remains in the form of carbonate. Each molecular weight 
of a neutral tartrate gives one molecular weight of carbonate, and 
every two molecular weights of an acid tartrate give one molecular 
weight of carbonate. Advantage is taken of these reactions to esti- 
mate indirectly the quantity of citrate or tartrate in presence of 
substances with which they are generally associated. 1 or 2 
grammes of any of these salts is a convenient quantity to operate 
upon. The ignition may be conducted in a platinum or porcelain 
crucible. A low red heat only should be used, and the vessel re- 
moved when complete carbonization has been effected ; that is to 
say, when nothing remains but the carbonate and free carbon. The 
mixture is in this case treated with hot water and the carbon sep- 
arated by filtration. If too little heat has been used and carboniza- 
tion is not complete, the filtrate will be more or less colored. If 



etc. 633 

this should be the case, the operation must be repeated with a fresh 
quantity of material. The carbonate is titrated in the usual way. 
The following equations, etc. explain the reactions : 

2(K 2 C 4 H 4 6 ,H 2 0) + 5 () 2 = 2K 2 C0 3 + 6C0 2 + 4H 2 
4)488~ 4 )276 

] 22 69 equiv. to 1000 cc. of stand, sulphuric acid. 

(2KHC 4 H 4 6 + 50 2 = K 2 C0 3 + 7C0 2 + 5H 2 

2)376 2 )138 

188 69 equiv. to 1000 cc. of standard sulphuric acid. 

2K 3 C 6 H 5 o 7 + 90 2 = 3K 2 C0 3 + 9C0 2 + 5H 2 
6)612 6)414 

.102 69 equiv. to 1000 cc. of standard sulphuric acid. 

2(KNaC 4 H 4 6 ,4H 2 0) + 50 2 = 2KNaC0 3 + 6C0 2 + 12H 2 
4)564 4)244 

141 ai equiv. to 1000 cc. of standard sul- 

phuric acid. 

It will be readily understood that in the first (for example) of the 
reactions just expressed 122 weights of potassium tartrate are equiv- 
alent to 69 weights of potassium carbonate ; and as in a previous 
reaction it has been shown that 69 weights of potassium carbonate 
are equivalent to 48.91 grammes of pure H 2 S0 4 , it follows that 122 
weights of potassium tartrate are equivalent to 48.91 grammes of 
sulphuric acid. Let these weights be grammes, and then 122 
grammes of potassium tartrate are equivalent to 48.91 grammes 
of sulphuric acid or to 1000 cc* of the standard solution of sul- 
phuric acid. If the substance estimated be a crude sample of 
potassium tartrate, and the number of cc. of sulphuric acid used 
has been 15 cc, then as 1000 cc. of the acid solution are to 122 
grammes of potassium tartrate, so are 15 cc. of the solution to 
1.830 grammes of potassium tartrate. Now, if the weight of the 
sample taken was 2 grammes, then as 2 grammes of the sample 
contain 1.830 of real potassium tartrate, 100 will contain x = 91.5 
per cent, of real tartrate. These salts are required to be 100 per 
cent, pure by the United States Pharmacopoeia, except potassium 
acetate, which is to have 98 per cent, of real acetate. Trade sam- 
ples are practically pure, as a rule. If calcium sulphate be present 
in tartrates or citrates, loss of potassium carbonate will ensue, 
potassium sulphate being formed. In estimating potassium acid 
tartrate, which is the salt most likely to contain calcium sulphate, 
direct titration without ignition may be followed. 

Strontium Lactate. — To estimate this substance the strontium lactate 
is dried at 100° F., and a small quantity taken — say about 1£ grammes. 
This is then ignited, as in the case of Rochelle salt, and the resi- 
due dissolved in water and titrated with normal sulphuric acid, 



634 VOLUMETRIC QUANTITATIVE ANALYSIS. 

methyl-orange as the indicator. The equation will explain the 
reaction : 

Sr(C 3 H 5 3 ) 2 + 50 2 = SrC0 3 + 4C0 2 + 5H 2 
2 )265.3 2 )147.3 

132.65 73.65 equiv. to 1000 cc. of normal sulphuric acid. 

The official substance should contain 98.6 per cent, of pure stron- 
tium lactate. 

Lithium Carbonate, Benzoate, Citrate, and Salicylate. — All these 
substances may be estimated on the principles (by ignition, etc.) 
which have been explained in the case of sodium and potassium 
salts. The following equations will aid the student : 

Li 2 C0 3 -f H 2 S0 4 == Li 2 S0 4 + H 2 + C0 2 
2) 73.87 2 )97.82 

36.94 48.91 = grammes in 1000 cc. of standard solution. 

2LiC 7 H 5 2 + 150 2 = Li 2 C0 3 + 13C0 2 + 5H 2 

2)127V72 2)73.87 

63.86 36.94 equiv. to 1000 cc. of normal sulphuric acid. 

2Li 3 C 6 H 5 7 -f 90 2 = 3Li 2 C0 3 + 9C0 2 + 5H 2 



6)419.14 6 )321.61 

69.86 36.94 equiv. to 1000 cc. of normal sulphuric acid. 

2LiC 7 H 5 3 + 140 2 = Li 2 C0 3 + 13C0 2 + 5H 2 

2)287.36 2)73.87 

143.68 36.94 equiv. to 1000 cc. of normal sulphuric acid. 

In the case of the last three the residues, after ignition, are dis- 
solved in water and titrated. It will be easily seen, on looking 
through the above equations, that in all four cases the lithium car- 
bonate is being directly estimated, and indirectly the respective 
salts. The Pharmacopoeia (U. S. P.) requires the carbonate to con- 
tain 98.98 per cent, of the pure salt, the benzoate 99.6, the citrate 
99.2, and the salicylate 99.13 per cent, of the pure salt. 

Decinormal Sulphuric Acid is sometimes more convenient to use 
than normal 1000 cc. = 4.891 grammes of sulphuric acid. 

Volumetric Solution of Oxalic Acid. 

(Crystallized Oxalic Acid, H 2 C 2 4 ,2H 2 = 125.7.) 

Standard Oxalic Acid may be used in the place of sulphuric acid. 

If pure crystallized oxalic acid be at hand, the normal solution is 

made by dissolving 62.85 grammes in water, and making the volume 

up with more water to exactly 1 litre. 

Pure oxalic acid, however, not being easy to obtain, the solution 
may be made from the commercial acid by dissolving 65 to 70 








635 

grammes in enough water to make a litre of solution, and then de- 
termining the strength of this solution by a titration with pure 
sodium carbonate, making use of the following memoranda : 

Na 2 C0 3 + H 2 C 2 4 ,2H 2 = Na 2 C 2 4 + C0 2 + 3H 2 

2 )125.7 

62.85 

The decinormal solution will be one-tenth the strength, 6.285. 

Liquor Calcis. — Measure out about 100 cc. of the lime-water, and 
weigh. The following equations, etc. are quantitative expressions 
of the reactions : 

Ca2HO + H 2 C 2 4 ,2H 2 = CaC 2 4 + 4H 2 
2 0)125.7 

6.28=1000 cc. of standard solution. 

Or, CaOH 2 + H 2 C 2 4 ,2H 2 = CaC 2 4 -f 4H 2 

20)56_ 20 )125.7 

28 6.285 = 1000 cc. of standard solution. 

Phenolphthalein is used as an indicator. The official lime-water is to 
contain .14 per cent. Ca(OH) 2 . 

Potassium Permanganate. — The reaction is shown in the following 
equation : K 2 Mn 2 8 + 3H 2 S0 4 -f 5(H 2 C 2 4 ,2H 2 0) = K 2 S0 4 + 2Mn- 
SO 4 +18H 2 O + 10CO 2 . 

K 2 Mn 2 8 and 5(H 2 C 2 4 ,2H 2 0) 
100)315.34 100)628.5 

3.14 6.285 = grammes in 1000 cc. of standard solution. 

The salt satisfies official requirements if it contains 98.7 per cent of 
real potassium permanganate. 

Normal Hydrochloric Acid Solution may be used in some cases, 
instead of sulphuric or oxalic acid. It is so made that 1000 cc. con- 
tain 36.37 grms. of pure HC1. 

Weighing. — In the case of substances which are liable to alter by 
exposure to air it is important that a selected quantity should be 
quickly weighed, rather than selected weights be accurately balanced 
by material, the former operation occupying much the shorter time. 

Salts other than the official may be quantitatively analyzed by the 
volumetric solutions of the Pharmacopoeia, slight modifications of 
manipulation even enabling the processes to be adapted to fresh 
classes of salts. 



QUESTIONS AND EXERCISES. 

Describe the apparatus used in volumetric determination. — 100 cubic 
centimetres of solution of oxalic acid contain 6.3 grammes of the crystal- 
lized salt ; work sums showing what weights of potassium bicarbonate 



636 VOLUMETRIC QUANTITATIVE ANALYSIS. 

and anhydrous sodium carbonate that volume will saturate. Ans. 10 
grammes and 5.3 grammes. — Show what weight of potassium hydrate is 
contained in solution of potash 48.02 grammes of which are saturated by 
50 cc. of the standard solution of sulphuric acid. Ans. 5.83 per cent. — 
Calculate the percentage of calcium hydrate in lime-water, 438 grammes 
of which are neutralized by 20 cc. of the volumetric solution of sulphuric 
acid. Ans. 0.1689. — 8 grammes of a sample of Eochelle salt, after igni- 
tion, etc., require 54.3 cc. of the official sulphuric acid solution for com- 
plete saturation ; work sums showing what is the centesimal proportion 
of real salt present. Ans. 95.7. 



ESTIMATION OF ACIDS. 

In the previous experiments a known amount of an acid has been 
used in determining unknown amounts of alkalies. In those about 
to be described a known amount of an alkali is employed in esti- 
mating unknown amounts of acids. The alkaline salt selected may 
be either a hydrate or a carbonate, but the former is to be preferred ; 
for the carbonic acid set free when a strong acid is added to a car- 
bonate interferes to some extent with the indications of alkalinity, 
acidity, or neutrality afforded by litmus. The alkali most conve- 
nient for use is either potash or soda, a solution of which has prob- 
ably already been made the subject of experiment in operations 
with the standard solution of sulphuric acid. It should be kept in 
a stoppered bottle and exposed to air as little as possible. 



Volumetric Solution of Potash. 

(Potassium Hydrate, KHO = 55.99, say 56.) 

This aqueous solution of potash is most conveniently made of 
such a strength that each 1000 cc. contains one molecular weight in 
grammes of the alkali (KHO = 56). It will be seen from the fol- 
lowing equation that 56 grammes of potash convert 48.91 grammes 
of sulphuric acid into the neutral potassium sulphate : 

H 4 S0 4 + 2KHO K 2 S0 4 + 2H 2 

2)97.82 

48.91 = 1000 cc. of stand, sol. 56 = 1000 cc. of standard solution. 

If pure caustic potash were at hand, it would only be necessary to 
weigh 56 grammes, dissolve this in water, and dilute to 1 litre. 
But pure potash cannot be readily produced. Therefore weigh 
about 60 grammes of commercial caustic potash, and add water to 1 
litre. When dissolved take, say, 14 cc, dilute with more water in a 
flask, add a few drops of tincture of litmus, and titrate with sul- 
phuric-acid solution of known strength. Suppose that the volume 
of standard acid solution required to neutralize the 14 cc. of potash 
solution, the strength of which is to be estimated, has been 15 cc, or 
an equivalent amount of acid solution. of another strength; then, 
how many cc. of potash solution are equivalent to 1000 cc of stand- 



ESTIMATION OF ACIDS. 637 

ard acid solution ? or, what comes to the same thing, how many cc. 
of potash solution contain 66 grammes of real potash (KHO) ? As 
15 cc. standard acid are to 14 cc. potash solution, so are 1000 cc. 
standard acid to x cc. x = 933 cc. of the potash solution contains, 
therefore, 56 grammes of potash. This may either be diluted, every 
933 cc. to 1000 cc, so that it may be standard (1000 cc. = 56 
grammes KHO), or the solution may be used without dilution (933 
cc. = 56 grammes KHO). It has already been mentioned that soda 
nearly always contains carbonate. To remove resulting carbonic 
acid, therefore, gentle heat should be employed toward the close of 
each titration in all the estimations with this solution if litmus is 
used as an indicator of completion of the reaction. There is, how- 
ever, no need to warm if phenolphthalein be used instead of litmus, 
as is ordered in the United States Pharmacopoeia. The following 
substances are officially estimated with this solution. The list 
admits of considerable extension : 

Acetic Acid. — Operate upon about 1 gramme of glacial acid, about 
20 grammes of diluted acid, or about 3 grammes of ordinary acetic 
acid. 

HC 2 H 3 2 + KHO = KC 2 H 3 2 + H 2 

60 56 = 1000 cc. standard solution. 

Acetic Acid, U. S. P., should contain 36 per cent, of real acid 
(HC 2 H 3 2 ) ; Diluted Acetic Acid, U. S. P., 6 per cent. ; Glacial 
Acetic Acid, U. S. P., 99 per cent. 

Citric Acid. — Operate on about 1 gramme. The reaction is ex- 
pressed by the following equation, etc. : 

H 3 C 6 H 5 7 ,H 2 + 3KHO = K 3 C 6 H 5 7 + 4H 2 



3) 210 

70 56 = 1000 cc. standard solution. 

Citric Acid, TJ. S. P., should be pure (= 100 per cent. H 3 C 6 H 5 7 ,- 
H 2 0). 

Hydrochloric Acid. — Operate . on from 1 to 2 grammes of the con- 
centrated acid or on about 4 grammes of the diluted acid. 

HC1 4- KHO = KC1 -f H 2 

36.5 56 = 1000 cc. standard solution. 

Hydrochloric Acid, U. S. P., should contain 31.9 per cent, of real 
acid (HC1), and Diluted Hydrochloric Acid, U. S. P., 10 per cent. ; 
Diluted Hydrobromic Acid, 10 per cent. (HBr). 

Lactic Acid. — Operate on 1.5 to 2 grammes. The reaction is 
expressed by the following equation : 

HC 3 H 5 3 4- KHO == KC 3 H 5 3 + H 2 

90 56 = 1000 cc. of standard solution. 

Lactic Acid, U. S. P., should represent 75 per cent, of absolute lactic 

acid (HC 3 H 5 3 ). 

28 



638 VOLUMETRIC QUANTITATIVE ANALYSIS. 

Nit?*ic Acid. — Operate on from 1 to 2 grammes of concentrated 
or on from 4 to 5 grammes of dilute acid. 

HN0 3 + KHO 3= KNO3 + H 2 

63 56 = grammes in 1000 cc. standard solution. 

Nitric Acid, U. S. P., should contain 68 per cent., and Diluted 
Nitric Acid, U. S. P., 10 per cent, of absolute acid (HN0 3 ). 

Sulphuric Acid. — Operate upon from .5 to 1 gramme of concen- 
trated acid, or from 4 to 5 grammes of either diluted or aromatic 
sulphuric acid. 

H 2 S0 4 -f 2KHO = K 2 S0 4 + H 2 

2)98 2 )112 

49 56 = 1000 cc. standard solution. 

Sulphuric Acid, U. S. P., should contain 92.5 per cent. ; Diluted, 
U. S. P., 10 per cent. ; and Aromatic, U. S. P., 18.5 per cent, of 
absolute acid (H 2 S0 4 ). 

Phosphoric Acid. — Operate upon about 1 to 1.5 grammes of the con- 
centrated acid or from 5 to 6 grammes of the diluted phosphoric acid. 

H 3 P0 4 + 2KHO = K 2 HP0 4 + H 2 
2)97.8 2 )112 

48.9 56 = 1000 cc. standard solution. 

Phosphoric Acid, U. S. P., should contain 85 per cent., and Diluted 
Phosphoric Acid, U. S. P., 10 per cent., of absolute acid (H 3 P0 4 ). 

Hypophosphorous Acid. — Operate upon 6 to 7 grammes of the 
official acid. 

HPH 2 2 + KHO = KPH 2 2 -f- H,0 

65.88 56 == 1000 cc. standard solution. 

Diluted Hypophosphorus Acid, U. S. P., should contain 10 per cent, 
of absolute acid (H 3 P0 2 ). 

Tartaric Acid. — Operate upon about 1 gramme of the acid. The 
following equation, etc. represents the reaction : 

H 2 C 4 H 4 O s + 2NaHO =Na 2 C 4 H 4 6 + H 2 
2 )150 2)80 

75 40 = grammes in 1000 cc. standard solution. 

Tartaric Acid, U. S. P., should contain 100 per cent, of H 2 C 4 H 4 6 . 

Normal Soda Solution may be used instead of the potash. It is 
prepared similarly, making 1000 cc. contain 40 grammes (NaOH). 
^ Notes. — 1. Pure acetates, citrates more especially, tartrates, and 
some other organic salts, have an alkaline action on litmus, but not 
to an important extent. If the potash solution be added to acetic, 
citric, or tartaric acid containing litmus until the liquid is fairly 
blue, the operator will obtain trustworthy results. It is best to use 



ESTIMATION OF ACIDULOUS RADICALS. 639 

phenolphthalein, as recommended in the United States Pharmacopoeia. 
It is produced by reaction of phenol and phthalic anhydride. Its 
tincture yields an intense red color with potash or soda-, hence 
U. S. P. ordering it to be used as an indicator of the termination of 
volumetric reactions ; it is especially useful with organic acids. The 
" Tincture of Phenolphthalein," B. P., is made by dissolving 1 
gramme of phenolphthalein in 500 of proof spirit. 

2. The operations for the quantitative analysis or measurement of 
acids are often collectively spoken of under the name of oxidimetry. 



QUESTIONS AND EXEECISES. 



Calculate the percentage of real acid present in diluted sulphuric acid 
30 grammes of which are neutralized by 84 cc. of the official volumetric 
solution of potash. Ans. 13.72. — Show how much real nitric acid is con- 
tained in a solution 36 grammes of which are saturated by 94 cc. of the 
standard solution of potash. Ans. 16.45 per cent. 



ESTIMATION OF ACIDULOUS RADICALS PRECIPI- 
TATED BY SILVER NITRATE. 

The purity of many salts and the strength of their solutions may 
be determined by this process ; but only eighteen official substances 
(including diluted hydrocyanic acid, other cyanides, and some bro- 
mides and iodides) are quantitatively analyzed by standard solution 
of silver nitrate. 

Standard Solution of Silver Nitrate. 

(Silver Nitrate, AgN0 3 = 169.55, say 170.) 

Dissolve 17 grammes of crystals of pure silver nitrate in 
1 litre of water. 1000 cc. of this solution contain T x o of the 
molecular weight in grammes of silver nitrate. It is therefore 
a decinormal solution. 

If pure dry crystals of silver nitrate are not at disposal, and 
pure dry crystals of sodium chloride are at hand, a solution may be 
made of approximate strength, and then be standardized by means 
of that salt. The method may be thus indicated : 

NaCl + AgN0 3 = AgCl + NaN0 3 
10 )58.5 10)170 

5.85 17.0 = grammes in 1000 cc. standard solution. 

Take rather less than .1 gramme of sodium chloride (NaCl), 
and dissolve in water. The salt (AgCl) precipitated in the reaction 
is an insoluble salt, and the end of its precipitation will serve as a, 
good indication of the completion of the reaction. A better indi- 
cator, however, is a few drops of neutral potassium chromate (which 
previously was well purified by recrystallization). The silver nitrate 



640 VOLUMETRIC QUANTITATIVE ANALYSIS. 

does not act upon the chromate until all the chloride is converted 
into silver chloride, after which a deep red precipitate of silver 
chromate is produced. This indication is extremely delicate, and in 
practice is noticed when the white color due to silver chloride 
changes to yellowish from formation of the first traces of silver 
chromate. Solutions should be cool and not very dilute. The 
titration being accomplished, suppose that .1 gramme of the sodium 
chloride has taken 17 cc. of the silver-nitrate solution of unknown 
strength ; how many cc. of the solution are equivalent to 5.85 of the 
sodium chloride ; that is, how many cc. of solution contain 17 
grammes of silver nitrate ? As .1 gramme of NaCl is to 17 cc, so are 
5.85 NaCl to x cc. = 994 cc. 994 cc. of the solution of silver nitrate 
are equivalent, therefore, to 1000 cc. of official standard solution, 
and contain 17 grammes of the silver nitrate. They may be diluted 
to 1000 cc. if desired. 

Hydrocyanic Acid. — 3 to 4 grammes of diluted acid form a con- 
venient quantity to operate upon. The HON is first converted into 
KCN or NaCN with potash or soda. The following equations, 
etc. explain the reactions ' 

2HCN + 2NaHO = 2NaCN + 2H 2 




2NaCN + AgN0 3 = AgCN,NaCN + NaN0 3 
10)98 1 0)170 

9.8 17.0 = grammes in 1000 cc. of standard solution. 

It is seen that 5.4 grammes of real hydrocyanic acid (HCy) are 
equivalent to 9.8 grammes of sodium cyanide, and represent 17 
grammes of silver nitrate or 1000 cc. of standard solution of silver 
nitrate. 

The sodium cyanide having been obtained, the titration is carried 
on until the salt is converted into the double salt (NaCy,AgCy), 
immediately after which a permanent turbidity occurs,, due to pre- 
cipitation of cyanide of silver, thus : 

AgCy,NaCy + AgN0 3 = 2AgCy + NaN0 3 . 

This turbidity forms a delicate and satisfactory proof of the com- 
pletion of the volumetric reaction. 

There is, however, a difficulty in the conversion of the acid into 
the cyanide (Siebold), to which it is necessary to pay particular 
attention. Tincture of litmus is added to the acid diluted largely 
with water, and the soda poured in. Owing to the strong alkaline 
reaction of the sodium cyanide formed, the mixture becomes blue 
when only a small proportion of the acid has been converted. If, 
then, the titration be conducted until the turbidity appears, only the 
sodium cyanide will be estimated, leaving free hydrocyanic acid still 
unacted upon. Indeed, sodium cyanide may be estimated in presence 



ESTIMATION OF ACIDULOUS RADICALS. 641 

of hydrocyanic acid in this way. Thus the following reaction 
(expressed approximately) might occur : 

NaCy + 4HCy -f AgN0 3 = AgCy + NaN0 3 + 4HCy 

Alkaline. Turbid and acid. 

In this case only one-fifth of the cyanogen originally present 
would be estimated. The mixture would, however, become acid. If 
this acidity be prevented, all difficulty is overcome. The following 
details (Senier) will be found to answer well : To the diluted hydro- 
cyanic acid add soda solution until a strong alkaline reaction is 
shown by the tincture of litmus. Then add the silver solution, drop 
by drop, from the burette, when in most cases the mixture will 
become acid. When it does so, add more soda solution, and repeat 
this process until the final reading, when the solution must be 
alkaline. In this way the addition of too much soda at the com- 
mencement, which would use up silver solution and make the 
reading a trifle too high, is avoided. 

Diluted Hydrocyanic Acid, B. P. and U. S. P., should contain 2 
per cent, of real acid (HCN) — Aqua Laurocerasi, B. P., 0.1 per cent. 

The following is the quantitative test of purity ordered by the 
United States Pharmacopoeia: "Mix in a flask (of the capacity of 
about 100 cc.) 0.27 grm. of hydrocyanic acid (obtained by distilla- 
tion as above directed) with sufficient water and magnesia to make 
an opaque mixture of about 10 cc. Add to this 2 or 3 drops of 
potassium chromate, and then, from a burette, decinormal silver 
nitrate V. S., until a red tint is produced which does not again dis- 
appear by shaking. Each cc. of silver nitrate used indicates 1 per 
cent, of absolute hydrocyanic acid. After ascertaining the strength 
of the distillate, dilute it with distilled water so as to bring it to the 
strength of 2 per cent, of absolute acid. Lastly, test the finished 
product again, when 1.35 grms. of it should require, for complete 
precipitation, 10 cc. of decinormal silver nitrate." 

Potassium Cyanide. — .65 grm., in dilute solution, requires 45 cc. of 
standard decinormal silver nitrate = 90 per cent, of pure salt. 

Ammonium Bromide. — Operate upon .075 to .1 gramme of the 
salt, using potassium chromate (or Bichromate, U. S. P.) as an 
indicator of the close of the reaction : 

NH 4 Br + AgN0 3 = AgBr + NH 4 N0 3 

. 10)97.8 10)170 

9.78 17.0 = 1000 cc. of standard solution. 

Ammonium Bromide, U. S. P., should be of 99 per cent, purity, but 
as the impurity is ammonium chloride, this too will be precipitated 
by the silver nitrate,, and must be calculated in finding the percent- 
age of bromide. 

NH 4 C1 + AgN0 3 = AgCl + NH 4 N0 3 . 

10 )53.5 10)170 

5.35 17.0 = 1000 cc. of standard solution. 



642 VOLUMETRIC QUANTITATIVE ANALYSIS. 

The amount of the salt equivalent to 1000 cc. of standard solution 
is first calculated by simple proportion : Let x represent this ; then 
9.78 — x = y, the excess of standard solution used up by the ammo- 
nium chloride, reckoned in terms of bromide (NH 4 Br) ; and since 
5.35 grammes of NH 4 C1 = 9.78 grammes of NH 4 Br, the excess 
which ammonium chloride can consume is represented by 9.78 — 
5.35 = 4.43 ; therefore, as 4.43 : 5.35 : : y : z = the amount of 
ammonium chloride present in x grammes of the sample taken ; 
lastly, the percentage is calculated by simple proportion : 

As x : 100 : : z : p = percentage. For example : .075 gramme 
of the salt required, 7.8 cc. of standard solution, 

1. 7.8 : 1000 : : .075 : arj 

x = 9.615. 

2. 9.78-9.615 = 2/; 

y = .165. 

3. 4.43 : 5.35 : : .165 : z; 

z = . 19926. 

4. 9.615 : 100 : : .19926 : p ; 

p = 2.072 per cent, of NH 4 C1. 
Potassium Bromide. — Operate upon rather less than .1 gramme, 
and conduct the titration in the same manner as with sodium chlo- 
ride, using potassium chromate as an indicator of the close of the 
reaction. 

KBr + AgN0 3 = AgBr -f KN0 3 

10)119 10 )170 

11.9 17.0 = grammes in 1000 cc. of standard solution. 

The United States Pharmacopoeia requires potassium bromide to 
contain 97 per cent, of the pure salt, and sodium bromide 97.29 per 
cent. 

Remembering that 170 parts of silver nitrate (AgN0 3 = 170) 
decompose 119 of potassium bromide (KBr = 119), while, on the 
one hand, they decompose as little as 74.5 of potassium chloride 
(KC1 = 74.5), and, on the other hand, as much as 166 parts of 
potassium iodide (KI = 166), it will be seen that the quantitative 
operation of the chloride as an impurity may neutralize the quanti- 
tative operation of the iodide. Hence the necessity to test the 
bromide qualitatively as well as quantitatively, and, as regards 
either impurity singly, of fixing maximum as well as minimum 
limits of the action of the volumetric solution of silver nitrate on 
potassium bromide. 

Lithium Bromide. — Operate on about half a gramme. 

LiBr -f AgN0 3 = LiN0 3 + AgBr 




10 )86.8 

grammes in 1000 cc. of standard solution. 

Lithium Bromide, U. S. P., should contain 98 per cent, of the pure salt. 



ESTIMATION OF ACIDULOUS RADICALS. 643 

Calcium Bromide. — Operate on about J a gramme. 
CaBr 2 + 2AgN0 3 == 2AgBr + Ca(N0 3 ) 2 

20 )199.4 20)340 

9.97 17.0 = grammes in 1000 cc. of standard solution. 

The United States Pharmacopoeia requires calcium bromide to con- 
tain 99.7 per cent, of the pure salt. 

Strontium Bromide would be estimated similarly, and the official 
substance should contain 98 per cent, of the pure salt. 
SrBr 2 ,6H 2 + 2AgN0 3 = 2AgBr + Sr(N0 3 ) 2 

20 )354.60 20)340 

17.73 17.0 = grammes in 1000 cc. of standard solution. 

Potassium Iodide. — Operate on about £ a gramme of the sub- 
stance. 

KI + AgN0 3 = Agl + KN0 3 

10 )165.6 1 0)170 

16.56 17 = grammes in 1000 cc. of standard solution. 

The United States Pharmacopoeia requires potassium iodide to con- 
tain 99.5 per cent, of the pure salt. 

The sodium iodide is estimated in the same way by making the 
alterations shown previously, and should contain 98 per cent, of 
the pure salt (Nal). 

The sodium chloride is estimated, as shown on p. 639, and the 
official salt should contain 99.9 per cent, of pure NaCl. 

Potassium Iodide may be volumetrically estimated by a decinor- 
mal solution of mercuric chloride, the termination of the operation 
being indicated by the commencement of the formation of a red 
precipitate : 

(1) 4KI + HgCl 2 = 2KC1 + HgI 2 ,2KI (soluble). 

(2) HgI 2 ,2KI -f HgCl 2 = 2KC1 + 2HgI 2 (insoluble). 

The author of this process, M. Personne, stated (in 1875) that 
neither chlorides, bromides, nor carbonates interfere. Carles dis- 
solves the iodide in spirit of wine of 17J per cent. ; as much excess 
of water may decompose the double iodides. 

Ferrous Iodide — Messrs. Naylor and Hooper (in 1881) demon- 
strated that Personne' s solution is applicable to ferrous iodide, even 
in the state of syrup : 

(1) 2FeI 2 + HgCl 2 = FeCl 2 + FeI 2 ,HgI 2 (soluble). 

(2) FeI 2 ,HgI 2 + HgCl 2 = FeCl 2 -f 2HgI 2 (insoluble). 

The use of mercuric chloride for estimating the strength of syrup 
of iodide of iron was first suggested by E. Smith in 1859. The 
process was improved by T. and H. Smith in 1860. 

Zinc Chloride, Bromide, and Iodide. — Operate on about n a 
gramme of the substance, as described in the case of Calcium, etc. 
The official salts should contain, respectively, 99.84 per cent., 99.95 



644 VOLUMETRIC QUANTITATIVE ANALYSIS. 

per cent., and 98.62 per cent, of the pure salts. The equations will 
explain any difficulty that may occur : 

ZnCl 2 + 2AgN0 3 = 2AgCl + Zn(N0 3 ) 2 

20 )135.8 20 )340 

6.79 17.0 = grammes in 1000 cc. of standard solution. 

ZnBr 2 + 2AgN0 3 = 2AgBr + Zn(N0 3 ) 2 

2 0)224.6 2 0)340 

11.23 17.0 = grammes in 1000 cc. of standard solution. 

Znl 2 + 2AgN0 3 = 2AgI 2 + Zn(N0 3 ) 2 
20 )318.2 2 0)340 

15.91 17.0 = grammes in 1000 cc. of standard solution. 

Syrup of Hydriodic Acid. — Operate upon 10 to 15 grammes. The 
reaction which occurs is as follows : 

HI + AgN0 3 = Agl + HN0 3 
10 )127.6 10 )170 

12.76 17.0 = grammes in 1000 cc. of standard solution. 

The close of the reaction is shown by the cessation of the formation 
of silver iodide, the nitric acid liberated rendering potassium chro- 
mate inadmissible as an indicator. 

Syrupus Acidi Hydriodici, U. S. P., should contain 1 per cent, of 
anhydrous hydriodic acid (HI). 

Syrup of Ferrous Iodide. — Operate upon 1 to 2 grammes of the 
syrup until no further precipitate is formed : 

Fel 2 + 2AgNO, = 2AgI + ' Fe(N0 3 ) 2 

. 2 0)309.1 2 0)340 

15.455 17.0 = grammes in 1000 cc. of standard solution. 

Syrupus Ferri Iodidi, U. S. P., should contain 10 per cent, of iodide 
of iron (Fel 2 ). 

Spirit of Wine (Spiritus Rectificatus, B. P.) may contain traces 
of amylic alcohol and aldehyde ; these may be detected by silver 
nitrate, which is reduced by them to the metallic state. Any quan- 
tity beyond a mere trace of such bodies renders spirit of wine too 
impure for use in medicine. " 4 fluidounces with 30 grain-measures 
(about 2 cc.) of the volumetric solution of silver nitrate, exposed for 
twenty-four hours to bright light, and then decanted from the black 
powder which has formed, undergoes no further change when again 
exposed to light with more of the test." — B. P. "If 20 cc. of alco- 
hol be shaken in a clean glass-stoppered vial with 1 cc. of silver 
nitrate, the mixture should not become more than faintly opalescent, 
or acquire more than a faint brownish tint when standing during six 
hours in diffused daylight (limit of organic impurities, amylic alco- 
hol, etc.)."— U. S. P. ^ 



ESTIMATION OF SUBSTANCES READILY OXIDIZED. 645 

QUESTIONS AND EXERCISES. 

Explain the volumetric method of estimating the strength of aqueous 
solutions of hydrocyanic acid. — Work a sum showing how much silver 
nitrate will indicate, by the official volumetric process, the presence of 1 
part of real hydrocyanic acid. Ans. 3.148 parts. 



ESTIMATION OF SUBSTANCES READILY OXIDIZED. 

Any deoxidizer — that is, any substance which quickly absorbs a 
definite amount of oxygen or is suspceptible of any equivalent 
action — may be quantitatively tested by ascertaining how much 
of an oxidizing agent of known power must be added to a given 
quantity before complete oxidation is effected. The oxidizing agents 
employed for this purpose in the United States Pharmacopoeia are 
iodine, the red potassium chromate, and potassium permanganate. 
Iodine acts indirectly by taking hydrogen from water and liberating 
oxygen ; the red potassium chromate, directly by the facility with 
which it yields three-sevenths of its oxygen — as indicated by the 
equations and statements given on p. 651 ; potasssium permangan- 
ate, by affording five-eighths of its oxygen in presence of acid, 

2K 2 Mn 2 8 + 6II 2 S0 4 = 2K 2 S0 4 + 4MnSO, 4- 6H 2 + 50 2 . 

Standard Solution of Iodine. 
(Iodine, I = 126.53.) 

The Pharmacopoeia allows 127 to be taken as the atomic weight 
of iodine for rough purposes, but recommends 126.53 as the datum 
for accurate work. This fact should be borne in mind in the fol- 
lowing simplified operations and calculations : 

If pure iodine be not at hand, it may be prepared by mixing the 
commercial article with about a fourth of its weight of potassium 
iodide and subliming. Sublimation may be effected by gently 
warming the mixture in a beaker the mouth of which is closed by a 
funnel ; the iodine vapor condenses on the funnel, while fixed im- 
purities are left behind, and any chlorine which the iodine may con- 
tain is absorbed by the potassium iodide, an equivalent quantity of 
iodine being liberated. Small quantities may be similarly treated 
between two watch-glasses, placed edge to edge. Any trace of 
moisture in the resublimed iodine is removed by exposure for a few 
hours under a glass shade near a vessel containing oil of vitriol. 

Place 12.7 grammes of pure iodine and about 18 grammes of pure 
potassium iodide (an aqueous solution of which is the best solvent 
of iodine ; the salt plays no other part in these operations) in a litre 
flask; add a little .water and agitate until the iodine is dissolved ; 
dilute to 1 litre. 

The following substances are officially estimated by this standard 
decinormal volumetric iodine solution : 

Sulphurous Acid.— Operate on about .5 of a gramme of the acid, 
and dilute with water as usual. If the sulphurous acid be diluted 
to a less degree than .04 or .05 per cent., there will be some risk of 
28- 




646 VOLUMETKIC QUANTITATIVE ANALYSIS. 

the sulphuric acid formed being again reduced to sulphurous acid, 
with liberation of iodine. In delicate experiments the distilled 
water used for dilution should previously be freed from air by boil- 
ing, to prevent the small amount of oxidizing action which dissolved 
air would exert. The solution of iodine is then added until a slight 
permanent brown tint is produced, showing the presence of free 
iodine. A better indicator of the termination of the reaction is 
starch mucilage, which gives a blue color with the slightest trace of 
free iodine. 

The following equations, etc. show the reaction that takes place : 

+ I 2 . — 2HI + H 2 S0 4 
20)254 

12.7 = grms. in 1000 cc. of stand, sol. 

H 2 0,S0 2 + H 2 + I 2 = 2HI + H 2 S0 4 
20)64 20)254 

3.2 12.7 = grmsi in 1000 cc. of stand, sol. 

The official (U. S. P.) sulphurous acid should contain 64 per cent, 
of sulphurous anhydride (S0 2 ). 

Arsenic. — About .1 of a gramme of solid arsenic, accurately 
weighed, should be dissolved in the usual quantity of water, heated 
to boiling, by aid of about .5 of a gramme of sodium bicarbonate. 
The arsenous acid is only partly, if at all, converted into sodium 
arsenite or arsenate ; but the iodine reaction occurs more readily in 
an alkaline solution. When the liquid is quite cold, mucilage of 
starch is added, and the iodine solution allowed to flow in until, after 
well stirring, a permanent blue color is produced. The official 
Liquor Potassi Arsenitis, U. S. P., already containing some potas- 
sium carbonate, requires somewhat less sodium bicarbonate. 10 
grammes is a convenient quantity to operate upon. To this should 
be added the usual quantity of water and about .3 of a gramme of 
sodium bicarbonate. After boiling and cooling the titration is 
carried on as before. About 10 grammes of the official Liquor Acidi 
Arsenosi, U. S. P., is also a convenient quantity to operate upon. 
This quantity requires about .6 pf a gramme of sodium bicarbonate. 
The usual quantity of water is added and the titration performed 
as before. The following equation exhibits the reaction : 

As 2 3 + 5H 2 + 2I 2 = 4HI + 2H 3 As0 4 

40)198 40)508 

4.95 12.7 = grammes in 1000 cc. standard sol. 

The United States Pharmacopoeia requires both the above solutions 
of arsenic to contain 1 per cent, of As 2 3 , and the arsenous acid 
98.8 per cent, of As 2 3 . 

In the foregoing operation, if ebullition be continued longer than 
is necessary for the solution of the arsenic, more monocarbonate of 
sodium may be formed than will be reconverted into bicarbonate by 



ESTIMATION OF SUBSTANCES READILY OXIDIZED. 647 

the liberated carbonic acid ; loss of iodine will then ensue. E. J. 
Woolley has shown that borax may be usefully employed in the 
place of the sodium bicarbonate. 

Antimony also passes from lower -to higher active quantivalence 
under the influence of nascent oxygen, iodine, or an equivalent 
acidulous radical. The following equation illustrates the reaction 
with tartar emetic and iodine. The student should make several 
determinations on, say, 20 cc. of a solution of 2 grammes of pure 
crystals of tartar emetic in 200 cc. of water. To the 20 cc. add about 
an equal amount of strong solution of sodium bicarbonate, a couple 
of cc. of starch mucilage, and then the iodine solution, until, after 
stirring, the blue color is fairly persistent. The whole operation 
should be quickly conducted, or a precipitate of antimonious hydrate 
will be formed, and it is only when in solution that the antimony is 
properly attacked. This process is by Mohr. It has been tested by 
Fresenius and in the Research Laboratory of the Pharmaceutical 
Society, and is trustworthy. 

(KSbOC 4 H 4 6 ) 2 ,H 2 + 2I 2 + 3H 2 = 4HI + 2KHC 4 H 4 6 + 2HSbO s 

4 0)6621 " 4 0)508 

16.56 12.7 = grammes in 1000 cc. of standard sol. 

The official Tartar Emetic, U. S. P. should be absolutely pure (100 
per cent.). 

Hyposulphite of Sodium.— About .4 of a gramme is a convenient 
quantity to employ. It is dissolved in water, starch mucilage added, 
and the iodine solution slowly run in, the whole being frequently 
stirred, until a permanent blue color is produced. 

In the previous reactions iodine has acted as an indirect oxidizing 
agent by uniting with the hydrogen and thus liberating the oxygen 
of water. In the present case it unites with an analogue of hydro- 
gen — namely, sodium — a new salt (tetrathionate of sodium) being 
also produced, thus : 

2(Na 2 S 2 3 ,5H 2 0) + I 2 = 2NaI + Na 2 S 4 6 




20)496 

24.8 12.7 = grammes in 1000 cc. of standard solution. 

The United States Pharmacopoeia requires " Sodium Hyposulphite," 
now generally termed sodium thiosulphate, to contain 98.1 per cent 
of the crystalline salt. 

Sodium Sulphite. — About .7 grammes is a convenient quantity to 
take, using starch mucilage as an indicator, as before. The reaction 
as below occurs : 

Na 2 S0 3 ,7H 2 Q + I 2 = 2NaI + H 2 S0 4 + 6H 2 
20 )251.6 20)254 

12.58 12.7 = grammes in 1000 cc. of standard solution. 

Sodium sulphite should contain 96 per cent, of the pure crystalline 
salt (Na 2 S0 3r 7H 2 0). 



648 VOLUMETRIC QUANTITATIVE ANALYSIS. 

Sodium Bisulphite. — Operate upon .2 to .3 gramme, as before : 
NaHS0 3 + I 2 + H 2 = Nal + H 2 S0 4 + HI 

20 )103.9 20)254 

5.19 12.7 = grammes in 1000 cc. of standard solution. 

The United States Pharmacopoeia requires bisulphite of sodium to 
contain 90 per cent, of the pure salt (NaHS0 3 ). 



QUESTIONS AND EXERCISES. 

Give equations illustrative of the reactions on which the use of a 
standard volumetric solution of iodine is based. — From what point of 
view is iodine an oxidizing agent ? — What reagent indicates the termina- 
tion of the reaction between deoxidizing substances and moist iodine?— 
How much sulphurous acid gas will cause the absorption of 2.54 parts of 
iodine in the volumetric reaction ? Ans. 0.64. — What quantity of iodine 
will be required, under appropriate conditions, to oxidize 5 parts of 
arsenic? Ans. 12.828. — Find by calculation the amount of sodium hypo- 
sulphite which will react with 13 parts of iodine in volumetric analysis. 
Ans. 25.386. 



Volumetric Solution of Red Potassium Chromate. 
(Red Potassium Chromate, K 2 Cr 2 7 = 293.78.) 

One molecule of red potassium chromate in presence of an acid, 
under favorable circumstances, yields four atoms of oxygen to the 
hydrogen of the acid, leaving three available either for direct oxida- 
tion or for combination with the six atoms of hydrogen of more acid, 
an equivalent proportion of acidulous radical being liberated for any 
required purpose. One-sixth, therefore, of the molecular weight of 
red chromate, taken in grammes (293.78 -r6 = 48.963), and dis- 
solved in 1000 cc, would form a normal solution (for that is the 
amount which is equivalent to one atomic weight, in grammes, 1 .0, 
of hydrogen ; see p. 626), while one-sixtieth (4.8963) in 1 litre would 
form the official decinormal solution. For all practical purposes 294 
may be taken as the molecular weight = 4.9 grammes per litre. 

When used as a volumetric agent the red chromate always yields 
the whole of its oxygen to the hydrogen of the accompanying acid, 
a corresponding quantity of acidulous radical being set free — four- 
sevenths of this radical immediately combining with the potassium 
and chromium of the red chromate, three-sevenths becoming avail- 
able. Ferrous salts may thus be converted into ferric with sufficient 
rapidity and exactitude to admit of the estimation of an unknown 
quantity of iron by a known quantity of the red chromate. As one 
atom of any liberated bivalent acidulous radical will convert two 
molecules of ferrous salt into one of ferric, one molecule of red chro- 
mate causes six of ferrous to become three of ferric, as shown in the 
following equation : 

K 2 Cr0 4 ,Cr0 3 + 7H 2 S0 4 -f 6FeS0 4 = K 2 S0 4 ,Cr 2 3S0 4 + 
7H 2 + 3(Fe 2 3S0 4 ). 






ESTIMATION OF SUBSTANCES READILY OXIDIZED. 649 

The volumetric solution is made by dissolving 14.75 grammes 
(^ of a molecular weight in grammes) of red potassium chromate 
in water, and diluting to 1 litre. It is used in determining the 
strength of the ferrous preparations. It is known that the whole 
of the ferrous has been converted to ferric salt when a small drop 
of the liquid placed in contact with a drop of a fresh and very dilute 
solution of potassium ferricyanide on a white plate ceases to strike 
a blue color. 

If the red chromate employed in making this standard solution 
is not known to be pure and dry, the strength of the solution may 
be checked by dissolving a small accurately weighed piece of piano- 
forte wire (0.4 or 0.5) in diluted sulphuric acid in a small flask, 
warming, and then running in the solution of red chromate until 
conversion is effected. 

The reactions which take place may be thus expressed : 
6Fe + 6H 2 S0 4 = 6FeS0 4 -f 6H 2 

60)336 60)912 

5.6 15.2 

6FeS0 4 + K 2 Cr 2 7 + 7H 2 S0 4 = K 2 S0 4 ,Cr 2 3S0 4 + 7H 2 + 3(Fe 2 3S0 4 ) 

60)912 60)295 

15.2 4.9 — grammes in 1000 ce. of standard solution. 

It is evident that 16.8 grammes of iron are equivalent in the 
reactions to 14.75 of red chromate or 1000 cc. of standard solution 
of the chromate. Now suppose that 0.5 of a gramme of pianoforte 
wire has been employed, and the quantity of solution of red chromate 
of unknown strength used has been 28 cc. How many cc. of this 
solution contains 1.475 of red chromate? — that is, how many cc. 
must be required to oxidize ferrous salt containing 16.8 of iron? 
As .5 of iron is to 28 cc. sol., so are 16.8 of iron to x cc. sol. = 941 
cc. Of the supposed solution, then, 941 cc. would contain 14.75 
grammes of red chromate, and would be equivalent to 1000 cc. of 
standard solution. It might be employed without being diluted, 
or, better, be diluted to official standard strength. 

For standardizing the solution of red chromate, instead of iron 
wire the light-green crystals of the double ferrous ammonium sul- 
phate (FeS0 4 ,(NH 4 ) 2 S0 4 ,6H 2 = 392) may be employed, for it is a 
very stable salt. 

Special care should be taken in all these estimations of substances 
readily oxidized to avoid atmospheric oxidation. Flasks may usually 
be loosely corked, or corked closely with a gas exit-tube passing just 
beneath a little mercury, and in all cases the estimation should be 
performed quickly.. When standardizing with iron wire any slight 
oxidation may be remedied by a fragment of zinc, the last portions 
of which must be removed or dissolved before the titration is com- 
menced. 

The " Decinormal Potassium Dichromate Volumetric Solution," 
U. S. P., is made from 4.89 (say 4.9) grammes of K 2 Cr 2 7 dissolved 
in 1000 cc. of water. 



650 VOLUMETRIC QUANTITATIVE ANALYSIS. 

When used with phenolphthalein as indicator to neutralize alkalies, 
the volumetric solution of potassium dichromate is decinormal when 
it contains 14.689 grms. in 1 litre. It is then the exact equivalent 
of any decinormal acid, corresponding to the amounts of alkalies 
quoted, for instance, under Decinormal Oxalic Acid. 

When used as an oxidizing agent to convert ferrous into ferric 
salts or to liberate iodine from potassium iodide, the solution just 
mentioned (containing 14.689 grms. in 1 litre) has the effect of a 
(tD volumetric solution, and a solution of one-third of this strength, 
containing 4.896 grms. in 1 litre, has the value of a decinormal solu- 
tion, and is the equivalent of equal volumes of decinormal potassium 
permanganate, or, in the case of iodide liberated from potassium 
iodide, it is the equivalent of equal volumes of decinormal sodium 
hyposulphite. — U. S. P. 

The ferrous salt in the following substances is estimated officially 
by this solution : 

Saccharated Ferrous Carbonate. — Operate upon 1 to 2 grammes. 
Dissolve in excess of diluted sulphuric or hydrochloric acid. Sul- 
phuric acid is preferable in most cases, because ferrous sulphate 
absorbs oxygen much less readily than ferrous chloride. The reac- 
tion that occurs is shown in the following equation, the ferrous 
carbonate being converted into ferric sulphate : 

6FeC0 3 + 13H 2 S0 4 + K 2 Cr 2 7 = 
60)696 60)295 

11.6 4.90 = grammes in 1000 cc. of standard solution. 

K 2 S0 4 Cr 2 3S0 4 + 3(Fe 2 3S0 4 ) + 13H 2 + 6C0 2 

The official (U. S. P.) strength in iron is 15 per cent. Trade samples 
yield from 20 to 30, and sometimes 35 per cent., according to the 
care with which oxidation has been prevented. The theoretical per- 
centage obtainable from the ingredients is 45.5, the quantity that 
would be present if the compounds were anhydrous and unoxidized — 
conditions never obtained in practice. Howie has suggested that as 
hydrochloric acid is known to so rapidly convert ordinary sugar 
into inverted sugar as to lender it easily attacked by chromic acid, 
while phosphoric acid very slowly affects sugar, the latter acid 
instead of the former should be employed in dissolving the sacchar- 
ated ferrous carbonate for volumetric analysis. Another mode of 
eliminating the action of sugar is to char with sulphuric acid before 
analyzing. 

Ferrous Sulphate. — Take about 1 to 2 grammes of the substance 
and titrate in the usual way. The equations are given on p. 614. 
Both the official ferrous sulphates are required to be absolutely pure 
(100 per cent.). 

Ferrous Arsenate.— Operate upon 1 to 2 grammes ; proceed as 
with the carbonate. The reaction that occurs is shown in the fol- 
lowing equation, the ferrous arsenate being converted into ferric 
arsenate : 



ESTIMATION OF SUBSTANCES READILY OXIDIZED. 651 

2(Fe // 3 2As0 4 ) + 7H 2 S0 4 + K 2 Cr 2 0, = 
60)892 6 0)295 

14.9 4.90 = grammes in 1000 cc. stand. solution. 

K 2 S0 4 ,Cr 2 3S0 4 + Fe /// 2 3S0 4 + 2(Fe'" 2 2As0 4 ) + 7H 2 

Arsenate of Iron, B. P., is supposed to contain about 10 per cent, of 
ferrous arsenate. The compound is more nearly a ferric than a 
ferrous arsenate. 

Ferrous Phosphate. — Operate upon 1 to 2 grammes. Proceed as 
with the carbonate. The following equation indicates the reaction, 
the ferrous phosphate being converted into ferric phosphate : 

2(Fe' 3 2P0 4 + 7H 2 S0 4 + K 2 Cr 2 7 = 
60)716 60)295 

1.1.94 4.90 = grammes in 1000 cc. of standard solution. 

K 2 S0 4 ,Cr 2 3S0 4 + Fe'" 8 3S0 4 + 2(Fe /// 2 2P0 4 ) + 7H 2 

The official (B. P.) requirement is about one-third of its weight of 
anhydrous ferrous phosphate, or 47 per cent of Fe 3 (P0 4 ) 2 ,8H 2 0. 

Phosphate of Iron, U. S. P., is Ferric Phosphate, and therefore 
cannot be estimated by this solution. 

Magnetic Iron Oxide. — Operate upon 1 or 2 grammes, and pro- 
ceed as with arsenate or phosphate. The reaction may thus be 
shown : 

6Fe 3 4 + 31H 2 S0 4 + K 2 Cr 2 7 = 

60 )1392 " 6 0)295 

23.2 4.90 = grammes in 1000 cc. of standard solution. 

K 2 S0 4 ,Cr 2 3S0 4 + 9(Fe 2 3S0 4 ) + 31H 2 
Or, 

6(Fe 2 3 ,FeO) + 31H 2 S0 4 -f K 2 Cr 2 7 = 

60)432 60)295 

7*.2 4.90 = grammes in 1000 cc. of stand, solution. 

K 2 S0 4 ,Cr 2 3S0 4 + 9(Fe 2 3S0 4 ) + 31H 2 

Absolutely pure magnetic iron oxide contains 31 per cent, of 
ferrous oxide. Oxidation occurs, however, during manufacture, as 
in the case of the ferrous salts just described. 

Note. — The use of this volumetric solution in quantitative analy- 
sis admits of great extension. The student should at least employ 
it in the case of a few iron ores. 



QUESTIONS AND EXERCISES. 

Write equations explanatory of the oxidizing power of red potassium 
chromate. — 100 cub. cent, of an aqueous solution of red potassium chro- 



652 VOLUMETRIC QUANTITATIVE ANALYSIS. 

mate contain ^u °f the molecular weight of the salt in grammes ; with 
what weight of metallic iron, dissolved in hydrochloric acid, will this 
volume react? Ans. 1.68 gramme. — If 8.34 grammes of impure crystal- 
lized ferrous sulphate, dissolved in acidulated water, require 93 cc. of the 
standard solution of chromate for complete conversion into ferric salt, 
what percentage of ferrous sulphate is present ? Ans. 93. — Work a sum 
showing how much red potassium chromate is required for the conversion 
of 10 parts of ferrous sulphate into ferric salt. Ans. 1.768. — Show what 
quantity of pure ferrous carbonate is indicated by 1.475 part of red 
chromate as applied in volumetric analysis.' Ans. 3.48. — Prove what 
amount of official saccharated ferrous carbonate is equivalent to .7375 
part of red chromate in the volumetric reaction. Ans. 4.7. 



Standard Solution of Potassium Permanganate* 

(Potassium Permanganate, K 2 Mn 2 8 = 315.34.) 

Dissolve about 3.5 grammes of potassium permanganate crystals in 
distilled water. Boil the solution in a large basin for a quarter of 
an hour. Allow to stand for a couple of days, and then pour off 
the clear solution and make up to 1000 cc. This solution must be 
now standardized by the following reaction : 

10FeSO 4 + 8H 2 S0 4 = 

315.34 
2MnS0 4 + K 2 S0 4 + 5Fe 2 (S0 4 ) 3 +8H 2 

Weigh out carefully about 1 gramme of polished pianoforte wire •, 
place this in a 250 cc. flask with about 70 cc. of dilute sulphuric 
acid ; then add about a gramme of sodium carbonate. Close the 
flask with a Bunsen valve (a Bunsen valve is easily made by making 
a longitudinal slit about ^ of an inch long in a short piece of india- 
rubber tubing, closing one end with a piece of glass rod, and placing 
the other on the tube passing through the cork ; gases can escape 
by the slit thus formed, but cannot re-enter), and heat on the sand- 
bath until all the wire is dissolved. Allow the flask to cool, and 
only when perfectly cold remove the cork and fill up to the mark 
with water. Titrate 25 cc. of this solution with the permanganate 
solution. The strength can be easily calculated from the equation 

* Potassium permanganate affords five-eighths of its oxygen in pres- 
ence of acid. Thus: 

K 2 Mn 2 8 + 3H 2 S0 4 = K2SO4 + 2MnS0 4 + 3H 2 + O5 ; 
the five liberated atomic weights of oxygen (O5) at once performing 
chemical work equivalent to the oxidation of ten atomic weights of 
hydrogen (H10). Hence, one-tenth (31.534) of the atomic weight of 
potassium permanganate (K 2 Mn 2 08 = 315.34), taken in grammes (31.534), 
dissolved in water, and made up to 1 litre (1000 cc), would form a normal 
solution, while a solution of one-tenth of this strength (3.1534 grammes 
in 1000 cc), the " Decinormal Potassium Permanganate Volumetric Solu- 
tion," U. S. P., K 2 MnO*4 and K 2 Mn20s, are the probable formulae of potas- 
sium manganate and permanganate, but the latter is sometimes written 
KMnO*. 



ESTIMATION OF SUBSTANCES READILY OXIDIZED. 653 

given above. Care must be taken to deduct 0.4 per cent, from the 
weight of iron wire taken, for impurities. AVhen the strength has 
been found — that is, how many cc. of the permanganate solution 
contains 3.15 grms. of potassium permanganate — make this number 
of cc. up to 1000 by adding water. 

The United States calls this " Decinormal Potassium Perman- 
ganate/' 

The following substances are officially estimated with this 
solution : 

Hydrogen Dioxide Solution. — Take about 2 cc. and place in a 
beaker, dilute and add permanganate until a faint pink color is 
produced. The equation will explain the reaction : 

5H 2 2 + K 2 Mn 2 8 + 3H 2 S0 4 = K 2 S0 4 + 2MnS0 4 + 8H 2 + 50 2 
100 )169.5 10 0)315.3 

1.69 3.15 = grammes in 1000 cc. of standard solution. 

The United States Pharmacopoeia requires Aqua Hydrogenii Dioxidi 
to contain 3 per cent, of H 2 2 . 

Barium Dioxide. — Operate on about .5 of a gramme ; the reaction 
is similar to hydrogen dioxide : 

5Ba0 2 + K 2 Mn 2 8 -f 3H 2 S0 4 = 
10 0)844.1 100 (315.3 

8.44 3.15= grammes in 1000 cc. of standard solution. 

K 2 S0 4 + 2MnS0 4 + 3H 2 + 50 2 + 5BaO 

Barium dioxide should contain 80 per cent, of pure Ba0 2 . 

Ferrous Carbonate and Sulphate. — Operate on about 1 to 2 
grammes. The two equations will show the action with the car- 
bonate, and the second one for the sulphate. The action of the 
sulphuric acid on the ferrous carbonate is to produce ferrous sul- 
phate, which then gets oxidized to ferric sulphate. 11.59 grammes 
of the carbonate are equivalent to 3.15 grms. of potassium perman- 
ganate. 

10FeCO 3 4- 10H 2 SO 4 = 10FeSO 4 + 10CO 2 + 10H 2 O 

10 0)1159 1519 

11.59 
Then 

10FeSO 4 + 8H 2 S0 4 + K 2 Mn 2 8 = 
100 )1519 10 0)315.3 

15.19 3.15 = grammes in 1000 cc. of stand, solution. 

5Fe 2 (S0 4 ) 3 + K 2 S0 4 + 2MnS0 4 -f- 8H 2 

The United States Pharmacopoeia requires the saccharated ferrous 
carbonate to contain 15 per cent, of FeC0 3 ; the crystalline and the 
granulated ferrous sulphate should both be pure — 100 per cent. 



654 VOLUMETRIC QUANTITATIVE ANALYSIS. 

Reduced Iron. — Use about 1 to 1.5 grammes, and place the "re- 
duced iron into a glass-stoppered bottle ; add 50 cc. of mercuric 
chloride, and heat the bottle, well stoppered, during one hour on a 
water-bath, frequently agitating. Then allow it to cool, dilute the 
contents with water to the volume of 100 cc, and filter. To 10 cc. 
of the filtrate, contained in a glass-stoppered bottle (having a capacity 
of about 100 cc), add 10 cc. of diluted sulphuric acid, and subsequently 
decinormal potassium permanganate, until a permanent red color is 
produced. The number of cc of the volumetric solution required, 
when multiplied by 10, will indicate the percentage of metallic 
iron" (U. S. P.), and should contain 80 per cent, of iron as metal. 

lOFe + 10H 2 SO 4 = 10FeSO 4 + 10H 2 

10 0)559 1519 

5.59 
10FeSO 4 + 8H 2 S0 4 -f K 2 Mn 2 8 = 

100 )1519 100 )315.3 

15.19 3.15 = grammes in 1000 cc. of standard solution. 

5Fe 2 (S0 4 ) 3 + K 2 S0 4 + 2MnS0 4 + 8H 2 

" To confirm the assay, decolorize the liquid by a few drops of 
alcohol, then add 1 grm. of potassium iodide, and digest for half an 
hour at a temperature of 40° C. (104° F.). The cooled solution, 
mixed with a few drops of starch, should require not less than 
8 cc. of decinormal sodium hyposulphite to discharge the blue or 
greenish color( each cc. of the volumetric solution indicating 10 per 
cent, of metallic iron)." — U. S. P. 

Hypophosphorous Acid is officially estimated with standard potas- 
sium-permanganate solution. Take about .7 gramme of the diluted 
acid and add water ; proceed to titrate in the usual way until a pink 
color is just produced after shaking. 

The following equation will explain the reaction : 

5H 3 P0 2 + 2K 2 Mn 2 8 4- 6H 2 S0 4 = 
200 )329.4 20 0)630.6 

1.647 3.15 = grammes in 1000 cc. of standard solution. 

5H 3 P0 4 4- 2K 2 S0 4 + 4MnS0 4 4 6H 2 

The United States Pharmacopoeia required Acidum HypophospJiorum 
Dilutum to contain 10 per cent, of pure acid. 

Calcium, Ferric, Potassium, and Sodium Hypophospliites. — Ope- 
rate on from .1 to .2 grammes and proceed as above. The following 
equations correspond with the official data : 

5Ca(H 2 P0 2 ) 2 + 4K 2 Mn 2 8 + 17H 2 S0 4 = 
400 )848.5 400)1 261.2 

2. 1210 3.15 = grammes in 1000 cc. of standard solution. 

5CaS0 4 4- 10H 3 PO 4 -f 4K 2 S0 4 + 8MnS0 4 4" 12H 2 



ESTIMATION OF SUBSTANCES READILY DEOXIDIZED. 655 

5Fe 2 (H 2 P0 2 ) 6 + 12K 2 Mn 2 8 + 51H 2 S0 4 = 

120 0)2505.2 1200 )3783.6 

2.088 3.15 = grammes in 1000 cc. of standard solution. 

5Fe 2 (S0 4 ) 3 + 12K 2 SO, + 24MnS0 4 + 36H 2 + 30H 3 PO 4 

10KH 2 PO 2 + 4K 2 Mn 2 8 + 17H 2 S0 4 = 
400)1039.1 400)1261.2 

2.597 3.15 = grammes in 1000 cc. of standard solution. 

9K 2 S0 4 + 8MnS0 4 -f- 10H 3 PO 4 + 12H 2 
10NaH 2 PO 2 ,H 2 O + 4K 2 Mn 2 8 + 17H 2 S0 4 = 

400)1058.4 400 )1261.2 

2.646 3.15 ^grammes in 1000 cc. of standard solution. 

5Na 2 SO i + 10H 3 PO 4 -f 4K 2 S0 4 4- 8MnS0 4 4- 1 3H 2 

The official requirements are — calcium salt to contain 99.68 per 
cent, of the pure salt; ferric salt, 98.1 percent. ; potassium salt, 98.7 
per cent. ; sodium salt, 97.9 per cent. 

Centinormal Potassium Permanganate is a solution, 1000 cc. 
of which contain .315 gramme of permanganate. It is useful for 
estimating small quantities of iron, etc. 



ESTIMATION OF SUBSTANCES READILY DEOXIDIZED. 

Any substance which quickly yields a definite amount of oxygen 
may be quantitatively tested by ascertaining how much of a deoxi- 
dizing agent of known power must be added to a given quantity 
before complete deoxidation is effected. The chief compounds which 
may be used for this absorption of oxygen (deoxidizers or reducing 
agents, as they are commonly termed) are sodium hyposulphite, 
sulphurous acid, ferrous sulphate,* oxalic acid, arsenous acid. The 
first-named is officially employed ; it is only used in the estimation 
of free iodine, and, indirectly, of chlorine and chlorinated com- 
pounds. Iodine and chlorine are regarded as oxidizing agents, 
because their great affinity for hydrogen enables them to become 
powerful indirect oxidizers in presence of water. 

Standard Solution of Hyposulphite of Sodium. 

(Crystallized Hyposulphite of Sodium, Na 2 S 2 3 5H 2 = 247.64, or, 
roughly, 248.) 

Dissolve about 27 grammes of sodium hyposulphide in a litre or 
less of water. Fill a burette with this solution, and allow it "to flow 
into a beaker containing, say, 15 cc. of the volumetric solution of 

* Five grains of permanganate of potassium dissolved in water require 
for decoloration a solution of 44 grains of granulated sulphate of iron 
acidulated with 2 fluidrachms of diluted sulphuric acid. 



656 VOLUMETRIC QUANTITATIVE ANALYSIS. 

iodine until the brown color of the iodine is just discharged — or, 
starch being added, until the blue iodide of starch is decolorized. 
(The latter affords the more delicate indication.) When iodine and 
sodium hyposulphite react, two atoms of iodine remove two of sodium 
from two molecules of the hyposulphite, sodium tetrathionate being 
formed, thus : 

I 2 + 2(Na 2 S 2 3 ,5H 2 0) = 2NaI -f Na 2 S 4 6 + 10H 2 O 

20 )126.53 20)495.2 

15.6531 = grins, of iod. 24.764 = grms. of hypo, in 1000 cc. 

in 1000 cc. 

Now suppose the number of cc. required to fully attack the 15 cc. 
of standard iodine were 14 cc, how many cc. of this hyposulphite 
solution would be equivalent to 1000 cc. of standard iodine solu- 
tion ? In other words, how many cc. would contain 24.8 grammes of 
hyposulphite? As 15 cc. iodine solution are to 14 cc. hyposulph. 
solution, so are 1000 iodine solution to x hyposulph. solution = 933 
cc. Therefore 933 cc. of this solution of hyposulphite would con- 
tain 24.8 grammes of the salt, and be equivalent to 1000 cc. of the 
official standard solution. The 933 cc. would be diluted to 1000 cc. 
or be used without dilution. In either case its strength would, as 
usual, be recorded on the label. The following substances are 
estimated officially by means of this solution : 

Chlorine Solution. — About 10 grammes are operated upon. Ex- 
cess of potassium iodide is added — that is, to 10 grammes of solution 
of chlorine about J a gramme of iodide. An amount of iodine is set 
free by the chlorine exactly in proportion to their atomic weights. 
The titration is then conducted as already described. The following 
equations show the reactions : 

CI + 2KI = I 2 + 2KC1 

20 )70.74 20)253 

3.537 12.65 

I 2 + 2(Na 2 S 2 3 ,5H 2 0) = 2NaI + Na 2 S 4 6 -f 10H 2 O 

20)253 20 )495.2 

12.65 24.764 = grammes in 1000 cc. of standard solution. 

It is evident, then, that 1000 cc. of standard solution of sodium 
hyposulphite, or a corresponding quantity of a solution of different 
strength, is equivalent to 3.37 grammes of chlorine gas. Chlorine 
solution of the United States Pharmacopoeia contains 0.4 per cent, 
of chlorine. 

Iodine. — Solid iodine is dissolved in solution of potassium iodide 
and titrated as already described. About .2 of a gramme is a con- 
venient quantity to employ. 1000 cc. of standard hyposulphite solu- 
tion is equivalent, as seen in the equation, to 12.65 of iodine. The 
United States Pharmacopoeia requires "iodine" to contain 98.85 per 
cent, of real iodine. It is assumed in this operation that the iodine 
has been shown by qualitative analysis to be free from chlorine and 



ESTIMATION OF SUBSTANCES READILY DEOXIDIZED. 657 

bromine. These elements resemble iodine in reacting upon sodium 
hyposulphite, hence would reckon as iodine in a volumetric assay. 

Chlorinated Lime. — Operate on from .1 to .2 of a gramme. Dis- 
solve in the usual quantity of water, and add excess of potassium 
iodide and diluted hydrochloric acid. .1 to .2 of a gramme of 
chlorinated lime would require .4 to .8 of a gramme of potassium 
iodide. The following equations show the reactions : 

CaOCl 2 + 2HCl = CaCl 2 +H 2 + C1 2 : 
or, CaOCl 2 + H 2 S0 4 = CaS0 4 + H 2 + Cl 2 . 

The chlorine thus set free liberates an equivalent amount of iodine, 
and this is titrated as before. (See the equations for solution of 
chlorine, p. 656.) This chlorine, liberated from chlorinated lime by 
acids, is its available chlorine for indirect oxidizing action. It 
should correspond (U. S. P.) to 35 per cent, of chlorine. 

Solution of Chlorinated Soda. — About 2 grammes are mixed with 
the usual quantity of water and about 1 gramme of potassium iodide, 
and excess of acid added. The available chlorine is estimated as in 
the case of chlorinated lime. The reaction by which the chlorine 
is evolved is familiar : 

NaCl,NaOCl + 2HC1 = 2NaCl + H 2 + Cl 2 . 

The action of the liberated chlorine on the potassium iodide and 
the iodine on the hyposulphite solution has been described under 
"Solution of Chlorine." The official (U. S. P.) requirement is 
about 2.6 per cent, of available chlorine. 

Compound Solution of Iodine. — Process as before, using 1 or 2 
grammes ; the reaction has already been given. The requirements 
of the United States Pharmacopoeia are 5 per cent, of free iodine. 

Tincture of Iodine. — Use about 1 gramme. It will contain 7 per 
cent, of free iodine in 100 cc. when of official strength. 



QUESTIONS AND EXERCISES. 

For what purpose is the official volumetric solution of sodium hypo- 
sulphite used ? — On what reaction is based the quantitative employment 
of sodium hyposulphite ? — How much sodium hyposulphite is required to 
show the presence of 10 parts of iodine 1—Ans. 19,527.— Calculate the 
amount of chlorine 4.96 parts of sodium hyposulphite are equivalent to 
in volumetric analysis. Ans. 71. — Describe the operations included in 
the estimation of the strength of bleaching-powders. — By what reagent 
is the complete absorption of free iodine by sodium hyposulphite in- 
dicated ? 



Other volumetric solutions are official. 

Decinormal Sodium Chloride Volumetric Solution. 
(Sodium Chloride, NaCl = 58.37.) 
Dissolve 5.84 grammes of pure sodium chloride* in 1000 cc. of 
* Pure sodium chloride may be prepared by passing dry hydrochloric 



658 VOLUMETEIC QUANTITATIVE ANALYSIS. 

water. This solution may be used as it is or standardized with 
decinormal silver nitrate. 

NaCl + AgN0 3 = AgCl -f NaN0 3 

10 )58.37 1 0)169.55 

5.837 16.955 = grammes in 1000 cc. of stand, solution. 

The salts to be estimated with this standard solution of sodium 
chloride are the three official nitrates. The above equation will 
explain the reactions, Operate on about .5 to 1 gramme. Argentic 
nitrate should contain 99.97 per cent, of the pure salt, the fused 
nitrate 95 per cent., and the mitigated caustic 95 per cent., to fulfil 
the requirements of the United States Pharmacopoeia. 

"Decinormal Bromine Volumetric Solution 1 ' (Kappeschaars 
Solution) contains 7.976 grammes of bromine in 1000 cc. It is 
only used to test Acidum Carbolicum, U. S. P., which should con- 
tain 96 per cent, of pure phenol. 

"Decinormal Mercuric Potassium Iodide Volumetric Solution" 
(Mayer's Solution) contains 39.2 grms. of a mixture of mercuric 
iodide and potassium iodide, in the proportion of one molecular 
weight to two. 

"Decinormal Potassium Sulphocyanate Volumetric Solution" 
(Volhard's Solution) contains 9.699 grms. of KSCN in 1000 cc. 



QUESTIONS, WITH ANSWEES FOE VEEIFICATION. 

Work sums showing how much potassium bicarbonate is contained in 
an eight-ounce bottle of medicine, 7 fluidrachms of which are saturated 
by 2h grains of crystallized oxalic acid. Ans. 36.3 grains. — A sample of 
soda-ash is said to contain 78 per cent, of pure anhydrous sodium carbon- 
ate : if the statement be true, how much of the official volumetric solu- 
tion of oxalic acid will saturate 5 grammes of the specimen ? Ans. 73.6. 
— 2.69 grammes of common brown sulphuric acid are saturated by 
43.5 cubic centimetres of the official volumetric solution of soda; 
how much acid of 96.8 per cent, is present? Ans. The 2.69 contain 
2.2. — 4 grammes of 1J litres of concentrated hydrocyanic acid are 
equivalent to 89 cubic centimetres of volumetric solution of silver nitrate 
of official strength ; to what volume must the bulk of the acid be diluted 
for the production of acid of pharmacopoeial strength ? Ans. 9 litres. — 
3.18 grammes of a powder containing arsenic require for complete reac- 
tion 84 cubic centimetres of a volumetric solution of iodine, which is 
1.43 per cent, weaker than the standard solution of the United States 
Pharmacopoeia ; what percentage of pure arsenic is contained in the 
powder ? Ans. 12.86. — How much pure metal is present in a sample of 
iron 1.68 grammes of which, dissolved in diluted sulphuric acid, are exactly 
attacked by 95.7 cubic centimetres of an official volumetric solution of 
red potassium chromate which is .6 per cent, too strong ? 

acid gas into a saturated solution of common salt ; separate the crystals 
which fall, and heat them in a porcelain basin until they are perfectly 
neutral ; that is, until all the HC1 gas has been driven off. 



ESTIMATION OF POTASSIUM. 659 



GRAVIMETRIC QUANTITATIVE ANALYSIS. 

(For preliminary remarks on the general principles of gravimetric 
analysis and the relation of gravimetric and volumetric analyses to 
each other see pp. 591 and 592.) 

ESTIMATION OF METALS. 

POTASSIUM. 

Outline of the Process. — This element is usually estimated in the 
form of double chloride of potassium and platinum. Qualitative 
analysis having proved the presence of potassium and other radicals 
in a substance, a small quantity of the material is accurately weighed, 
dissolved, and the other elements removed by appropriate reagents : 
the precipitates are well washed, in order that no trace of the potas- 
sium salt shall be lost, the resulting liquid concentrated over a 
water-bath (to avoid loss that would occur mechanically during 
ebullition), hydrochloric acid added if necessary, solution of plat- 
inum perchloride poured in, and evaporation continued to dryness : 
excess of the perchloride is then dissolved out by adding to the 
dried residue spirit of wine containing half its bulk of ether (a 
liquid in which the double chloride is insoluble) ; the mixture is 
carefully poured on to a tared and dried filter, washed with the 
spirit till every trace of free platinum perchloride is removed, and 
the whole dried and weighed ; from the resulting amount the pro- 
portion of potassium or equivalent quantity of a salt of potassium is 
ascertained by calculation. 

Note. — From this short description it will be seen, first, that the 
chemistry of quantitative analysis is the same as that of qualitative ; 
and secondly, that the principle of gravimetric is the same as that 
of volumetric quantitative analysis : the combining proportions of 
substances being known, unknown quantities of elements may be 
ascertained by calculation from known quantities of their com- 
pounds. 

Apparatus. — In addition to a delicate balance and weights 
and the common utensils, a few special instruments are used in 
quantitative manipulation ; some of these may be prepared 
before proceeding with the estimation of potassium. 

Filtering-paper may be of the kind known as " Swedish," the 
texture of which is of the requisite degree of closeness and its 
ash small in amount. A large number of circular pieces of 
one size, six to eight centimetres in diameter, should be cut 
ready for use. In delicate experiments, where a precipitate on 
a filter has to be ignited and the paper subsequently burnt, the 
weight of the ash of the filter must be deducted from the 
weight of the residue. The ash is estimated after burning ten 
or twenty of the cut filters. These are folded into a small 



660 



GRAVIMETRIC QUANTITATIVE ANALYSIS. 



compass, a portion of a piece of platinum wire twisted a few 
times round the packet, so as to form a cage, the whole held 
by the free end of the wire over a weighed porcelain crucible 
placed in the centre of a sheet of glazed paper, the bundle 
ignited by a spirit-lamp or smokeless gas flame, the flame 
allowed to impinge against the charred mass till it falls into the 
crucible below, any stray fragments on the sheet carefully 
shaken into the crucible, the latter placed over a flame till car- 
bon has all burnt off, and nothing but ash remains ; the whole 
cooled, weighed, and the weight of the crucible deducted ; the 
weight of the residue, divided by the number of pieces used, 
gives the average amount of ash in each filter. 



Fig. 75. 



Fig. 76. 





A Pair of Weighing-tubes. Clamped Watch-glasses for Weighing. 

A pair of weighing-tubes (Fig. 75), for holding dried filters 
during operations at the balance, may be made from two test- 
tubes, one fitting closely within the other. About five centi- 
metres of the closed end of the outer and seven of the inner 
are cut off by leading a crack round the tube with a pencil of 
incandescent charcoal, and the sharp edges fused in the blow- 
pipe flame. A filter, after drying, is quickly folded and placed 
in the narrower tube, the mouth of which is then closed by the 
wider tube. This prevents reabsorption of moisture from the 
air. A pair of watch-glasses, having accurately ground edges 
and clamped as shown in Fig. 76, also forms a convenient 
arrangement for weighing filters, etc. 

The 



Fig 77. 



bottle (Fig. 77), holding the spirit of wine and 
ether, is a common flask through the cork of 
which a short straight tube passes. The outer 
end of the tube should be sufliciently narrowed 
to enable it to deliver a very fine stream of the 
liquid. The flask being inverted, the warmth 
of the hand expands the air and vapor to a suf- 
ficient extent to force out the liquid. 

The ordinary washing-bottle for quantita- 
tive operations should be formed of a flask in 
which water may be boiled, fitted up as usual. 
( Vide p. 109.) 

A water-oven is the best form of drying apparatus. ^ It is a small 
square copper vessel, jacketed on five sides and having a door on 




ESTIMATION OF POTASSIUM. 661 

the sixth ; water is poured into the space between the inner and 
outer casing, and the whole placed over a gas-lamp or other source 
of heat, moist air and steam escaping by appropriate apertures. 
Desiccation at higher temperatures than the boiling-point of water 
may be practised by using oil or paraffin instead of water, inserting 
a thermometer in the fat. The apparatus may be purchased of any 
maker of chemical instruments. 

Pure distilled water must be used in all quantitative determina- 
tions. 

Note — In practising the operations of quantitative analysis, experi- 
ments should at first be conducted on definite salts of known compo- 
sition, for the accuracy of results may then be tested by calculation. 

Estimation of Potassium in the Form of Double Potassium 
and Platinum Chloride. — Select two or three crystals of pure 
potassium nitrate, powder them in a clean mortar, dry the pow- 
der by gently heating in a porcelain crucible over a flame for a 
few seconds, place about a couple of decigrammes (0.2 grm.) 
of the powder in a counterpoised watch-glass, accurately weigh 
the selected quantity, transfer to a small dish, letting water 
from a wash-bottle flow over the watch-glass and run into the 
dish ; warm the dish till the nitrate is dissolved, acidulate with 
hydrochloric acid, add excess of aqueous solution of platinum 
perchloride (a quantity containing about 0.4 of solid salt), evap- 
orate to dryness over a vapor-bath. While evaporation is going 
on place a filter and the weighing-tubes in the water-oven, ex- 
posing them to a temperature of 100° C. for about half an hour ; 
fold the filter and insert it in the tubes, place them on a plate 
under a glass shade, and when cold accurately note their weight. 
Arrange the weighed filter in a funnel over a beaker. Transfer 
the dried and cooled platinum salt from the dish to the filter 
by moistening the residue with the mixture of alcohol and 
ether, and, when the salt is loosened, pouring the contents of 
the dish into the paper cone. Any salt still adhering may be 
freed by the finger, which, together with the dish, should be 
washed in the stream of spirit, the rinsings at once flowing 
into the filter. The filtrate should have a yellowish-brown 
color, due to the excess of platinum perchloride. If it is color- 
less, an insufficient amount of perchloride has been added, and 
the whole operation must be repeated. The washed precipitate 
and filter are finally dried in the water-oven, folded and placed 
in the weighing-tubes, the drying and weighing when cold 
being repeated until the whole ceases to alter, the final weight 
being noted. 

Desiccators. — Highly-dried substances are very hygroscopic; hence 
before being weighed should be cooled under a bell-jar which also 
encloses a vessel containing sulphuric acid or calcium chloride — a 
29 



662 GKAVIMETRIC QUANTITATIVE ANALYSIS. 

desiccator. (If filters are not freed from all traces of acid by thor- 
ough washing, the paper will be brittle when dry, falling to pieces 
on being folded.) 

Analytical memoranda may have the following form : 

Watch-glass and substance 

Watch-glass , 

Substance . 

Weighing-tubes, filter, and Pt. salt . . 

Weighing-tubes and filter 

PtCL,2KCl . " 



l 4?" 



The calculations are simple 



As | _ 484 g [ is equivalent to \ _ ^^ \ 



the weight of 
so -l double chloride \- is equivalent to x. 
I obtained ) 

x will be the amount of pure potassium nitrate in the quantity 
of substance operated on. x should in the present instance be 
identical with the weight of substance taken, because, for edu- 
cational purposes, pure nitre is under examination. Only after 
analyses of pure substances have yielded the operator results 
practically identical with those by calculation can analyses of 
substances of unknown degree of purity be undertaken with 
confidence. A table of atomic weights, from which to find 
molecular weights, is given in the Appendix. CI = 35.5, or, 
more exactly, 35.4. 

Platinum residues should be preserved, and the metal recovered 
from them from time to time. (Vide p. 249.) 

Hot alcohol sometimes reduces platinum perchloride, the metal 
being thrown out of solution in a finely-divided form, known as 
platinum black; only aqueous solutions, therefore, of the salt should 
be used where heat is employed. Hence, also, »in washing out 
excess of platinum perchloride from the double platinum and potas- 
sium chloride by spirit the application of heat should be avoided. 

Effervescing Potash-water (Liquor Potassa? Effervescens, B. P.) is 
most easily estimated volumetrically (p. 634). Any adulteration 
by an equivalent amount of sodium bicarbonate would, however, by 
that process be undetected ; hence the Pharmacopoeia directs that 
" 5 fluidounces, evaporated to one-fifth, and 12 grains of tartaric 
acid added, yield a crystalline precipitate which when dried weighs 
not less than 12 grains." 5 fluidounces of this preparation should 
contain 7.5 grains of bicarbonate, convertible into 14.1 grains of 
acid potassium tartrate by 11 .25 grains of tartaric acid. The method 
is somewhat rough, but quite efficient for " potash-water " containing 
nothing but bicarbonate of alkali-metals. 






ESTIMATION OF SODIUM AND AMMONIUM. 663 

Proportional Weights of Equivalent Quantities of Potassium and 
its Salts. 

Metal K 2 78 

Oxide (" Potash ") K 2 94 

Hydrate ("Caustic Potash ") . 2KHO 112 

Carbonate (anhydrous) . . . K 2 C0 3 138 

Carbonate (crystalline) . . . K 2 CO s + 16%Aq . .164.285 

Bicarbonate 2KHC0 3 200 

Nitrate 2KN0 3 202 

Platinum salt PtCl 4 ,2KCl 484.8 

SODIUM. 

Sodium is usually estimated as sulphate. Accurately weigh 
a porcelain crucible and lid ; place within about .3 of pure 
rock-salt and again weigh, making a memorandum of the 
weights in a note-book. Add rather more strong sulphuric 
acid than may be considered sufficient to convert the chloride 
into acid sodium sulphate. Heat the crucible gradually, the 
flame being first directed against the side of the crucible to 
avoid violent ebullition, until fumes of acid cease to be evolved, 
toward the end of the operation dropping in one or two frag- 
ments of ammonium carbonate to facilitate complete expulsion 
of all excess of acid. When cold weigh the crucible and con- 
tents. The weight of the crucible having been deducted, the 
amount of sulphate obtained should be the exact equivalent 
of the quantity of sodium chloride employed. 

2NaCl + H 2 S0 4 = Na 2 S0 4 + 2CH1 
116.8 142 

Proportional Weights of Equivalent Quantities of Sodium and its 

Salts. 

Metal Na 2 46 

Oxide ("Soda") Na 2 62 

Hydrate ("Caustic Soda") . 2NaHO 80 

Carbonate (anhydrous) . . . Na 2 C0 3 106 

Carbonate (crystals) .... Na 2 CO 3 ,10H 2 O . . 286 

Bicarbonate 2NaHC0 3 .... 168 

Chloride 2NaCl 116.8 

Sulphate (anhydrous) . . . Na 2 S0 4 142 

Sulphate (crystals) .... Na 2 SO 4 ,10H 2 O . . 322 

AMMONIUM. 

Salts of ammonium are, for purposes of quantitative anal- 
ysis, generally converted into the double ammonium and plat- 
inum chloride (PtCl 4 2NH 4 Cl), the details of manipulation being 



664 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

the same as those observed in the case of potassium (p. 661). 
About 0.15 grm. of pure, white, dry ammonium may be taken 
for experiment. 

Composition of the Platinum Salt. 



Pt . . . . 

Cl 6 . . . . 

a.:::; 


. 194.4 
. 35.4x6 . 
. 14.0X2 . 
1.0X8 . 

. 336 

. 53.4 X 2 . 


In 1 molec. wt. 

. . 194.4 . . 
. . 212.4 . . 

. . 28 . . 
8 . . 


In 100 parts. 

. 43.903 
. 47.967 
, 6.324 
. 1.806 


or, PtCl 4 . . . 
2NH 4 C1 . . 


442.8 

In 1 molec. wt. 

. . 336 . . 

. . 106.8 . . 


100.00 

In 100 parts. 

. 75.88 
. 24.12 



442.8 100.00 

The proportion of nitrogen, ammonium, or ammonium chlor- 
ide in the double chloride may also be ascertained from the 
weight of platinum left on igniting the double chloride ; indeed, 
this operation must be performed if any variety of ammonium 
other than the ordinary hydrogen ammonium may be present. 
The heat must be applied slowly or platinum will be mechan- 
ically carried off with the gaseous products of decomposition. 

Proportional Weights of Equivalent Quantities of Ammoniacal 
Compounds. 

Ammonia (gas) 2NH 3 34 

Ammonium (NH 4 ) 2 ? 36 

Ammonium chloride .... 2NH 4 C1 106.8 

Platinum salt PtCl 4 ,2NH 4 Cl .... 442.8 

"Carbonate of ammonium'" . (NgH^CA)"^ 3X2. 104.7 
Ammonium sulphate .... (NH 4 ) 2 S0 4 132 

BARIUM. 

Barium is estimated in the form of anhydrous barium sul- 
phate (BaS0 4 ), Ba = 136.8. 

Process. — Dissolve 0.3 or 0.4 of pure crystallized and dried 
barium chloride or nitrate in about J a litre of water in a 
beaker, heating to incipient ebullition, and slightly acidulating 
with hydrochloric or nitric acid. Add diluted sulphuric acid 
(prepared some days previously, so that lead sulphate may 
have deposited) so long as a precipitate forms, keep the mix- 
ture hot for some time, set aside for half an hour, pass the 
supernatant liquid through a filter, gently boil the residue twice 
or thrice with acidulated water ; finally, collect the precipitate 
on the filter, removing adherent particles from the beaker by 
the finger and cleansing by a stream of hot water from the 
wash-bottle. The precipitate must be washed with hot water 



ESTIMATION OF CALCIUM. 665 

until the filtrate ceases to turn litmus-paper red or give any 
cloudiness when tested with barium chloride. The filter and 
barium sulphate, having thoroughly drained, are dried in a 
warm place, commonly by supporting the funnel in an inverted 
bottomless beaker over a sand-bath or hot plate. The barium 
sulphate is now removed from the filter, heated to drive off 
every trace of moisture, and weighed. This is accomplished 
by placing a weighed porcelain crucible (and cover) on a sheet 
of glazed paper, holding the filter over it, and carefully trans- 
ferring the precipitate ; the sides of the filter are then gently 
rubbed together and detached powder dropped into the crucible, 
the paper folded, encased in two or three coils of one end of a 
platinum wire, and burnt over the crucible, ash and any par- 
ticles on the sheet of paper dropped into the barium sulphate, 
the open crucible exposed over a flame till its contents are quite 
white, covered, cooled, and weighed. 

Formulae. Molecular 

weights. 

Barium chloride BaCl 2 ,2H 2 .... 243.6 

Barium nitrate Ba^NOg 260.8 

Barium sulphate BaS0 4 232.8 

Composition of Barium Sulphate. 

In 1 In 100 

molec. wt. parts. 

Ba . . . : . 136.8 .... 136.8 58.77 

S 32 .... 32 13.73 

4 ..... . 16 X 4 . . . 64 27.50 

232.8 100.00 

In the first four or five educational experiments it is not 
essential to take filter-ash into account. Mistakes of manipula- 
tion due to inexperience may cause far greater errors. 

CALCIUM. 

Calcium is usually thrown out of solution in the form of 
oxalate, the precipitate ignited, and the resulting carbonate 
weighed. 

Process. — Dissolve 0.3 or 0.4 of dried colorless crystals of 
calc-spar in about a third of a litre of water acidulated with 
hydrochloric acid, heat the solution to near the boiling-point, 
add excess of solution of ammonium oxalate, then ammonia 
until, after stirring, the liquid smells strongly ammoniacal ; set 
aside in a warm place for twelve hours. Carefully pour off the 
supernatant liquid, passing it through a filter ; add . hot water 
to the precipitate, set aside for half an hour, again decant, and, 
after once more washing, transfer the precipitate to the filter, 



666 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

allowing all contained fluid to pass through before a fresh por- 
tion is added. Wash the precipitate with hot water, avoiding 
a rapid stream or the precipitate may be driven through the 
pores of the paper. Dry, transfer to a weighed crucible, and 
incinerate, as described for barium sulphate, and slowly heat 
the precipitate till the bottom of the crucible is just visibly 
red when seen in the dark. As soon as the residue is white or 
only faintly gray remove the lamp, cool, and weigh. 

The resulting calcium carbonate should have the same weight 
as the calc-spar from which it was obtained. If loss has oc- 
curred, carbonic acid gas has probably escaped. In that case 
moisten the residue with water, and after a few minutes test 
the liquid with red litmus- or turmeric-paper ; if an alkaline 
reaction is noticed, it is due to the presence of caustic lime. 
Add a small lump of ammonium carbonate, evaporate to dry- 
ness over a water-bath, and again ignite, this time being care- 
ful not to go beyond the prescribed temperature. The treat- 
ment may, if necessary, be repeated. 

Proportional Weights of Equivalent Quantities of Calcium and its 

Salts. 

Metal . . -. . Ca , 40 

Oxide (quicklime) CaO 56 

Hydrate (slaked lime) . . . Ca2HO 74 

Carbonate CaC0 3 . . . , . . . .100 

Sulphate (anhydrous) . . . CaS0 4 136 

Sulphate (crystalline or 

precipitated) CaS0 4 ,2H,0 . . . .172 

Chloride CaCl 2 1 10.8 

Phosphate (of bones) . . . (Ca 3 2P0 4 ) -r- 3 . . .103.3 

MAGNESIUM. 

Process 1. — The light or heavy magnesium carbonate of phar- 
macy may be estimated by heating a weighed quantity to red- 
ness in a porcelain crucible. If it has the composition indi- 
cated by the formula given in the British Pharmacopoeia 
(3MgC0 3 ,Mg2HO,4H 2 0), it will yield 42 per cent, of mag- 
nesia (MgO). According to that work, the purity of even 
magnesium sulphate (MgS0 4 ,7H 2 0) may be determined by 
boiling a weighed quantity with excess of sodium carbonate, 
collecting the precipitate, washing, drying, igniting, and weigh- 
ing the resulting magnesia (MgO). The crystallized sulphate 
should afford 16.26 percent, of oxide. The official solution of 
magnesium carbonate in carbonic-acid water {Liquor Magnesii 
Carbonatis, B. P.) should yield about 4 grains of pure magne- 
sium oxide per fluidounce. 



ESTIMATION OF ZINC AND MANGANESE. 667 

Process 2. — The general form in which magnesium is precip- 
itated is as ammonium and magnesium phosphate (MgNH 4 P0 4 ,- 
6H 2 0) ; this, by heat, is converted into magnesium pyrophos- 
phate (Mg 2 P 2 7 ). Accurately weigh a small quantity (0.4 to 
0.5) of pure dry crystals of magnesium sulphate, dissolve in 
200 to 300 cubic centimetres of cold water in a beaker, add 
ammonium chloride, ammonia, and sodium or ammonium phos- 
phate, agitate with a glass rod (without touching the sides of 
the vessel, or crystals will firmly adhere to the rubbed portions), 
and set aside for twelve hours. Collect on a filter, wash the 
precipitate with water containing a tenth of its volume of the 
strongest solution of ammonia until the filtrate ceases to give 
a precipitate with an acidulated solution of silver nitrate. Dry, 
transfer to a crucible, burn the filter in the usual way, heat 
slowly to redness, cool, and weigh. 

Proportional Weights of Equivalent Quantities of Magnesium 
Salts. 

Pyrophosphate . . Mg 2 P 2 7 222 

Sulphate .... 2(MgS0 4 ,7H 2 0) 492 

Oxide 2(MgO) 80 

Official carbonate . (3MgC0 3 ,Mg2IIO,4H 2 0) -4-2 .191 

ZINC. 

Zinc is usually estimated as oxide (ZnO), occasionally as 
sulphide (ZnS), Zn = 64.9. 

Process. — Dissolve a weighed quantity (0.5 to 0.6) of zinc 
sulphate in about % a litre of water in a beaker, heat to near 
the boiling-point, add sodium carbonate in slight excess, boil, 
set aside for a short time ; pass the supernatant liquid through 
a filter, gently boil the precipitate with more water, again 
decant ; repeat these operations two or three times ; collect the 
precipitate on the filter, wash, dry, transfer to a crucible, incin- 
erate, ignite, cool, and weigh. 286.9 (= molec. weight) of sul- 
phate should yield 80.9 (= molec. weight) of oxide. 

MANGANESE. 

To ascertain its value for evolving chlorine from hydrochloric 
acid, a weighed quantity of finely-powdered black manganese 
oxide is heated in a small flask with pure hydrochloric acid 
(contained in an inner tube, as for " oxalates " and " carbon- 
ates," p. 683), and the resulting chlorine conveyed into a 
U-tube containing solution of potassium iodide. (See Fig. 78.) 
The amount of iodine thus freed is estimated by the volumet- 



668 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

ric solution of sodium hyposulphite. 126.6 of iodine indicate 
35.4 of chlorine. 



Fig. 78. 




(Manganese may also be estimated by the reaction and ap- 
paratus described under " Oxalates, p. 684.) 

ALUMINIUM. 

Aluminium is always precipitated as hydrate (Al 2 6HO) and 
weighed as oxide (A1 2 3 ). 

Process. — Dissolve about 2 grammes of pure dry ammonium- 
alum in | a litre of water, heat the solution, add ammonium 
chloride and a slight excess of ammonia, boil gently till the 
odor of ammonia has nearly disappeared, set aside for the 
hydrate to deposit, pass the supernatant liquid through a filter, 
wash the precipitate three or four times by decantation, trans- 
fer to the filter, finish the washing, dry, burn the filter, ignite 
in a covered crucible, cool, and weigh. 

A1 2 3S0 4 K 2 S0 4 ,24H 2 : 948 

A1 2 3S0 4 ,(NHJ 2 S0 4 ,24H 2 . . . 906 

A1 2 3 m 102 

Per cent, of A1 2 3 yielded by ammonium-alum . 11.26 



QUESTIONS AND EXERCISES. 

Give details of the manipulations observed in gravi metrically esti- 
mating salts of potassium or of ammonium. — What quantity of sodium 
chloride is contained in a sample of rock-salt, 0.351 of a gramme of which 
yields 0.426 of sodium sulphate? Ans. 99.83 per cent. — To what amount 
of the ammonium-alum is 0.888 of a gramme of the double platinum 
and ammonium chloride equivalent? — Ans. 1.817 grammes. — Find the 
weight of barium sulphate obtainable from 0.522 of nitrate? Ans. 0.466. 
— Describe the usual method by which salts of calcium are estimated. — 
By what quantitative process may the official salts of magnesium be 
analyzed? — Calculate the proportion of pure ziuc sulphate in a sample of 



ESTIMATION OF IRON. 669 

crystals 0.574 of which yield 0.161 of oxide. Ans. 99.4 per cent. — Ascer- 
tain the weight of alumina (AI2O3) which should be obtained from 1.812 
grammes of ammonium-alum. 



IRON. 

Iron and its salts are gravimetrically estimated in the form 
of ferric oxide (Fe 2 3 ). 

Compounds containing organic acidulous radicals are simply- 
incinerated and the resulting oxide weighed. Thus 1 gramme 
of the official citrate of iron and ammonium (Ferri et Ammonii 
Citras, B. P.), incinerated, with exposure to air, leaves not less 
than .27 of ferric oxide. A small quantity of the salt is 
weighed in a tared covered porcelain crucible, flame cautiously 
applied until vapors cease to be evolved, the lid then removed, 
the crucible slightly inclined and exposed to a red heat until 
all carbonaceous matter has disappeared. The residual ferric, 
oxide is then weighed. Potassium and iron tartrate (Ferrum 
Tartaratum, B. P.) is treated in the same manner, except that 
the ash must be washed and again heated before weighing, in 
order to remove potassium carbonate produced during incinera- 
tion ; 5 grammes should yield about 1.5 grammes of ferric oxide. 

From other compounds of iron, soluble in water or acid, the 
metal is precipitated in the form of hydrate (Fe 2 6HO) by solu- 
tion of ammonia, and converted into oxide (Fe 2 3 ) by ignition. 
Dissolve a piece (about 0.2) of the purest iron obtainable 
(piano wire), accurately weighed, in water acidulated with 
hydrochloric acid ; add a few drops of nitric acid, and gently 
boil ; pour in excess of ammonia, stir, set aside till the ferric 
hydrate has deposited, pass the supernatant liquid through a 
filter, treat the precipitate three or four times with boiling 
water ; transfer to the filter, wash till the filtrate yields no trace 
of chlorine (for ammonium chloride will decompose ignited fer- 
ric oxide, with volatilization of ferric chloride) ; dry, and ignite 
as usual, and weigh. Iron in the official solutions (Liquor 
Ferri Acetatis, Liquor Ferri Nitratis, and Liquor Ferri Tersul- 
phatis) is estimated by this general process. 

The proportion of metallic iron in a mixture of iron and 
oxides of iron may be determined by digestion in a strong solu- 
tion of iodine and potassium iodide, which attacks the metal 
only. The reduced iron of pharmacy (Ferrum Reductum, U. S. 
P.) is in good condition so long as it contains, as shown by this 
method, half its weight of free metal. 

Another Method. — Reduced iron is converted into ferrous 
chloride by a hot, strong solution of corrosive sublimate, while 
29* 



670 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

the oxides are not affected. The filtrate may be treated gravi- 
metrically or volumetrically (Wilner). 

Proportional Weights of Equivalent Quantities of Iron and its 

Salts. 

Metal Fe 2 112 

Ferric oxide .... . . . Fe 2 3 160 

Ferric hydrate Fe 2 6HO 214 

Ferric chloride .... Fe z Cl 6 324.4 

Ferric sulphate Fe 2 3S0 4 400 

Ferrous sulphate .... 2(FeS0 4 ,7H 2 0) .... 556 

ARSENUM. 

Arsenic (As 2 3 ) is usually estimated volumetrically (vide 
p. 651), and sometimes arsenates also (vide p. 646), but th.Q 
latter are best precipitated as a lead salt ; an " aqueous solution 
of 12.4 grains of anhydrous sodium arsenate, acidulated with 
acetic acid, requires not less than 34 grains. of lead acetate for 
complete precipitation." With certain precautions arsenum 
may be precipitated and weighed as sulphide (As 2 S 3 ). 

Process 1. — The pure white arsenic in lump (about 0.2) is 
dissolved in a flask in a small quantity of water containing 
sodium or potassium bicarbonate, the .liquid being heated. A 
slight excess of hydrochloric acid is then added, and sul- 
phuretted hydrogen gas passed through the solution so long as 
a precipitate falls, the mouth of the flask being stopped by a 
plug of cotton-wool (to prevent undue access of air and con- 
sequent decomposition of the gas, resulting in precipitation of 
sulphur). The mixture is warmed in the flask, and carbonic 
acid gas passed through it until the odor of sulphuretted 
hydrogen has nearly disappeared ; the precipitate is collected 
on a tared filter, washed as quickly as possible with hot water 
containing a little sulphuretted hydrogen, dried in a water- 
oven, and weighed. 198 parts of arsenic should yield 246 of 
arsenum sulphide. 

Process 2. — The arsenum must be present in the arsenic con- 
dition. If the operator is not certain that this is the case, the 
solution must be warmed with a little hydrochloric acid and a 
few grains of potassium chlorate added until a distinct odor of 
chlorous vapor is evolved, which is then allowed to escape by 
continued application of heat. To the solution thus obtained 
ammonia, which must produce no turbidity, is added in excess, 
and then magnesia mixture. (See under " Phosphates," p. 684.) 
The solution is set aside for twenty-four or forty-eight hours. 
The precipitate is collected on a filter and washed with as little 
ammonia-water (1 to 3) as possible until the filtrate ceases to 



ESTIMATION OF ANTIMONY AND COPPER. 671 

give a reaction for chlorides. The precipitate is then dried on 
the filter, the precipitate and filter-paper burned, and the whole 
gently ignited in a crucible and weighed. This residue is 
magnesium pyroarsenate and has the formula Mg 2 As 2 7 . 

. ANTIMONY. 

The metal is precipitated in the form of sulphide (Sb 2 S 3 ), 
with the precautions observed in estimating arsenum — a small 
quantity of tartaric acid, as well as hydrochloric, being added 
to prevent the precipitation of an oxysalt. If the sulphuretted 
hydrogen be passed through a hot solution, the particles of pre- 
cipitate aggregate better, and the latter may be more quickly 
filtered and washed. The experiment may be performed on 
about i a gramme of pure tartar emetic ; the salt should yield 
nearly half its weight of sulphide. According to Fresenius, 
the sulphide dried at 100° C. still contains 2 per cent, of water, 
and must be heated in a current of carbonic acid gas until it 
turns from an orange to a black color before all moisture is 
expelled. In the British Pharmacopoeia the purity of tartar 
emetic (Antimonium Tartaratum), and the strength of solution 
of antimony chloride (Liquor Antimonii Chloridi'), are deter- 
mined by the above process. Of the Antimonmm Sulphura- 
tum, B. P., it is stated " that 60 grains moistened and warmed 
with successive portions of nitric acid until red fumes cease to 
be evolved, and then dried and heated to redness, give a white 
residue [Sb 2 4 ] weighing about 40 grains." 

(For the volumetric estimation of antimony in antimonious 
salts see p. 647.) 

COPPER. 

Copper is precipitated from its solutions and weighed either 
(1) as metal (Cu 2 ) or (2) as oxide (GuO). 

Process 1. — Dissolve about ^ a gramme of dry crystallized 
copper sulphate in a small quantity of water in a tared por- 
celain crucible or beaker, acidulate with hydrochloric acid, 
introduce a fragment or two of pure zinc, cover the vessel with 
a watch-glass, and set aside till evolution of hydrogen has 
ceased and the still acid liquid is colorless. The copper is then 
washed with hot water by decantation until no trace of acid 
remains, the precipitate drained, rinsed with strong spirit of 
wine, dried in the water-oven, cooled, and weighed. 

Process 2. — From a solution acidulated by sulphuric acid and 
placed in a platinum crucible copper may be entirely deposited 
in a coherent form by a weak current of electricity, the crucible 
being connected with the zinc pole of the battery, a platinum 



672 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

spatula suspended in the solution forming the positive pole. 
The crucible may afterward be freed from the deposited copper 
by nitric acid. 

Process 3. — About three-fourths of a gramme of copper sul- 
phate is accurately weighed, dissolved in \ a litre of water, 
the liquid boiled ; dilute solution of potash or soda is then 
added till no more precipitate falls, ebullition continued for a 
short time, and the beaker set aside ; the supernatant liquid is 
decanted, the precipitate boiled with water twice or thrice, col- 
lected on a filter, washed, dried, transferred to a crucible, the 
filter incinerated, and its ash moistened with a drop of nitric 
acid ; the whole is finally heated strongly, cooled, and weighed. 

249.3 parts of copper sulphate yield 79.3 of oxide or 63.3 
of metal. 

Other Processes. — Vide Pharmaceutical Journal for April 3, 
1880, p. 801. 

BISMUTH. 

Dissolve 0.3 or 0.4 of the pure bismuth oxycarbonate (Bi 2 2 - 
C0 3 ) 2 ,H 2 (Bismuthi Subcarbonas, U. S. P.) in a very small 
quantity of hydrochloric acid, dilute with water slightly acid- 
ulated by hydrochloric acid, pass excess of sulphuretted hydro- 
gen through the liquid, collect the precipitate on a tared filter, 
wash, dry at 100° C., and weigh. The sulphide must not be 
exposed too long in the water-oven or it will increase in weight, 
owing to absorption of oxygen ; hence it should be tested in the 
balance every half-hour during desiccation. 519 parts of oxy- 
carbonate should yield 514 of sulphide (Bi 2 S 3 ). The strength 
of the official solution (B. P.) of bismuth and ammonium 
citrate (Liquor Bismuthi et Ammonii Citratis, B. P.) is deter- 
mined by this process. " Two fluidrachms of the solution, 
mixed with an ounce of distilled water, and treated with sul- 
phuretted hydrogen in excess, yield a black precipitate, which, 
collected, washed, and dried, weighs about 7 grains. 1 fluid- 
drachm yields 3 grains of bismuth oxide' 1 (B. P.). Of the 
official Citrate of Bismuth, B. P., it is stated that u 10 grains 
dissolved in solution of ammonia and treated with sulphuretted 
hydrogen in excess, yield a precipitate which, when washed 
and dried, weighs about 7 grains ; " and of the Bismuth and 
Ammonium Citrate, B. P., " 10 grains dissolved in water and 
treated with sulphuretted hydrogen in excess, yield a precipi- 
tate which, when washed and dried, weighs about 6J grains" 
(B. P.). The atomic weight of bismuth is 208 if oxygen = 16, 
or 207.5 if oxygen = 15.96. The U. S. P. bismuth substances 
may be estimated similarly. 



ESTIMATION OF MERCURY. 673 

MERCURY. 

This element may be (1) isolated and estimated in the form 
of metal, or precipitated and weighed as (2) mercurous chloride 
or (3) mercuric sulphide. 

Process 1.— The process by which the metal itself is sepa- 
rated is one of distillation into a bulb surrounded by water. 
About £ a metre of the difficultly fusible German glass known 
as combustion-tubing is sealed at one end after the manner of a 
test-tube (Fig. 79) ; a mixture of sodium bicarbonate and dry 
chalk is then dropped into the tube to the height of two or 
three centimetres, and, next, several small fragments of quick- 
lime, so as to occupy another centimetre ; a mixture of about 

Figs. 79, 80, 81. 




a gramme of pure calomel or corrosive sublimate with enough 
quicklime to occupy ten or twelve centimetres of the tube is 
added, then the lime-rinsings of the mixing-mortar, a layer of 
a few centimetres of powdered quicklime, and, finally, a plug 
of asbestos. The whole should occupy two-thirds of the tube. 
The part of the tube just above the asbestos is now softened 
in the blowpipe flame and drawn out about a decimetre to the 
diameter of a narrow quill (Fig. 80) ; again drawn out to the 
same extent at a point two or three centimetres nearer the 
mouth (Fig. 80), and any excess of tubing cut off. The bulb 
thus formed may be enlarged by softening and blowing. The 
tube is next softened at a point close to but anterior to the 
asbestos, and bent to form an obtuse angle ; the tube is then 
softened close to the bulb and slightly bent so that the bulb 
may be parallel with the large tube ; then softened on the other 
side of the bulb, and the terminal tube bent to an obtuse angle, 
so that, the tube being held in a horizontal position, the bulb 
may be sunk in water and the terminal tube point upward (Fig. 
81). The long tube is now laid in the gas-furnace found in 
most laboratories (Fig. 82), a basin so placed that the bulb of 
the apparatus may be cooled by being surrounded by water, 
the part of the tube occupied by asbestos heated to redness, 
and the flame slowly lengthened until the whole tube is red hot. 
Under the circumstances just described the mercurial com- 



674 



GRAVIMETRIC QUANTITATIVE ANALYSIS. 



pound volatilizes, is decomposed by the lime, and its acidulous 
radical fixed, the mercury carried in vapor to and condensed in 
the bulb, the carbonic acid gas evolved from the sodium bicar- 
bonate and chalk washing out the last portions of mercury- 




Distillation of Mercury for Quantitative Purposes. 

vapor from the tube. When the distillation is considered to 
be complete, the dish of water is removed, the bulb dried, and 
then detached by help of a file at a point beyond any sub- 
limate of mercury. The dried bulb is weighed, the mercury 
shaken or dissolved out, and the tube again dried and weighed. 
The difference between the weights gives the weight of the 
mercury. "Ammoniated Mercury," B. P., should yield, theo- 
retically, 79.52 per cent., practically about 77.5 per cent., of 
metallic mercury. 

Process 2. — The process by which mercury is separated in 
the form of calomel consists in adding solution of hydrochloric 
and of phosphorous acids to an aqueous or even acid solution 
of a weighed quantity of the mercurial compound, setting the 
mixture aside for twelve hours, collecting the precipitate on a 
tared filter, washing, drying at 100° C, and weighing (Rose). 
The experiment may be tried on J a gramme to 1 gramme of 
corrosive sublimate. 

Process 3. — 2 or 3 decigrammes of corrosive sublimate are dis- 
solved in water, the solution acidulated with hydrochloric acid, 
excess of sulphuretted hydrogen passed through it, the pre- 
cipitate collected on a tared filter, washed with cold water, dried 
at 100° C, and weighed. 

Proportional Weights of Equivalent Quantities of Mercury and 
its Salts. 

Metal Hg 200 

Mercurous chloride . . . HgCl 235.4 

Mercuric chloride .... HgCl 2 270.8 

Mercuric sulphide .... HgS 232 



ESTIMATION OF LEAD AND SILVER. 675 

LEAD. 

Lead is generally estimated either as (1) oxide, (2) sulphate, 
(3) chromate, or (4) metal. 

Process 1. — Weigh out 1 or 2 grammes of pure lead acetate 
in a covered crucible, previously tared, and heat slowly until 
no more vapors are evolved. Remove the lid, stir down the 
carbonaceous mass with a clean iron wire, and keep the crucible 
in the flame so long as any carbon remains unconsumed. Intro- 
duce some fragments of fused ammonium nitrate, and again 
ignite until no metallic lead remains and all excess of the 
nitrate has been decomposed. Cool and weigh the resulting 
oxide (PbO). 

Process 2. — Dissolve 0.4 or 0.5 of a gramme of lead acetate 
in a small quantity of water, drop in diluted sulphuric acid, 
add to the mixture twice its bulk of methylated spirit of wine, 
and set aside. Decant the supernatant liquid, collect the sul- 
phate on a filter, wash with spirit, dry, transfer to a porcelain 
crucible, removing as much of the sulphate as possible from 
the paper, incinerate on the crucible-lid (not in the platinum 
coil, for the fused particles of reduced lead would alloy with 
the platinum), ignite, cool, and weigh. 

Process 3. — About % a gramme of lead acetate is dissolved 
in 200 or 300 cc. of water, acetic acid added, and -then solution 
of red potassium chromate. Collect the precipitate on a tared 
filter, wash, dry at 100° C, and weigh. 

Process 4- — I n certain cases, notably in that of commercial 
' k white lead," the lead may be estimated in the metallic state 
by means of potassium cyanide. The lead paint (about 20 
grammes) is weighed and carefully incinerated. The residue, 
a mixture of metallic lead and lead oxide, is then mixed with 
several times its bulk of potassium cyanide and the whole 
heated to fusion. With careful manipulation the lead collects 
in one globule, which, after cooling, may readily be separated 
from the mixed cyanide and cyanate and weighed. Commer- 
cially pure white lead should yield 74 per cent, of lead. 

Proportional Weights of Equivalent Quantities of Lead and its 
Salts. 

Metal Pb 206.4 

Acetate ........ Pb2C 2 H 3 2 ,2H 2 . . 378.4 

Oxide " . PbO 222.4 

Sulphate PbS0 4 302.4 

Chromate PbCrO, 322.9 

SILVER. 

Compounds of silver which are readily decomposed by heat 



676 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

are estimated in the form of (1) metal, others usually as (2) 
chloride (AgCl), but sometimes as (3) cyanide (AgCN). 

Process 1. — Heat about a gramme of silver oxide (Ag 2 0) in 
a tared crucible, cool, and weigh. 232 parts of oxide yield 216 
of metal. " 29 grains heated to redness yield 27 grains of metal- 
lic silver."— B. P. 

Process 2. — Dissolve 0.4 or 0.5 grm. of pure dry crystals of 
silver nitrate in water, acidulate with 2 or 3 drops of nitric 
acid, slowly add hydrochloric acid, stirring rapidly, until no 
more precipitate falls. Pour off the supernatant liquid through 
a filter, wash the silver chloride once or twice with hot water, 
transfer to the filter, complete the washing, and dry. After 
removing as much as possible of the precipitate from the paper 
to the crucible, burn the filter, not in a wire helix, but on the 
inverted lid of the crucible, moisten with a drop of nitric acid, 
warm, add a drop of hydrochloric acid, evaporate to dryness, 
replace the lid of the crucible, ignite the whole until the edges 
of the mass of chloride begin to fuse ; cool, and weigh. 170 
parts of nitrate yield 143.4 of chloride. According to the United 
States Pharmacopoeia, all silver salts should be estimated volu- 
metrically with standard sodium chloride solution. ( Vide p. 
657.) 30 parts of " Mitigated Caustic " (Argenti et Potassii 
Nitras, B. P.) should give 8.44 parts of silver chloride, and the 
nitrate yields potassium nitrate and chloride on evaporation. 
" Toughened Caustic," B. P., contains 5 per cent, of potassium 
nitrate ; hence 10 parts will give only 8 parts of silver chloride, 
and the filtrate will yield a little potassium salt. 10 parts of 
silver, if pure (Argentum Purification, B. P.), will give 13.285 
of silver chloride. 

Process 3. — Silver cyanide may be collected on a tared filter 
and dried at 100° C. 170 parts of nitrate yield 134 of cyanide. 
Silver and its salts may be volumetrically estimated by a stand- 
ard solution of sodium chloride. 

Cupellation. — The amount of silver in an alloy may also be deter- 
mined by a dry method. The metal is folded in a piece of thin 
sheet lead, placed on a cupel (cupella, little cup, made of com- 
pressed bone-earth) and heated in a furnace, the cupel being pro- 
tected from the direct action of the flame by a muff-shaped — or, 
rather, oven-shaped — case, termed a muffle. The metals melt, the 
baser become oxidized, the lead oxide fusing and dissolving the 
other oxides ; the fluid oxides are absorbed by the porous cupel, a 
button of pure silver remaining. An alloy suspected to contain 95 
per cent, of silver requires about three times its weight of lead for 
successful cupellation ; if 92J per cent. (English silver coin), between 
five and six times its weight of lead is necessary. 



ESTIMATION OF CHLORIDES AND IODIDES. 677 

QUESTIONS AND EXERCISES. 

Explain the gravimetric process by which the strength of the official 
solutions of ferric chloride, nitrate, and sulphate are determined. — Men- 
tion the various amounts of ferrous and ferric salts equivalent to 100 
parts of metal.— State the precautions necessary to be observed in esti- 
mating arsenum or antimony in the form of sulphide. — In what form are 
the official compounds of bismuth weighed for quantitative purposes ?— 
Give an outline of the process by which rnercury may be isolated from 
its official preparations and weighed in the metallic condition. — Describe 
three methods for the quantitative analysis of salts of lead, and the 
weights of the respective precipitates, supposing 0.56 of crystallized 
acetate to have been operated on in each case. — Describe the processes by 
which silver is estimated in the forms of metal, chloride, and cyanide. — 
What proportions of silver nitrate are indicated, respectively, by 15 of 
metal, 9.8 of chloride, and 8.1 of cyanide? — Describe cupellation. 



GRAVIMETRIC ESTIMATION 
OF THE ACIDULOUS RADICALS OF SALTS. 



CHLORIDES. 

Free chlorine (chlorine-water) and compounds which by 
action of acids yield free chlorine (chlorinated lime, chlorinated 
soda, and their official solutions) are estimated volumetrically 
by a standard solution of sodium hyposulphite. ( Vide p. 655.) 
The amount of combined chlorine in pure chlorides (HCl,NaCl) 
may also be determined by volumetric analysis with a standard 
solution of silver nitrate (p. 639). 

Combined chlorine is gravimetrically estimated in the form 
of silver chloride, the operation being identical with that just 
described for silver salts (p. 676). 58.4 parts of pure, color- 
less, crystallized sodium chloride (rock-salt) yield 143.4 of 
silver chloride. 

IODIDES. 

Free iodine is estimated volumetrically by solution of sodium 
hyposulphite. ( Vide p. 655.) 

Combined iodine is determined gravimetrically in the form of 
silver iodide, the operations being conducted as with silver 
chloride. Potassium iodide may be used for an experimental 
determination : KI = 166 should yield Agl = 235. Of cad- 
mium iodide (Cadmii lodidum, B. P. 1867) it is stated that 
"10 grains dissolved in water, and silver nitrate added in ex- 
cess, give a precipitate which, when washed with water and 
afterward with \ an ounce of solution of ammonia, and dried, 
weighs 12.5 grains." 



678 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

In presence of chlorides and bromides the iodine in iodides 
may be precipitated and weighed as palladium iodide. 

Moisture in iodine is estimated by loss on exposing a weighed 
quantity of iodine in a capsule over a dish of sulphuric acid 
under a small bell jar, or by adding to a weighed sample five 
or six times as much mercury or twice as much zinc, and a 
little water, drying, and weighing. The product is the amount 
of metal employed plus that of the dry iodine in the sample. 

BROMIDES. 

Free bromine may be estimated by shaking with excess of 
solution of potassium iodide, and then determining the equiv- 
alent quantity of liberated iodine by a standard solution of 
sodium hyposulphite (p. 655). 

The bromine in bromides may be precipitated and weighed as 
silver bromide, the manipulations being the same as those for 
silver chloride : 0.2 to 0.3 of pure potassium bromide may be 
used for an experimental analysis. 

Ammonium bromide and calcium bromide are estimated vol- 
umetrically. ( Vide p. 642.) 

CYANIDES. 

The hydrogen cyanide (hydrocyanic acid) is usually estimated 
volumetrically. ( Vide p. 640.) 

From all soluble cyanides cyanogen may be precipitated by 
silver nitrate after acidulating with nitric acid, the silver 
cyanide being collected on a tared filter, dried at 100°, and 
weighed. 

Silver Cyanide. 

In 1 molec. wt. In 100 parts. 

Silver Ag .... 107.66 . . . 80.55 

Cyanogen . . . ON .... 26.00 . . . 19.45 

133.66 100.00 

TITRATES. 

Nitrates cannot be estimated by direct gravimetric analysis, 
none of the basylous radicals yielding a definite nitrate insol- 
uble in water. With some difficulty they may be determined 
by indirect volumetric methods. 

Process. — The following (Thorpe's) method depends upon the 
fact (Gladstone and Tribe) that when zinc upon which copper 
is deposited in a spongy form is boiled with water, hydrogen is 
evolved. Thorpe found that in a solution containing nitrates 
the nascent hydrogen converts the whole of the nitrogen of 



ESTIMATION OF NITRATES. 



679 



the nitrates into ammonia, which may be collected and esti- 
mated. ' (The oxygen of the nitrate is simultaneously con- 
verted into water, the nitrate-metal into hydrate, and the zinc 
into zinc hydrate. The power of the copper-zinc couple is 
considered to depend largely on the hydrogen absorbed by the 
finely-divided metal.) 

Fig. 83. 




Estimation of Nitrates. 



An apparatus such as shown in Fig. 83 should be con- 
structed. A flask (about 100 cc.) is fitted with a clean sound 
cork perforated for a delivery-tube, which should be of strong 
glass tubing of about a quarter-inch bore, and for a stoppered 
funnel, which should have about half the capacity of the flask. 
The whole is supported by a clamp or on wire gauze. The 
outer jar shown in the figure should have a capacity of 2 or 3 
litres, and the inner receiving-jar should be capable of holding 
200 cc. The latter is fitted with a cork perforated for the 
delivery-tube, and perhaps for another tube containing frag- 
ments of glass moistened with acidulated water to prevent pos- 
sible loss of ammonia, though the latter tube is practically 
found to be almost unnecessary. The addition of washing- 
bottle tubes is also recommended, as convenient for obtaining 
the distillate from the jar without dismounting the apparatus 
from time to time. 

A few strips of clean zinc (granulated zinc recently cleansed 
with diluted acid is best) are boiled in a beaker with a 3 per 
cent, solution of copper sulphate, the operation being repeated 
with a fresh portion of solution until an adherent and fairly 



680 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

thick coating of finely-divided copper is deposited. The pieces 
of metal are well washed and introduced into the flask, which 
is then half filled with pure water free from ammonia. To 
avoid transference, the flask itself may be used instead of the 
beaker. The funnel also of the apparatus is filled with pure 
water. Water is now placed around the inner receiver in the 
outer jar, and, the connections being sound, heat is applied 
with the view of freeing the apparatus itself from any trace 
of ammonia. When the contents of the flask are evaporated 
nearly to dryness, pure water is admitted from the funnel until 
the flask is again about half full (the funnel should be filled 
again at once), and the distillation carried on as before. This 
must be repeated until no further trace of ammonia is evolved, 
when the apparatus is ready for use. On each occasion that 
the apparatus is used it must be freed from ammonia in this 
way. A suitable quantity of the substance to be estimated is 
now introduced (in the case of potable waters the prepared 
solid residue from 100 cc), and water added, if necessary, until 
the flask is half full. Heat is now applied and the operation 
conducted in the manner already described until ammonia ceases 
to come over — a point which usually occurs in the case of 
water-residues when the flask has been twice or thrice charged 
with water and the distillate is about 100 cc. The warm water 
from the upper part of the cooling-jar may be removed by a 
siphon or otherwise, cold water being introduced from time to 
time. 

The ammonia being all evolved, disconnect the flask and 
receiver simultaneously (unless washing-bottle tubes are fitted), 
and treat the contents of the latter by the Nessler method 

described on p. 630. Urea yields but traces of ammonia by 

this process, and neither the sulphates nor chlorides of the 
alkali-metals affect the result. The method is only appli- 
cable to highly dilute solutions of nitrates, for with stronger 
solutions oxides of nitrogen are formed and escape. 

Another process (Pelouze's, improved by Fresenius) consists 
in adding the nitrate to an acid solution of a ferrous salt of 
known strength, and, when reaction is complete, estimating the 
amount of ferrous salt unattacked by volumetric solution of 
red chromate or of permanganate. Three molecular weights 
of converted ferrous salt indicate one molecular weight of 
nitric acid. Regeneration of nitric or nitrous acids by aerial 
oxidation of the nitric oxide evolved is prevented either by a 
current of carbonic acid gas or by using a closed flask in which 
is a Bunsen valve. ( Vide p. 652.) 



ESTIMATION OF SULPHIDES. 681 

SULPHIDES. 

Process 1. — Soluble sulphides (H 2 S,NaHS, e. g.) may be 
estimated volumetrically by adding to the aqueous liquid a 
measured excess of an alkaline solution of arsenic of known 
strength, neutralizing by hydrochloric acid, diluting to any 
given volume, filtering off the arsenum sulphide precipitated, 
taking a portion of the filtrate equal to a half or a third of the 
original volume, and, after neutralizing by acid sodium car- 
bonate, estimating the residual arsenic by the standard iodine 
solution (videip. 64:6). The process may be tried on a measured 
volume of sulphuretted hydrogen (the weight of which is easily 
calculated ; 1 litre of hydrogen = 0.0896 gramme) absorbed 
by a strong solution of soda or potash. 

Process 2. — Sulphur and sulphides may also be quantita- 
tively analyzed by oxidizing to sulphuric acid and precipitating 
in the form of barium sulphate. A couple of decigrammes of 
a pure metallic sulphide may be decomposed by careful defla- 
gration with a mixture of potassium chlorate and sodium car- 
bonate, the product dissolved in water, acidulated with hydro- 
chloric acid, solution of barium chloride added, and the pre- 
cipitated barium sulphate washed and collected as described in 
connection with the estimation of barium (p. 665). Many sul- 
phides may be oxidized in a flask by potassium chlorate and 
hydrochloric acid, and then precipitated by barium chloride. 
Experimental determinations may also be made on a weighed 
fragment of sulphur, about 0.1, cautiously fused with a little 
solid caustic alkali, and the product oxidized while hot by the 
slow addition of powdered potassium nitrate or chlorate, or, 
when cold, by treatment with potassium chlorate and hydro- 
chloric acid, and subsequent precipitation by barium chloride. 

Note. — Fusions performed by help of a gas-lamp must be carefully 
conducted, for any alkali that may creep over the side of a crucible 
will certainly absorb sulphurous acid from the products of combus- 
tion of the gas, and error result. 

Process 3. — Soluble sulphides may also be treated with ex- 
cess of an alkaline arsenite, arsenous sulphide then be precipi- 
tated by the addition of hydrochloric acid, and the precipitate 
collected and weighed with the usual precautions. ( Vide p. 
670.) 

Weights of Equivalent Quantities of Sulphur and its Compounds. 

Sulphur S 32 

Sulphuretted hydrogen . H 2 S 34 

Barium sulphate .... BaS0 4 232.8 

Arsenous sulphide . . . (As 2 S 3 ) -f- 3 . . 82 

Iron bisulphide .... (FeS 2 j-=-2 ... 60 

Lead sulphide PbS 238.4 



682 GRAVIMETRIC QUANTITATIVE ANALYSIS. 



SULPHITES. 

Sulphites are usually estimated volumetrically by a standard 
solution of iodine. ( Vide p. 745.) Sulphites insoluble in water 
are diffused in that menstruum, hydrochloric acid added, and 
the iodine solution then dropped in. 

If necessary, sulphites may be estimated gravimetrically by 
oxidation and precipitation as barium sulphate. 



SULPHATES. 

These salts are always precipitated and weighed as barium 
sulphate, the manipulations being identical with those per- 
formed in the determination of barium by means of sulphates. 
( Vide p. 664.) The purity of sodium sulphate (Sodii Sulphas, 
U. S. P.), and the presence of not more than a given amount 
of sulphuric acid in vinegar (Acetum, B. P.), are directed, in 
the British Pharmacopoeia, to be ascertained by this process. 
10 grains of sodium sulphate yield 7.23 of barium sulphate. 
5 ounces of vinegar should yield not more than about i of a 
gramme of barium sulphate. 

Sulphates may be estimated volumetrically by a seminormal 
solution of pure barium chloride, BaCl 2 ,2H 2 = 244. 

The amount of free sulphuric acid or hydrochloric acid in 
vinegar, lemon-juice, lime-juice, etc. may also be ascertained 
volumetrically by adding a known quantity of standard solu- 
tion of soda, evaporating to dryness, incinerating, dissolving in 
water, and by standard acid estimating the quantity of soda 
still remaining free. The soda lost indicates the amount of free 
mineral acid (Hehner). Thresh first estimates the chlorine in 
a sample of vinegar, then adds a known additional amount of 
chlorine, preferably in the form of barium chloride, evaporates, 
ignites, treats with water, adds sodium bicarbonate to remove 
excess of barium, filters, and again estimates the chlorine. A 
loss of 70.8 of chlorine (Cl 2 ) indicates 98 of free sulphuric 
acid (H 2 S0 4 ). 

The method of estimating free sulphuric, nitric, or hydro- 
chloric acids proposed by Spence and Esilman is founded on 
their power of decolorizing a standard solution of ferric acetate. 

Proportional Weights of Equivalent Quantities of Sulphates. 

The sulphuric radical . . S0 4 96 

Sulphuric acid .... H ? S0 4 98 

Barium sulphate .... BaS0 4 232.8 







ESTIMATION OF CARBONATES. 683 

CARBONATES. 

Fig. 84. 

Carbonates are usually estimated by the 
loss in weight they undergo on the addition 
of a strong acid. 

Process 1. — A small light flask is se- 
lected — of such a size that it can be con- 
veniently weighed in a delicate balance. 
Two narrow glass tubes are fitted to the 
flask by a cork— the one straight, extending 
from about two or three centimetres above 
the cork to the bottom of the flask, the other Estimation of Car- 
cut off close to the cork on the inside and bonates. 
curved outward, so as to carry a thin drying-tube horizontally 
above the flask. (See Fig. 84.) The drying-tube is nearly 
filled with small pieces of calcium chloride, a plug of cotton- 
wool preventing escape of any fragments at either end, and is 
attached by a pierced cork to the free extremity of the curved 
tube of the flask. A weighed quantity of any pure soluble 
carbonate is placed in the flask, a little water added, a minia- 
ture test-tube containing sulphuric acid lowered into the flask 
by a thread and supported so that the acid may not flow out, 
the cork inserted, the outer end of the piece of the straight 
glass tubing closed by a cap or a fragment of cork, and the 
whole weighed. The apparatus is then inclined, so that the 
sulphuric acid and carbonate may slowly react ; carbonic acid 
gas is evolved and escapes through the horizontal tube, any 
moisture being retained by the calcium chloride. When effer- 
vescence has ceased, the gas still remaining in the vessel is 
sucked out ; this is accomplished by adapting a piece of india- 
rubber tubing to the end of the drying-tube, removing the 
small plug from the straight tube, and aspirating slowly with 
the mouth for a few minutes. If the heat produced by the 
action of the sulphuric acid and solution is considered insuf- 
ficient to expel all the carbonic acid from the liquid, the plug 
is again inserted in the tube and the contents of the flask 
gently boiled for some seconds. When the apparatus is nearly 
cold more air is again drawn through it, and the whole finally 
weighed. The loss is due to carbonic acid gas (C0 2 ), from the 
weight of which that of any carbonate is ascertained by cal- 
culation. Carbonates insoluble in water may be attacked by 
hydrochloric instead of sulphuric acid ; granulated mixtures 
of carbonates and powdered tartaric or citric acid, by enclosing 
the preparation in the inner tube and placing water in the 
or vice versa. The apparatus also may be modified in 



684 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

many ways to suit the requirements, convenience, or practice 
of the operator. 

Process 2. — Carbonates from which carbonic acid gas is 
evolved by heat may be estimated by the loss they experience 
on ignition. 

Process 3. — Free carbonic acid gas may be absorbed by a 
solid stick of potash or strong alkaline solution, the loss in 
volume of the gas or mixture of gases indicating the amount 
originally present. 

Weights of Equivalent Quantities of Carbonic Acid Gas and cer- 
tain Carbonates. 



Carbonic acid gas C0 2 44 

Carbonic acid H 2 C0 3 .... 62 

Anhydrous sodium carbonate . Na 2 C0 3 .... 106 

Crystalline sodium carbonate . Na 2 CO 3 ,10H 2 O . 286 

Anhydrous potassium carbonate K 2 C0 3 .... 138 

Crystalline potassium carbonate K 2 C0 3 + 16%Aq 164.285 

Calcium carbonate CaC0 3 .... 100 

OXALATES. 

Process 1. — The oxalic radical is usually precipitated in the 
form of calcium oxalate, and weighed as carbonate, the manip- 
ulations being identical with those observed in the estimation 
of calcium. ( Vide p. 665.) The experiment may be performed 
on 0.3 or 0.4 of a gramme of pure oxalic acid, 126 parts of 
which should yield 100 of calcium carbonate. 

Process 2. — Oxalates may also be determined by conversion 
of their acidulous radical into carbonic acid gas, and observa- 
tion of the weight of the latter. The oxalate, water, and ex- 
cess of black manganese oxide are placed in the carbonic-acid 
apparatus (p. 683), a tube containing sulphuric acid lowered 
into the flask, the whole weighed, and the operation completed 
as for carbonates. From the following equation it will be seen 
that every 88 parts of carbonic acid gas evolved indicates the 
presence of 126 parts of crystallized oxalic acid or an equiv- 
alent quantity of other oxalate : 

Na 2 C 2 4 + Mn0 2 + 2H 2 S0 4 = MnSO,+ Na 2 S0 4 -f2H 2 + 2C0 2 . 

The black manganese oxide used in this experiment must be 
free from carbonates. The amount of materials employed is 
regulated by the size of the vessels. 

PHOSPHATES. 

Process 1. — From phosphates dissolved in water the phos- 
phoric radical may be precipitated and weighed in the form of 



ESTIMATION OF PHOSPHATES. 685 

magnesium pyrophosphate, the details of manipulation being 
similar to those observed in estimating magnesium. ( Vide p. 
666.) i a gramme or rather more of pure dry crystallized 
sodium phosphate may be employed in experimental determina- 
tions. The official ammonium phosphate (Ammonii Phosphas, 
B. P.) is quantitatively analyzed by this method. " If 20 
grains of this salt be dissolved in water, and solution of mag- 
nesium ammonio-sulphate be added, a crystalline precipitate 
falls, which, when well washed upon a filter with solution of 
ammonia diluted with an equal volume of water, dried, and 
heated to redness, leaves 16.8 grains." J a gramme, or less, is 
a more convenient quantity if the operations be conducted with 
care. Solution of Ammonio-sulphate of Magnesium (B. P.) is 
prepared by dissolving 2 parts of magnesium sulphate, 1 of 
ammonium chloride, and 1 of solution of ammonia (20.6 per 
cent. NH 4 HO) in 18 or 20 of distilled water ; such a solution 
is of considerable use if several phosphoric determinations are 
about to be made. 

Process 2. — Free phosphoric acid is most readily determined 
as lead phosphate (Pb 3 2P0 4 ). Of the official (B. P.) diluted 
phosphoric acid it is stated that " 355 grains by weight (or 
73.8 of the official ' concentrated ' acid) poured upon 180 grains 
of lead oxide in fine powder leave, by evaporation, a residue 
(principally lead phosphate) which, after it has been heated to 
dull redness, weighs 215.5 grains." One-tenth of these quan- 
tities may be used for experimental purposes ; 1 to 2 grammes 
will give good results. The lead oxide must be quite pure ; it 
should be prepared by digesting red lead in warm diluted nitric 
acid, washing, drying, and heating the resulting puce-colored 
plumbic oxide in a covered porcelain crucible. The increase in 
weight obtained on evaporating a given amount of solution of 
phosphoric acid with a known weight of perfectly pure lead 
oxide (PbO) may be regarded as entirely due to phosphoric 
anhydride (P 2 5 ) ; 3PbO + P 2 5 = Pb 3 2P0 4 , the actual reac- 
tion being 3PbO -f 2H 3 P0 4 = Pb 3 2P0 4 + 3H 2 0. From these 
equations, and the atomic weights (vide Appendix or table on 
next page), the percentage of phosphoric acid (H 3 P0 4 ) in any 
specimen of its solution may easily be calculated. 

Process 3. — The Strength of Pure Solution of Phosphoric 
Acid. — This is ascertained by specific gravity and reference 
to tables. 

Process J^. — Bone earth, " superphosphate," the Calcis Phos- 
phas, and other forms of calcium phosphate known to be toler- 
ably free from iron or aluminium may be estimated by treat- 
ing about i a gramme with hydrochloric acid somewhat diluted, 
30 



686 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

filtering if necessary, warming, precipitating with excess of 
ammonia, collecting the precipitate (Ca 3 2P0 4 ), washing, drying, 
igniting, and weighing. The calcium phosphate of pharmacy 
(Calcii Phosphas, B. P.), if pure, will in this process lose little 
or no weight. 

Process 5. — Insoluble phosphates in ashes, manures, etc. are 
treated as follows : The weighed material (1.0 to 10.0 grammes) 
is digested in hydrochloric acid diluted with three or four 
times its bulk of water, filtered (insoluble matter and filter 
being thoroughly exhausted by water), ammonia added to the 
filtrate and washings, until, after stirring, a faint cloudy pre- 
cipitate is perceptible, solution of oxalic acid dropped in until, 
after agitation for a few minutes, the opalescence is destroyed, 
ammonium oxalate next added, the whole warmed, calcium 
oxalate removed by filtration, and the filtrate concentrated if 
very dilute, the liquid treated with citric acid in such quantity 
that ammonia when added in excess gives a clear lemon-yellow 
solution (Warington), magnesian mixture poured in (as in Pro- 
cess 1), and the precipitate of ammonio-magnesian phosphate 
collected, washed, dried, and weighed, as already described in 
connection with the estimation of magnesium. 



Relative Weights of Equivalent Quantities of Phosphoric Compounds. 

Phosphoric acid H 3 P0 4 98 

Magnesium pyrophosphate . (Mg 2 P 2 7 = 222) 

Lead phosphate (Pb 3 2P0 4 = 809.2) -^ 

Phosphoric anhydride . . . (P 2 5 = 142) -r- 

Calcium phosphate .... (Ca 3 2P0 4 = 310) -i- 
Calcium superphosphate . . (CaH 4 2P0 4 — 234) — 



2 = 111 
2=404.( 
2= 71 
2 = 155 
2 = 117 



QUESTIONS AND EXERCISES. 

What quantity of pure rock-salt is equivalent to 4.2 parts of silver 
chloride? Ayis. 1.71* — State the percentage of real potassium iodide con- 
tained in a sample of which 8 parts yield 10.9 of silver iodide. Ans. 
96.25. — What is the strength of a solution of hydrocyanic acid 10 parts 
of which, by weight, yield 0.9 of silver cyanide? Ans. 1.81 per cent. — 
How are nitrates quantitatively estimated? — By what processes may the 
strength of sulphides be determined ? — How much real sodium sulphate 
is contained in a specimen 10 parts of which yield 14.2 of barium sul- 
phate? Ans. -86.61 per cent. — Give details of the operations performed 
in the quantitative analysis of carbonates. — What amount of carbonic 
acid gas should be obtained from 10 parts of acid potassium carbonate 
(or bicarbonate) ? Ans. 4.4 parts. — To what operation and what propor- 
tions of materials does the following equation refer? 

Na 2 C 2 04 + Mn0 2 + 2H2SO4 = MnSO* + Na 2 S0 4 + 2H 2 + 2C0 2 . 

Explain the lead process for the estimation of phosphoric acid in the 
official solution. — State the amount of calcium superphosphate equivalent 
to 7.6 parts of magnesium pyrophosphate. Ans. 8.01 parts. 



ESTIMATION OF WATER. 687 

SILICATES. 

Silica (Si0 2 ) may be separated from alkaline silicates, or 
from silicates decomposable by hydrochloric acid, by digesting 
the substance in hydrochloric acid at a temperature of 70° to 
80° C. until completely disintegrated, evaporating to dryness, 
heating in an air-bath, again moistening with acid, diluting with 
hot water, filtering, washing, drying, igniting, and weighing. 

ESTIMATION OF WATER. 

Water and other matters readily volatilized are most usually 
estimated by the loss in weight which a substance undergoes 
on being heated to a proper temperature. Thus, in the British 
Pharmacopoeia, crystalline gallic acid (H 3 C 7 H 3 2 ,H 2 0) is stated 
to lose 9.5 per cent, of its weight at a temperature of 100° C, 
cerium oxalate (Ce 2 3C 2 4 ,9H 2 0) 52 per cent, on incineration, 
potassium carbonate about 16 per cent, on exposure to a red 
heat, quinine sulphate (2C 20 H 24 N 2 O 2 ,H 2 SO 4 ,7H 2 O) 15.2 per cent, 
at 100° C, sodium arsenate (Na 2 HAs0 4 ,7H 2 0) 40.38 per cent, 
at 149° C, sodium carbonate (Na 2 CO 3 ,10H 2 O) 62.94 per cent., 
sodium phosphate (Na 2 HP0 4 ,12H 2 0) 63 per cent., and sodium 
sulphate (Na 2 SO 4 ,10H 2 O) 55.9 per cent, at a low red heat: 
bismuth oxide heated to incipient redness is not to diminish in 
weight. Ferric oxyhydrate " yields about 10 per cent, of 
moisture." 

Process. — 1 or 2 grammes of substance is sufficient in ex- 
periments on desiccation, the material being placed in a watch- 
glass, covered or uncovered porcelain crucible, or other vessel, 
according to the temperature to which it is to be exposed. 

Rapid desiccation at an exact temperature may be effected 
by introducing the substance into a tube having somewhat the 
shape of the letter U, sinking the lower part of the tube into 
a liquid kept at a definite temperature by aid of a thermometer, 
and drawing or forcing a current of dry air slowly through the 
apparatus. Substances liable to oxidation may be desiccated 
in a current of dried carbonic acid gas. The weights of the 
U-tube before and after the introduction of the salt, and after 
desiccation, give the amount of water sought. In all cases 
the material must be heated until it ceases to lose weight. 
Occasionally it is desirable to estimate water directly by con- 
veying its vapor in a current of air through a weighed tube 
containing calcium chloride, and reweighing the tube at the 
close of the operation ; the increase shows the amount of water. 

Note. — Highly-dried substances rapidly absorb moisture from the 
air ; they must therefore be weighed quickly, enclosed, if possible, 



688 GEAVIMETRIC QUANTITATIVE ANALYSIS. 

in tubes (p. 660), a pair of clamped watch-glasses, or a crucible 
having a tightly-fitting lid. 

CARBON, HYDROGEN, OXYGEN, NITROGEN. 

The quantitative analysis of animal and vegetable substances is 
either proximate or ultimate. 

Proximate Quantitative Analysis includes the estimation of water, 
oil, albumen, starch, cellulose, gum, resin, alkaloids, acids, glu- 
cosides, ash. It requires the application of much theoretical know- 
ledge and manipulative skill, and cannot well be studied except 
under the guidance of a tutor. One of the best works on the sub- 
ject is by Rochleder, a translation of whose monographs will be 
found in the Pharmaceutical Journal, vol. i. 2d Ser., pp. 562, 610; 
vol. ii. 2d Ser., pp. 24, 129, 160, 215, 274, 420, 478. Another is by 
Prescott, " Outlines of Proximate Organic Analysis," Van Nostrand, 
New York. The fullest is by Dragendorff, translated by H. G. 
Greenish, "Plant Analysis." 

Ultimate Quantitative Organic Analysis can only be successfully 
accomplished with the appliances of a well-appointed laboratory — 
a good balance, a gas-furnace (p. 674) giving a smokeless flame 
(seven or eight centimetres wide and seventy or eighty centimetres 
long), special forms of glass apparatus, etc. The theory of the ope- 
ration is simple : A weighed quantity of a substance is burnt to 
carbonic acid gas (C0 2 = 44) and water (H 2 == 18), and these 
products collected and weighed ; 12 parts in every 44 of carbonic 
acid gas (= ^-) are carbon, 2 in every 18 of water (= \) are hydro- 
gen ; nitrogen, if present, escapes as gas. If nitrogen be a con- 
stituent, a second quantity is strongly heated with a mixture of 
sodium and calcium hydrates 5 these bodies then split up into oxides, 
oxygen, and hydrogen ; the oxygen burns the carbon of the sub- 
stance to carbonic acid gas, its hydrogen and nitrogen appearing as 
water and ammonia respectively ; the carbonic acid and water are 
disregarded, the ammonia collected and weighed in the form of the 
double platinum and ammonium chloride (PtCl 4 ,2NH 4 Cl = 442.8), 
of which 28 parts in every 442.8 are nitrogen. The difference 
between the sum of the weights of hydrogen and carbon and the 
weight of substance taken is the proportion of oxygen in the body, 
supposing nitrogen to be absent. If nitrogen is present, the differ- 
ence between the sum of the percentages of carbon, hydrogen, and 
nitrogen and 100 is the percentage of oxygen. Shortly, carbon is 
estimated in the form of carbonic acid gas, hydrogen as water, 
nitrogen as ammonia, and oxygen by difference. 

The following is the outline of the necessary manipulations : 
The source of the oxygen for the combustion of carbon and 
hydrogen is black copper oxide in coarse powder. 200 or 300 
grammes of this material are heated in a crucible to low red- 
ness for a short time to expel every trace of moisture — then 
transferred to store-tubes (Fig. 85) resembling test-tubes, half 
a metre long and having a slightly narrowed mouth, the tube 



CARBON, HYDROGEN, OXYGEN, NITROGEN. 689 

being held in a cloth to protect the hand while the hot oxide 
is being directly introduced into the mouth of the tube by a 
scooping motion. As soon as the well-corked tube is cool, the 
oxide is poured, portion by portion, into a similar tube (the 

Fig. 85. 



combustion-tube), but somewhat longer, drawn out to a quill 
(bent upward nearly to a right angle) at one end and not con- 
stricted at the mouth. Two such tubes are readily made by 
softening in the blowpipe-flame two or three centimetres of the 
central part of a tube about a metre long, and drawing the 
halves of the tube apart as shown in the following engraving 
(Fig. 86). The tubes are separated by melting the glass in 




the middle of the quilled portion. A few decigrammes of 
fused potassium chlorate should first be dropped into the tube. 
After 10 or 15 centimetres of oxide have been poured in, about 
a decigramme of the substance to be analyzed is dropped down 
the tube, then a few grammes of oxide, then another deci- 
gramme of substance, then more oxide, until 3 or 4 decigrammes 
of the body under examination have been added. The 15 or 
20 centimetres of alternate layers are next thoroughly mixed 
by a long copper wire having a short helix : more oxide is 
introduced, the wire cleansed by twisting the helix about in 
the pure oxide, and a plug of dried asbestos finally placed on 
the top of the oxide at about five centimetres from the mouth 
of the tube ; the tube is then securely corked and set aside. 
The substance operated on may be pure white sugar, powdered 
and dried ; the tube in which it is contained is weighed before 
and after the removal of the portions for combustion ; the loss 
is the quantity employed in the experiment. The combustion- 
furnace may be such as shown on p. 674. If the furnace is 
very powerful or the combustion-tube not of the hardest glass, 
the tube should be enclosed in wire-gauze the elasticity of 
which has been destroyed by heating to redness. If the sub- 
stance under experiment contain nitrogen, the plug of asbestos 



690 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

must be displaced by a roll of copper gauze, which serves to 
reduce any oxides of nitrogen and thus ensure the escape of 
nitrogen itself — or dry yellow potassium chromate may be used 
(Perkin). The water produced when the prepared tube is 
he'ated is collected in a small U-tube containing pieces of cal- 
cium chloride or pumice-stone moistened with sulphuric acid 
(Fig. 87) ; the carbonic acid gas in a series of bulbs (Fig. 87) 




Calcium Chloride Tube and Potash-bulbs. 

containing solution of potash (sp. gr. about 1.27). These 
bulbs may be purchased at any apparatus-shop. The calcium 
chloride tube is fitted by a good cork to the combustion-tube, 
the potash-bulbs by a short piece of india-rubber tubing to the 
calcium chloride tube. The potash-bulbs may carry a short 
light tube containing a rod of caustic potash three or four 
centimetres long : this serves to arrest any moisture that might 
be carried away from the solution of potash by the dried ex- 
panded air which escapes during the operation. The combus- 
tion-tube having been placed in the furnace, and the drying-tube 
and potash-bulbs weighed and attached, the gas is lit under 
the asbestos, and, when the tube is red hot, the flame slowly 
extended until nearly the whole tube is at the same tempera- 
ture, the operation being conducted at such a rate that bub- 
bles of gas escape through the potash-bulbs at about the rate 
of one per second. When no more gas passes, the extremity 
of the tube containing the potassium chlorate is gently heated 
until oxygen ceases to be evolved ; perfect combustion of car- 
bon and removal of all carbonic acid gas are thus ensured. The 
heating of the chlorate must be very carefully conducted, or 
the evolution of oxygen may become sufficiently rapid to blow 
some of the fluid out of the potash-bulbs. The drying-tube 
and bulbs are disconnected and weighed, the increase in weight 
due to carbonic acid gas and water respectively noted, and the 
percentages of carbon, hydrogen, and (by loss) oxygen calcu- 
lated. This method is that of Liebig, with modifications by 
Bunsen : good combustion-furnaces are those known as Hof- 
mann's, Griffin's, and others. 






CARBON, HYDROGEN, OXYGEN, NITROGEN. 691 

Lead chromate can be used for combustions in place of copper 
oxide. The advantages are its less hygroscopic nature and the 
greater readiness with which it yields its oxygen to organic 
bodies when heated with them. It must not, however, be used 
with bodies containing nitrogen, since it would convert so large 
a proportion of the nitrogen into nitric oxide or higher oxide 
of nitrogen that it would be necessary to use an inconveniently 
long layer of the metallic copper to reduce these oxides, and so 
prevent their absorption in the series of bulbs containing the 
solution of potash. Organic bodies, however, containing sul- 
phur, bromine, iodine, or chlorine are burnt with advantage by 
means of lead chromate. If copper oxide were used with 
bodies containing sulphur, it would be necessary to place an 
additional tube containing lead peroxide between the calcium 
chloride tube and the potash-bulbs in order to absorb the sul- 
phurous anhydride formed ; this is entirely obviated by using 
lead chromate, which itself retains the whole of the sulphur. 
Again, if bodies containing chlorine, iodine, or bromine are 
burnt by means of copper oxide, then volatile chloride, iodide, 
or copper bromide is formed, and, collecting in the calcium 
chloride tube, vitiates the result with regard to the hydrogen ; 
by using lead chromate, however, the chlorine, iodine, and 
bromine are respectively retained in the combustion-tube as 
lead chloride, bromide, and iodide. 

In order to render the chromate fit for use it is first fused 
and poured out on a clean iron plate ; when cool, it is powdered 
and heated in a long tube throughout its whole length, while 
air, dried by passing through calcium chloride or strong sul- 
phuric acid, is drawn over it ; when the color of the chromate 
changes to brown, the heat can be withdrawn and the extremity 
of the tube farthest from the drying-apparatus closed, so that 
the air in passing into the tube on cooling may be quite dry ; 
when cool, the drying-tube is removed, and the extremity 
securely corked ; the lead chromate is then ready for direct 
transference to the combustion-tube. 

The general manipulations for substances containing nitrogen 
resemble the foregoing so far as the use of a combustion-tube 
and furnace and collection of the ammoniacal gas are concerned. 
The combustion-tube must be quilled at one end and about a 
third of a metre long. The soda-lime is made by slaking 
quicklime with a solution of soda of such a strength that about 
2 parts of quicklime shall be mixed with 1 of sodium hydrate, 
drying the product, heating to bright redness, and finely pow- 
dering ; it should be preserved in a well-closed bottle. Some 
of the soda-lime is introduced into the tube, then layers of sub- 




692 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

stance and soda-lime, mixture effected by a wire, a good layer 
of soda-lime added, and a plug of asbestos. Bulbs (Fig. 88), 

known as those of Will and 
Fig. 88. Varrentrapp (the originators of 

the method), containing hydro- 
chloric acid of about 25 per 
cent., are then fitted by a cork, 
and the tube heated in the fur- 
nace — to a not too bright red 
heat, or some of the produced 
ammonia eras may be decom- 

Nitrogen-bulbs. , ,, T 9 J 

posed. When gas ceases to pass 
and combustion is considered to be quite complete, the tube is 
allowed to cool somewhat, the quill is then broken, and aspira- 
tion continued slowly until all ammoniacal gas may be con- 
sidered to have been absorbed by the acid. The bulbs are dis- 
connected, their contents and rinsings poured into a small dish, 
solution of platinum perchloride added, and the operation com- 
pleted as in the estimation of potassium and ammonium salts. 
( Vide pp. 661 and 663.) Or the ammonia may be absorbed by 
a known quantity of standard sulphuric acid, of which the 
residual excess is estimated by a standard alkali ; certain obvious 
calculations then giving the amount of ammonia produced. 

Conversion into ammonia may also be effected by heating the 
substance with strong sulphuric acid, and, if not then thoroughly 
attacked, with potassium permanganate (Kjeldahl). Or the 
nitrogen may be evolved as gas by heating with copper oxide 
and copper turnings (p. 690), and be collected over alkali, and 
its volume, and thus indirectly its weight, be determined. 

Liquids are analyzed by a similar method to that adopted for 
solids, volatile liquids being enclosed in small bulbs having a 
long quill. These are weighed previously to and after the in- 
troduction of the liquid ; just before being dropped into the 
combustion-tube the quill is broken. Solids are also sometimes 
similarly burnt from a small boat placed in the tube, a con- 
tinuous current of purified air being used. 

Formulae. — From the percentage composition of an organic 
substance an empirical formula may be deduced by dividing the 
weight of each constituent by its atomic weight, and convert- 
ing the product into the simplest whole numbers ; a rational 
formula by ascertaining the proportion in which the substance 
unites with a radical or body having a known combining pro- 
portion, etc. ( Vide pp. 386-389.) 

Chlorine, Bromine, or Iodine contained in an organic substauce 
may be estimated by heating with fuming nitric acid and silver 



QUININE. 693 

nitrate in a sealed tube, or by heating to redness a given weight of 
the material with ten times as much pure lime in a combustion-tube. 
Calcium chloride, bromide, or iodide is thus produced. While still 
hot the tube is plunged into water, the mixture of broken glass and 
powder treated with pure diluted nitric acid in very slight excess ; 
the filtered liquid precipitated by silver nitrate, and the silver 
chloride, bromide, or iodide collected, washed, dried, cooled, and 
weighed. 

Sulphur, Phosphorus, and Arsenum in organic salts may be esti- 
mated by heating with fuming nitric acid in a sealed tube, or by 
gradually heating in a combustion-tube 1 part of the substance with 
a mixture of 10 parts nitre, 2 dried sodium carbonate (in order to 
moderate deflagration), and 20 sodium chloride. The product is 
dissolved in water acidulated by nitric acid, the sulphuric radical 
precipitated and estimated as barium sulphate, the phosphoric and 
arsenic radicals as ammonio-magnesian phosphate or arsenate. 

Limit of Experimental Errors. — Two determinations of carbon 
may vary to the extent of 0.1 per cent. 5 of hydrogen, 0.2 ; of nitro- 
gen, 0.3. 



QUININE, ETC. 

Process of the British Pharmacopoeia for ascertaining the amount of 
(1) Quinine with Cinchonidine, and (2) Total Alkaloids in the 
Succirubra or Red Cinchona Bark (Cinchonce Rubra? Cortex, 
B. P.). 

1. For Quinine and Cinchonidine. — Mix 200 grains of red 
cinchona-bark, in No. 60 powder, with 60 grains of calcium hydrate ; 
slightly moisten the powder with J an ounce of water ; mix the 
whole intimately in a small porcelain dish or mortar 5 allow the mix- 
ture to stand for an hour or two, when it will present the characters 
of a moist, dark-brown powder, in which there should be no lumps 
or visible white particles. Transfer this powder to a 6-ounce flask, 
add 3 fluidounces of a mixture of three volumes of commercial benzol 
and one volume of amylic alcohol (" benzolated amylic alcohol," 
B. P.) ; boil them together for about half an hour, decant and drain 
off the liquid on to a filter, leaving the powder in the flask ; add 
more of the benzol liquid to the powder, and boil and decant as 
before ; repeat this operation a third time : then turn the contents of 
the flask on to the filter and wash by percolation with more of the 
liquid until the bark is exhausted. If, during the boiling, a funnel 
be placed in the mouth of the flask, and another flask filled with 
cold water be placed in the funnel, this will form a convenient con- 
denser which will prevent the loss of more than a small quantity of 
the boiling liquid. Introduce the collected filtrate, while still warm, 
into a stoppered glass separator ; add to it 20 minims of diluted hydro- 
chloric acid, mixed with 2 fluidrachms of water ; shake them well 
together, and when the acid liquid has separated, this may be 
drawn off, and the process repeated with distilled water slightly 
acidulated with hydrochloric acid until the " whole of the alka- 
30 * 



694 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

loids have been removed. The acid liquid thus obtained will con- 
tain the alkaloids as hydrochlorates, with excess of hydrochloric acid. 
It is to be carefully and exactly neutralized with ammonia, and then 
concentrated to the bulk of 3 fluidrachms. If now about 15 grains 
of tartarated soda, dissolved in twice its weight of water, be added 
to the neutral hydrochlorates, and the mixture stirred with a glass 
rod, insoluble quinine and cinchonidine tartrates will separate com- 
pletely in about an hour ; and these, collected on a filter, washed, 
and dried, will contain eight-tenths of their weight of the alkaloids 
quinine and cinchonidine, which, divided by 2, represents the per- 
centage of those alkaloids. The other alkaloids will be left in the 
mother-liquor. 

2. For Total Alkaloids. — To the mother-liquor from the preceding 
process add solution of ammonia in slight excess. Collect, wash, 
and dry the precipitate, which will contain the other alkaloids. The 
weight of this precipitate divided by 2, and added to the percentage 
weight of the quinine and cinchonidine, gives the percentage of 
total alkaloids. 

Note. — If it is desired to obtain each alkaloid separately, the above 
process may be modified by using dilute sulphuric instead of hydro- 
chloric acid for removing the alkaloids from the benzolated amylic 
alcohol, and exactly neutralizing with ammonia while kept hot on a 
water-bath ; on cooling, the quinine will crystallize out almost com- 
pletely as neutral sulphate. The cinchonidine may then be precipi- 
tated from the filtrate by tartarated soda, and, after its removal, 
quinidine, if present, by potassium iodide ; finally, cinchonine is 
obtained by precipitating the filtrate from the quinidine with soda 
or ammonia. 

Extractum Cinchonse Liquidum, B. P. — The greater portion 
of the alkaloids of red cinchona-bark is dissolved out by water 
acidulated by hydrochloric acid and containing glycerin. The 
acid in acting as a solvent probably more or less decomposes 
the natural compounds of the bark. The glycerin contributes 
to the permanence of the preparation. The mixture is evap- 
orated to a low bulk, assayed as follows, and further evaporated 
or diluted until 85 fluid parts contain 5 of total alkaloids. 12f 
fluid parts of rectified spirit are then mixed in, and a little 
water added to make 100 fluid parts. The assay is thus con- 
ducted : Place 50 fluid grains of the product of the first evap- 
oration (a) with n an ounce of distilled water in a stoppered 
glass separator capable of holding 4 fluidounces ; add to this 
1 fluidounce of benzolated amylic alcohol and i a fluidounce of 
solution of soda ; shake them together thoroughly and repeat- 
edly, then allow them to remain at rest until the spirituous 
solution of the alkaloids shall have separated and formed a 
distinct stratum over the dark-colored alkaline solution of the 
other constituents of the extract. Run off the latter by the 
stopcock, add a little more distilled water to wash away any 



QUININE. 695 

adhering alkaline solution from the separator and its contents, 
and, having run off this as before as completely as possible, 
decant the spirituous solution into a small porcelain or glass 
dish the weight of which is known. Evaporate by the heat of 
a water-bath until a perfectly dry residue is left. The weight 
now of the dish and its contents, after deducting the known 
weight of the dish, will give that of the alkaloids, and this 
multiplied by 2 will give the parts by weight of the alkaloids 
in 100 fluid parts of the liquid (a). 

De Vrifs Method for the Separation of the Mixed Alkaloids 
from Cinchona Barks ; Be Vrifs Method for the Separation 
and Quantitative Determination of all the different Cinchona 
Alkaloids. For these processes the reader is referred to the 
eleventh edition of this Manual. Prolliuss Method for the 
Estimation of Total Alkaloids in Cinchona Bark as modified 
hy De Vrij. — See the thirteenth edition. 

Official (B. P.) Methods of Testing Quinine Sulphate for Sulphates 
of other Alkaloids. 

Test for Cinchonidine and Cinchonine. — Heat 100 grains of quinine 
sulphate in 5 or 6 ounces of boiling water, with 3 or 4 drops of 
diluted sulphuric acid. [Paul recommends omission of all acid, 
except what may be required to ensure perfect neutralization.] Set 
the solution aside until cold. Separate, by filtration, the purified 
quinine sulphate which has crystallized out. [Evaporate to one- 
fifth.] To the filtrate, which should nearly fill a bottle or flask, add 
ether, shaking occasionally, until a distinct layer of ether remains 
undissolved. Add ammonia in very slight excess, and shake thor- 
oughly, so that the quinine at first precipitated shall be redissolved. 
Set aside for some hours or during a night. Remove the supernatant 
clear ethereal fluid, which should occupy the neck of the vessel, by 
a pipette. Wash the residual aqueous fluid and any separated crys- 
tals of alkaloid with a very little more ether, once or twice. Collect 
the separated alkaloid on a tared filter, wash it with a little ether, 
dry at 212° F. (100° C), and weigh. 4 parts of such alkaloid cor- 
respond to 5 parts of crystallized cinchonidine sulphate or of cincho- 
nine sulphate. 

Test for Quinidine. — Recrystallize 50 grains of the original qui- 
nine sulphate as described in the previous paragraph. To the filtrate 
add solution of potassium iodide, and a little spirit of wine to prevent 
the precipitation of amorphous hydriodates. Collect any separated 
quinidine hydriodate, wash with a little water, dry, and weigh. The 
weight represents about an equal weight of crystallized quinidine 
sulphate. 

Test for Cupreine. — Shake the recrystallized quinine sulphate, 
obtained in testing the original quinine sulphate for cinchonidine 
and cinchonine, with 1 fluidounce of ether and a \ of an ounce of 
solution of ammonia, and to this ethereal solution, separated, add the 



696 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

ethereal fluid and washings also obtained in testing the original 
sulphate for the two alkaloids just mentioned. Shake this ethereal 
liquor with a \ of a fluidounce of a 10 per cent, solution of caustic 
soda, adding water if any solid matter separates. Remove the 
ethereal solution. Wash the aqueous solution with more ether, and 
remove the ethereal washings. Add diluted sulphuric acid to the 
aqueous fluid, heated to boiling, until the soda is exactly neutralized. 
When cold collect any cupreine sulphate that has crystallized out on 
a tared filter 5 dry, and weigh. 

" Quinine sulphate" should not contain much more than 5 per 
cent, of sulphates of other cinchona alkaloids. 

Quinine sulphate normally contains 15.2 per cent, of water ; cin- 
chonidine sulphate, 7.0 per cent. ; cinchonine sulphate 6.0 per cent., 
— all given off at 100° to 115° C. The drying should therefore be 
effected at 120° C, and the dried salt weighed in well-fitting weighing 
tubes. 100 parts of cinchonidine are equivalent to 116 parts of 
anhydrous cinchonidine sulphate. 

Cinchonidine sulphate is almost the only salt likely to be accident- 
ally present in the quinine sulphate of trade, much quinidine being 
rarely present in bark, and cinchonine sulphate being sufficiently 
soluble to remain dissolved in the mother-liquors of quinine sul- 
phate. Cinchonidine sulphate may vary from 1 to 18 per cent., but 
more usually is present to the extent of about 6 per cent. 

Quinina, U. S. P. — " If 2 grms. of quinine be mixed, in a small 
mortar, with 1 grm. of ammonium sulphate and 10 cc. of distilled 
water, the mixture thoroughly dried on a water bath, the residue 
(which should be strictly neutral to test-paper) agitated with 20 cc. 
of water, then allowed to macerate for half an hour at 15° C. 
(59° F.), with occasional agitation, and filtered through a pellet of 
glass-wool, 5 cc. of the filtrate, transferred to a test-tube, and gently 
mixed, without shaking, with 7 cc. of ammonia-water (specific 
gravity 0.960), should produce a clear liquid. If the temperature 
during the maceration has been 16° C. (60.8° F.), 7.5 cc. of ammonia- 
water may be added ; if 17° C. (62.8° F.), 8 cc. (In each case a 
clear liquid indicates the absence of more than small proportions of 
other cinchona alkaloids.)" 

Quinince Sulphas, U. S. P. — " If 2 grms. of the salt (which must 
have been previously ascertained to be strictly neutral to litmus- 
paper, or have been rendered so) be dried, as far as possible, at 100° 
C. (212° F.), the residue then agitated with 20 cc. of water, and the 
mixture macerated for half an hour at 15° C. (59° F.), with occasional 
agitation, upon proceeding further as directed above for Quinine 
the results there given should be obtained." 

Be Vrifs Chr ornate Test for the Purity of Quinine Sulphate. — ■ 
The purity of quinine sulphate may be tested in the following 
manner (De Vrij) : 

Dissolve 1 grm. of the salt in 40 cc. of hot distilled water, and add 
6 cc. of a 5 per cent, solution of pure yellow potassium chromate. 
Set aside for several hours at a temperature not above 15° C., when 
the quinine will be completely precipitated as chromate. Filter, and 
after adding a few more drops of the chromate to the filtrate, to 



MORPHINE. 697 

make sure that the precipitation has been completed, add 9 or 10 
drops of a 5 per cent, solution of soda. If the quinine sulphate was 
pure, the solution will remain clear, even after a day's standing; 
but if cinchonidine was present, that alkaloid will be precipitated, 
and may be filtered off and weighed. 

Of the Citrate of Iron and Quinine {Ferri et Quinince Citras, 
U. S. P. and B. P.) it is officially (B. P.) stated that " 50 grains dis- 
solved in a fluidounce of water and treated with a slight excess of 
ammonia give a white precipitate, which, when dissolved by success- 
ive treatments of the fluid with ether or chloroform, and the latter 
evaporated and the residue dried {at about 250° F.) until it ceases to 
lose weight, weighs seven and a half grains. The precipitate is 
almost entirely soluble in a little pure ether." Metric weights may 
be used. The British preparation should thus yield 15 per cent., 
and that of the United States at least 11.5 per cent., of quinine. 

A Process for the Determination of the Quinine of the Scaled 
Compound. — To the residue obtained as stated in the foregoing 
paragraph is added about 25 cc. of water and enough diluted sul- 
phuric acid to impart a decidedly acid reaction. The mixture is 
next heated over a water-bath until, the solution remaining acid, 
the residue has completely dissolved. Dilute soda solution is after- 
ward added with great care until the solution is exactly neutral. 
The dish is then removed, and the solution allowed to cool and rest 
over night, when the quinine will have separated in crystals of 
ordinary sulphate. These should be collected on a filter and the 
mother-liquor tested with litmus-paper. If it is acid, it must be 
warmed over a water-bath and dilute soda solution added to exact 
neutralization, and the solution set aside as before, when some more 
crystals will probably separate. These are also collected, and with 
the former ones washed, dried at 120° C, and weighed [(C 20 H 24 N 2 O 2 ) 2 ,- 
H 2 S0 4 — 746]. To this weight must be added 1 grm. for 750 cc. of 
mother-liquor for quinine sulphate which it retains. From this 
weight of anhydrous quinine sulphate is calculated its equivalent of 
hydrous quinine (C 20 H 24 N 2 O 2 ) 2 ,2H 2 O = 684, the approximate formula 
of hydrous quinine dried over a water-bath. The weight thus 
obtained is compared with the weight of total alkaloid determined, 
both having been reduced to percentages. The amount of hydrous 
quinine calculated from the crystals of sulphate should not be much 
below that weighed directly. In good specimens the difference will 
be about 1 per cent. 

Quinine sulphate should yield, according to De Vrij, at least 91.6 
per cent, of quinine tartrate. 

(See a paper by Fletcher in the Pharmaceutical Journal for Sep- 
tember 20, 1869 ; also in that for September 18, 1880, by De Vrij ; 
and in the Chemist and Druggist for October, 1885, by Howard.) 

MORPHINE. 

The official (U. S. P.) process for the assay of opium is con- 
ducted in the following manner : Opium, in any condition to 
be Valued, 10 grms. ; ammonia-water, 3.5 cc. ; alcohol, ether, 



698 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

water T each a sufficient quantity. " Introduce the opium 
(which, if fresh, should be in very small pieces, and if dry 
in very fine powder) into a bottle having a capacity of about 
300 cc, add 100 cc. of water, cork it well, and agitate fre- 
quently during twelve hours. Then pour the whole as evenly 
as possible upon a wetted filter having a diameter of 12 cm., 
and, when the liquid has drained off, wash the residue with 
water, carefully dropped upon the edges of the filter and the 
contents, until 150 cc. of filtrate are obtained. Then carefully 
transfer the moist opium back to the bottle by means of a 
spatula, add 50 cc. of water, agitate thoroughly and repeatedly 
during fifteen minutes, and return the whole to the filter. When 
the liquid has drained off wash the residue as before, until the 
second filtrate measures 150 cc, and finally collect about 20 cc. 
more of a third filtrate. Evaporate in a tared capsule, first, 
the second filtrate to a small volume, then add the first filtrate, 
rinsing the vessel with the third filtrate, and continue the 
evaporation until the residue weighs 14 grms. Rotate the con- 
centrated solution about in the capsule until the rings of 
extract are redissolved, pour the liquid into a tared Erlen- 
meyer flask having a capacity of about 100 cc, and rinse the 
capsule with a few drops of water at a time, until the entire 
solution weighs 20 grms. Then add 10 grms. (or 12.2 cc.) of 
alcohol, shake well, add 25 cc. of ether, and shake again. Now 
add the ammonia-water from a graduated pipette or burette, 
stopper the flask with a sound cork, shake it thoroughly during 
ten minutes, and then set it aside, in a moderately cool place, 
for at least six hours or over night." 

" Remove the stopper carefully, and, should any crystals 
adhere to it, brush them into the flask. Place in a small 
funnel two rapidly-acting filters, of a diameter of 7 cm., 
plainly folded, one within the other (the triple fold of the 
inner filter being laid against the single side of the outer 
filter), wet them well with ether, and decant the ethereal 
solution as completely as possible upon the inner filter. Add 
10 cc. of ether to the contents of the flask, rotate it, and again 
decant the ethereal layer upon the inner filter. Repeat this 
operation with another portion of 10 cc. of ether. Then pour 
into the filter the liquid in the flask, in portions, in such a way 
as to transfer the greater portion of the crystals to the filter, 
and, when this has passed through, transfer the remaining 
crystals to the filter by washing the flask with several portions 
of water, using not more than about 10 cc. in all. Allow the 
double filter to drain, then apply water to the crystals, drop by 
drop, until they are practically free from mother-water, and 



MORPHINE. 699 

afterward wash them, drop by drop from a pipette, with alco- 
hol previously saturated with powdered morphine. When this 
has passed through displace the remaining alcohol by ether, 
using about 10 cc. or more if necessary. Allow the filter to 
dry in a moderately warm place at a temperature not exceed- 
ing 60° C. (140° F.), until its weight remains constant, then 
carefully transfer the crystals to a tared watch-glass and weigh 
them. The weight found, multiplied by 10, represents the 
percentage of crystallized morphine obtained from the opium." 

Teschemacher and Smith's Method. — Thoroughly exhaust 200 
grains of opium with warm distilled water. Concentrate this 
watery extract to a thin syrup in a shallow dish over a water- 
bath, the water of which should not quite boil. Transfer this 
thin syrup to a suitable flask, which permits the use of a soft 
cork, using a few drops of water successively to wash out the dish. 
Add to the contents of the flask 50 fluid grains of alcohol, sp. gr. 
about 0.820, and about 600 fluid grains of ether. Mix gently, but 
thoroughly, and then add some 50 fluid grains of ammonia, sp. gr. 
0.935. Shake the contents of the flask well to precipitate the alka- 
loids in arenaceous crystals, with occasional agitation during the 
ensuing eighteen hours. Transfer the contents of the flask to 
a vacuum filter, and permit all the adherent liquid to be drawn 
away, washing out the flask with morphinated spirit,* and continue 
its use till the liquid passes colorless. Then wash with morphin- 
ated waterf till this also passes colorless. Now dry, slowly at first, 
finishing at 212° F. Transfer the dried substance to a mortar, re- 
duce it to a very fine powder, and digest it thoroughly in benzene 
to dissolve the narcotine and such of the opium alkaloids, other 
than morphine, which may be present. Transfer this mixture to 
a vacuum filter, wash out the mortar carefully with benzene, which 
use to wash the powder thoroughly. This, then, will be morphine, 
free from other opium alkaloids and narcotine, but still containing 
coloring and possibly other organic matters to the extent of 3 to 10 
per cent. Dry and weigh this powder. Now ascertain the per- 
centage by weight of crystallized morphine by titration of this 
powder with standard hydrochloric acid and litmus as the indicator. 
(This acid is so made that 1000 grains by weight shall exactly neu- 
tralize 100 grains of pure morphine crystallized from water, washed 
with ether, and gently dried finally at 212° F.) 

Of Morphine Hydrochlorate it is officially (in the TS. P.) stated that 
" 20 grains of the salt, dissolved in J an ounce of warm water, with 
ammonia added in the slightest possible excess, give on cooling a crys- 
talline precipitate which, when washed with a little cold water and 
dried in a water-bath, weighs 16 grains ;" and respecting the Injectio 
Morphince Hypodermica, B. P., " a fluidrachm of it, rendered slightly 
alkaline by the addition of solution of ammonia, yields a precipitate of 



* Morphinated Spirit. — Digest a large excess of morphine in rectified sprit 

of 80 per cent, for several days, with frequent agitation. Filter for use. 

t Morphinated Water. — As above, substituting distilled water for spirit. 



700 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

morphine which, after being washed and dried, should weigh 4.25 
grains, corresponding to 6 grains of acetate of morphine." The 
acetate {Morphince Acetas, U. S. P.) is liable to lose acetic acid 
and become basic ; hence in the British Pharmacopoeia the official 
morphine acetate must conform to the following requirements : " 20 
grains of the salt form with 1 drachm of water a slightly turbid 
solution, which is rendered clear by the addition of 1 grain of 
acetic acid ; and this solution, when mixed with ammonia in slight 
excess, yields a precipitate which, after washing with a little cold 
water and drying in a water-bath, weighs 15 grains. If the salt 
yields a larger proportion of morphine than this, it should be 
recrystallized from hot water acidulated with acetic acid." 

NUX- VOMICA ALKALOIDS. 

The British Pharmacopoeia directs that its two galenical 
preparations of nux vomica (Extractum JVucis Vomicae and 
Tiuctura JVucis Vomicae) shall contain defined proportions of 

the mixed alkaloids of the drug. The extract is made by 

exhausting a pound of powdered nux vomica with a mixture 
of 64 fluidounces of rectified spirit and 16 of water by per- 
colation. 1 ounce of the percolate is treated as follows : Evap- 
orate almost to dryness over a water-bath, to dispel spirit ; dis- 
solve the residue in J a fluidounce of diluted sulphuric acid, 
with an equal bulk of water and add 2 fluidrachms of chlo- 
roform ; agitate and warm gently. When the liquors have 
separated, draw off and reject the chloroform ; then add 
to the acid liquor excess of solution of ammonia and 1 
a fluidounce of chloroform ; well agitate, gently warm, and, 
after the liquors have completely separated, transfer the 
chloroform to. a weighed dish, evaporate over a water-bath, 
and dry for one hour at 212° F. (100° C). Allow the res- 
idue of total alkaloid to cool, and then weigh it. Take of 
the percolated liquid as much as shall contain 131 I grains of 
total alkaloid, distil off the spirit, and evaporate over a water- 
bath until the extract weighs two ounces. This extract will 
contain 15 per cent, of total alkaloid. The tincture is pre- 
pared by dissolving 133 grains of the assayed extract in a pint 
of diluted spirit (made by adding enough rectified spirit to 4 
ounces of water to produce a pint of fluid). 1 fluidounce of 
this tincture will contain 1 grain of the alkaloids of nux vom- 
ica. If properly prepared, 10 grains of the extract when 

treated in the following manner should yield li grains of total 
alkaloids. Dissolve the extract in J a fluidounce of water 
with the aid of a gentle heat, and add a drachm of sodium 
carbonate previously dissolved in J a fluidounce of water and 
2 a fluidounce of chloroform ; agitate, warm gently, and sep- 



SUGAR. 701 

arate the chloroform. To the separated chloroform add I a 
fluidounce of diluted sulphuric acid with an equal bulk of 
water ; again agitate, warm, and separate the acid liquid from 
the chloroform. To this acid liquor add now an excess of 
ammonia, and agitate with I a fluidounce of chloroform ; when 
the liquors have separated, transfer the chloroform to a weighed 
dish and evaporate the chloroform over a water-bath. Dry the 
residue for one hour, and weigh. 

SUGAR. 

The qualitative test for sugar by means of an alkaline cop- 
per solution (vide p. 468) may be applied in the estimation of 
sugar in sacchariferous substances. 

Process 1. — 34.65 grammes of pure dry crystals of ordinary 
copper sulphate are dissolved in about 250 cc. of distilled water. 
173 grammes of pure crystals of the double potassium and sodium 
tartrate are dissolved in 480 cc. of solution of caustic soda of 
sp. gr. 1.14. The solutions are only mixed when required, water 
being then added to form 1 litre, smaller quantities of the 
fluids being proportionately diluted. 100 cc. of this mixture 
represent 3.465 grammes of copper sulphate, and correspond to 
0.500 of a gramme of pure anhydrous grape-sugar, 0.475 of 
cane-sugar, 0.807 of maltose, or 0.450 of starch. The solu- 
tions must be preserved in well-stoppered bottles to prevent 
absorption of carbonic acid, and be kept in a dark place. Should 
the mixture give a precipitate on boiling, a little solution of 
soda may be added when making experiments. Such a reagent 
is known as Fehling's solution. 

Dissolve 0.475 of pure dry powdered cane-sugar in about 
50 cc. of water, convert into grape-sugar by acidulating with 
sulphuric acid and heating for an hour or two on a water-bath, 
make slightly alkaline with sodium carbonate, and dilute to 
100 cc. Place 10 cc. of the copper solution in a small flask, 
dilute with three or four times its bulk of water, and gently 
boil. Into the boiling liquid drop the solution of sugar from 
a burette, 1 cc, or less, at a time, until, after standing for the 
precipitate to subside, the supernatant liquid has just lost its 
blue color; 10 cc. of the solution of sugar should be required 
to produce this effect — equivalent to 0.0475 of cane-sugar, 
0.0807 of maltose, or 0.0500 of grape-sugar. Experiments on 
pure cane-sugar must be practised until accuracy is attained ; 
syrups, diabetic urine, and saccharated substances containing 
unknown quantities of sugar may then be analyzed. 

Starch is converted into grape-sugar by gentle ebullition with 
diluted acid for eight or ten hours, the solution being finally 



702 GRAVIMETEIC QUANTITATIVE ANALYSIS. 

diluted so that 1 part of starch, or rather sugar, shall be con- 
tained in about 150 of water. 

If, instead of Fehling's solution, Pavy's ammoniated solution 
be used {Proceedings of the Royal Society of London, vol. xxviii. 
p. 260, and vol. xxix. p. 272 ; or Lancet, March 1, 1884, p. 376 ; 
or Pharmaceutical Journal, 3d Ser., vol. xvii. p. 856), one-fifth 
more of the copper salt will be required to do the same amount 
of work. 

In cases in which loss of blue color cannot be relied on as 
indicating the termination of the reaction, copper suboxide 
should be rapidly filtered out, washed, dried, and, after adding 
the filter-ash, ignited, and the resulting black copper oxide 
weighed. 1 grm. of black oxide (or of suboxide or of metal- 
lic copper) indicates the subjoined amounts of the respective 
sugars : 

One gramme of Glucose. ^ Jg* ™ 

Black oxide . . . .4535 .4308 .6153 .7314 

Suboxide 5042 .4790 .6843 .8132 

Metallic copper . . .5634 .5395 .7707 .9089 

Process 2. — Robert's Method for the Estimation of Sugar in 
Urine. — About 4 ounces of saccharine urine are put into a 
12-ounce bottle, and a lump of German yeast about the size of 
a cob-nut or small walnut is added. This excess of yeast 
hastens fermentation and does no harm. The bottle is then 
covered with a grooved cork (to allow of the escape of carbonic 
acid gas), and set aside in a warm place to ferment. By the 
side of it is placed a tightly-corked 4-ounce phial filled with 
the same urine without any yeast. In about twenty-four hours 
the fermentation will have ceased and the scum cleared off or 
subsided. The fermented urine is then decanted and its spe- 
cific gravity taken. At the same time the specific gravity of 
the unfermented urine in the companion phial is observed. The 
density lost is thus ascertained. Each degree of density lost 
represents a grain of glucose per fluidounce. 

Sugar is often estimated by the measurement of the carbonic 
acid gas evolved or of the alcohol produced during fer- 
mentation. 

Saccharometry.—A generic term for certain quantitative 
operations undertaken with the view of ascertaining the quan- 
tity of sugar present in any matter in which it may be con- 
tained. 

Saccharometry is frequently performed upon common syrup 
(Syrupus, B. P.) and solutions which are known to contain 
nothing but cane- (ordinary) sugar, the object being merely to 



SUGAR. 



703 



ascertain the amount present. In such a case it is only neces- 
sary to take the specific gravity of the liquid at 60° F., and 
then refer to a previously prepared table of densities and per- 
centages. 



Specific 


Sugar, 


Specific 


Sugar, 


Specific 


Sugar, 


gravity. 


•per cent. 


gravity. 


per cent. 


gravity. 


per cent. 


1.007 


is 


1.100 


23.7 


1.210 


46.2 


1.014 


3.5 


1.108 


25.6 


1.221 


48.1 


1.022 


5.2 


1.116 


27.6 


1.231 


50.0 


1.029 


7.0 


1.125 


29.4 


1.242 


52.1 


1.036 


8.7 


1.134 


31.5 


1.252 


54.1 


1.044 


10.4 


1.143 


33.4 


1.261 


56.0 


1.052 


12.4 


1.152 


35.2 


1.275 


58.0 


1.060 


14.4 


1.161 


37.0 


1.286 


60.1 


1.067 


16.3 


1.171 


38.8 


1.298 


62.2 


1.075 


18.2 


1.180 


40.6 


1.309 


64.4 


1.083 


20.8 


1.190 


42.4 


1.321 


66.6? 


1.091 


21.8 


1.199 


44.3 


1.330 ( 


b.p.)66.6? 


e spec. 


grav. may 


be taken 


by a hydrometer, 


technically 


med a 


saccharome 


ter. (The 


above spe 


c. gravs. = 


= 1° to 35° 



Th( 
ten 
Baume.) 

If a liquid contains other substances besides cane-sugar, the 
test of specific gravity is of little or no value. Advantage 
may then be taken of the fact that syrup causes right-handed 
twisting of a ray of plane-polarized light to an extent propor- 
tionate to the amount of sugar in solution. The saccharine 
fluid is placed in a long tube having opaque sides and trans- 
parent ends ; and a ray of homogeneous light, polarized by 
reflection from a black-glass mirror or otherwise, is sent through 
the liquid and optically examined by a plate of tourmaline, 
Nicol's prism, or other polarizing eyepiece. Attached to the 
eyepiece is a short arm which traverses a circle divided into 
degrees. The eyepiece and arm are previously so adjusted that 
when the ray is no longer visible the arm points to the zero of 
the scale of degrees. The saccharine solution, however, so 
twists the ray as to again render it visible ; and the number of 
degrees which the eyepiece has to be rotated before the ray is 
once more invisible is proportionate to the strength of the solu- 
tion. The value of the degrees having been ascertained by 
direct experiment and the results tabulated, a reference to the 
table indicates the, percentage of sugar in the liquid under 
examination. Grape-sugar also possesses the property of 
dextral rotation, but less powerfully than cane-sugar ; more- 
over, the former variety does not, like cane-sugar, suffer inver- 
sion of the direction of rotation on the addition of hydrochloric 
acid to its solution — an operation that furnishes data for ascer- 



704 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

taining the amount of cane- and of grape-sugar, or of crystal- 
lizable and non-crystallizable sugar, present in a mixture. In 
using the polariscope saccharometer it is convenient to employ 
tubes of uniform size and always to operate at the same tem- 
perature. Various modes are adopted of applying for quanti- 
tative purposes this action of syrup on polarized light. 

ALCOHOL. 

Mulder s process for the determination of the amount of alco- 
hol in wine, beers, tinctures, and other alcoholic liquids con- 
taining vegetable matter is as follows : Take the specific gravity 
and temperature of the liquid and measure off a certain quan- 
tity (100 cc.) ; evaporate to one-half or less, avoiding ebullition 
in order that particles of the material may not be carried away 
by the steam. Dilute with water to the original bulk, and 
take the specific gravity at the same temperature as before. 
Of the figures representing the latter specific gravity, all over 
1000 show to what extent dissolved solid matter affected the 
original specific gravity of the liquid. Thus, the specific gravity 
of a sample of wine at 15.5° C. is 0.9951 ; evaporated till all 
alcohol is removed and diluted with water to the original bulk, 
the specific gravity at 15.5° C. is 1.0081. 0.0081 represents the 
gravitating effect of dissolved solid matter in 0.9951 part of 
original wine. 0.0081 subtracted from 0.9951 leaves 0.987, 
which is the specific gravity of the alcohol and water of the 
wine. Or, divide the sp. gr. of the wine by the sp. gr. of the wine 
minus alcohol, carrying out the sum to four places of decimals ; 
the quotient shows the sp. gr. of the water and alcohol only of 
the wine. On referring to a table of the strengths of diluted 
alcohol of different specific gravities, 0.987 at 15.5° C. is found 
to indicate a spirit containing 8 per cent, of real alcohol. 
Mulder's process is that adopted officially (U. S. P.) for ascer- 
taining the strength of white wine ( Vinum Album) and red 
wine ( Vinum Rubrum). If the foregoing operation be con- 
ducted in a retort, the liquid being boiled and the steam care- 
fully condensed, the distillate, diluted with water to the original 
bulk of wine operated on, will still more accurately represent 
the amount of water and alcohol in the wine — its specific gravity 
showing the percentage of real alcohol present. 



DIALYSIS. 

Dialysis (from dtd, dia, through, and hjrrts, hisis, a loosing or 
resolving) is a term applied by Graham to a process of analysis 



DIALYSIS. 705 

by diffusion through a septum. The apparatus used in the 
process is called a dialyzer, and is constructed and employed in 
the following manner. The most convenient septum is the 
commercial article known as parchment-paper, made by immers- 
ing unsized paper for a short time in sulphuric acid ; it is sold 
by most dealers in chemical apparatus. A piece of this material 
is stretched over a gutta-percha hoop, and secured by a second 
external hoop. Dialyzers of useful size are one or two inches 
deep and five to ten inches wide. Liquids to be dialyzed are 
poured into the dialyzer, which is then floated in a flat dish 
containing distilled water. The portion passing through the 
septum is termed the diffusate, the portion which does not pass 
through is termed the dialysate. 

The practical value of dialysis depends upon the fact that 
certain substances will diffuse through a given septum far 
more rapidly than others. Uncrystallizable bodies diffuse very 
slowly. Of such matters as starch, gum, albumen, and gelatin, 
the last named is perhaps least diffusive ; hence substances of 
this class are termed colloids, or bodies like coffin, which is the 
soluble form of gelatin. Substances which diffuse rapidly are 
mostly crystalline ; hence bodies of this class are termed crystal- 
loid. 

Solution of dialyzed iron, Liquor Ferri Dialysatus, B. P., an 
aqueous solution of about 5 per cent, of highly basic ferric oxy- 
chloride, is obtained by saturating 1 fluidounce of the solution 
of ferric perchloride with fresh ferric hydrate (obtained by pre- 
cipitating 6 fluidounces of the same solution by ammonia, and 
washing and draining the product), filtering if necessary, pla- 
cing on a dialyzer floating in distilled water, and displacing the 
fluid in the dish by water daily for a week or two, or until the 
diffusate gives no reaction with silver nitrate, and the fluid on 
the dialyzer is almost tasteless. The colloid fluid which has 
thus been subjected to dialysis (hence the only title to the 
name dialyzed iron), and which does not pass through the 
dialyzer, is the highly basic ferric oxychloride, or so-called 
" dialyzed iron,' 1 or " dialytic iron." This fluid has very little 
taste of iron. Its value as a medicine has been questioned, its 
non-diffusibility suggesting that it never passes out of the in- 
testinal canal, and therefore never gets into the blood. Possibly 
it becomes decomposed in the system and the resulting product 
becomes assimilated. 

It is " a clear dark reddish-brown liquid, free from any 
marked ferruginous taste." Neutral to test-papers. Specific 
gravity about 1.047. The solution gives no precipitate with 
potassium ferrocyanide or with silver nitrate > but after being 



706 GRAVIMETRIC QUANTITATIVE ANALYSIS. 

heated with hydrochloric acid it yields with potassium ferro- 
cyanide a blue precipitate. 100 grains by weight afford a pre- 
cipitate with solution of ammonia, which, washed, dried, and 
ignited, weighs 5 grains. 

The phenomena of dialysis show that crystalloids are supe- 
rior to colloids in affinity for water. 



QUESTIONS AND EXERCISES. 

Potassium carbonate is said to lose 16 per cent, of water on exposure 
to a red heat ; give the details of manipulation observed in verifying this 
statement.— Write a few paragraphs descriptive of the process of ultimate 
organic analysis.— In what forms are carbon, hydrogen, and nitrogen 
weighed in quantitative analysis?— In the combustion of .41 of a gramme 
of sugar, what weights of products will be obtained ? Ans. .632 of car- 
bonic acid gas (C0 2 ) and .237 of water (H 2 0).— How is cinchona assayed 
for mixed alkaloids ?— Give the official method for the estimation of mor- 
phine in opium.— Mention the operations necessary for the estimation of 
the proportion of sugar in saccharated ferrous carbonate or in a speci- 
men of diabetic urine.— What is understood by saccharometry ?— Give 
two processes for the estimation of the percentage of alcohol in tinc- 
tures, wines, or beer. — Define dialysis. 



CONCLUSION. 



Detailed instructions for the quantitative analysis of potable 
water, articles of food, general technical products, special min- 
erals, soils, manures, air, illuminating agents (including solid 
fats, oils, spirits, petroleum, and gas), dyes, and tanning- 
materials, would scarcely be in place in this volume. 

The course through which the reader has been conducted 
will, it is hoped, have taught him the principles of the science 
of chemistry, and given him special knowledge concerning the 
applications of that science to medicine and pharmacy, as well 
as have imparted sufficient manipulative skill to meet the 
requirements of manufacture or analysis. The author would 
venture to suggest that this knowledge be utilized, not only in 
the way of personal advantage, but in experimental researches 
on chemical subjects connected with pharmacognosy, pharma- 
cology, therapeutics, and pharmacy. The discovery and publi- 
cation of a new truth, great or small, is the best means where- 
by to aid in advancing the calling in which we may be engaged, 
increase our own reputation, and contribute to that " ultimate 
end of knowledge " which Bacon described as " employing the 
divine gift of reason to the use and benefit of mankind." 



APPENDIX 



TABLE OF TESTS FOR IMPURITIES IN PREPARATIONS 
OF THE UNITED STATES PHARMACOPCEIA* 



Name of Preparation. 


Impurities. 


Tests. 


Page 


Acacia, 


Starch. 


Iodine. 


473 




Mineral matter. 


Incineration. 


102 


Acetanilidum, 


Other organic matter. 


Sulphuric acid (colored). 






Aniline, etc. 


Ferric chloride. 


431 




Copper. 


Ammonia in excess. 


193 




Lead, copper, etc. 


Sulphuretted hydrogen. 


268 




Sulphuric acid. 


Soluble barium salt. 


310 


Acidum Aceticum 


Hydrochloric acid. 


Silver nitrate. 


268 


and Acidum Acet- ■ 


Sulphurous and ferric 


Ammonia and silver ni- 




icum Glaciate, 


acid. 


trate (darkened). 






Empyreumatic sub- 


Vol. sol. of potassium per- 






stances. 


manganate. 


652 




Mineral matter. 


Evaporation and ignition. 


102 


' 


Metallic impurities. 


Hydrochloric acid. 


221 




Sulphides, etc. 


In ammonia (soluble). 




Acidum Arsenosum, - 


Mineral matter. 


Evaporation and ignition. 


102 




Antimony, tin, and cad- 


Hydrogen sulphide precip- 




. 


mium. 


itate in Na 2 C0 3 (sohible). 




f 


Cinnamic acid. 


Potassium permanganate. 


652 




Mineral matter. 


Incineration. 


102 


Acidum Benzoicum, ■> 


Carbonizable organic 

matter. 
Chlorine. 


Sulphuric acid (color). 




■ 


Silver nitrate. 


268 




Sulphuric acid. 
Hydrochloric acid. 


Barium chloride. 


310 




Silver nitrate. 


268 




Pb, Cu, Fe, etc. 


Ammonium sulphide. 


258 


Acidum Boricum, 


Calcium salts. 


Ammonium oxalate. 


117 




Magnesium salts. 


Sodium phosphate. 


122 




Ammonium salts. 


Heat with potash. 


98 




Sodium salts. 


Flame test. 


89 




Mineral matter. 


Incineration. 


102 


Acidum Carbolicum, ■{ 


Creasote and cresylic 


Glycerin and dilute (tur- 




I 


acid. 


bidity). 


453 


Acidum Chromicum, 


Sulphuric acid. 


Barium chloride. 


310 


\ 


Tartaric and oxalic acids. 


Potassium acetate. 


322 


Calcium salts. 


Ammonia and ammonium 




Acidum Citricum, «j 


Copper, lead, etc. 
Sulphuric acid. 


oxalate. 
Sulphuretted hydrogen. 


117 
258 




Barium chloride. 


310 


(^ 


Mineral matter. 


Incineration. 


102 


Acidum Gallicum, J 


Tannic acid. 


(Isinglass), gelatin. 


358 


| 


Mineral matter. 


Incineration. 


102 


Acidum Hydrobro- f 


Iodine. 


Cl-water and chloroform. 


270 


micum Dilutum, \ 


Sulphuric acid. 


Barium chloride. 


310 



* The manipulations necessary to be observed in testing for impurities will be 
found described in the paragraphs treating of those substances. The table also 
includes references to processes for ascertaining deficiency in strength of official 
articles. 

The other characters and tests of pharmacopoeial chemical compounds have been 
given in connection with the respective synthetical and analytical reactions. 

707 



708 



APPENDIX. 



Table of Tests — Continued. 



Name of Preparation. 


Impurities. 


Tests. 


Page, 




Fixed matter. 


Evaporation. 


102 


Acidum Hydrobro- ! 
micum Dilutum, 


Acids. 


Color on standing. 




General. 


Quantitative analysis. 


637 




Arsenum. 


Bettendorffs test. 


175 




Iodine and bromine. 


Chloroform and Cl-water. 


270 




Sulphurous acid. 


4 drops of I solution (tur- 




Acidum Hydrochlo- 
ricum, 


Sulphuric acid. 


bidity). 
Barium chloride. 


310 




Thallium, lead, etc. 


Sulphuretted hydrogen. 


258 


1 


Copper. 


Ammonia in excess. 


193 


I 


Arsenum. 


Bettehdorff s test. 


175 


Acidum Hydrocya- 


Fixed matter. 


Evaporation. 


102 


nicum Dilutum, 








' 


Lead, etc. 


Sulphuretted hydrogen. 


258 


Acidum Hypophos- 
phorosum Dilutum, ' 


Calcium salts. 


Ammonium oxalate. 


117 


Sulphuric, tartaric acids, 
etc. 


Barium chloride. 


310 




Potassium. 


Platinic chloride. 


78 




Sulphates. 


Barium chloride. 


310 




Chlorides. 


Silver nitrate. 


268 




Copper, iron, lead, etc. 


Ammonium sulphide and 








ammonia. 


224 


Acidum Lacticum, ■{ 


Sugars. 


Fehling's solution. 


468 




Glycerin. 


Zinc carbonate and alco- 








hol. 


458 




Organic impurities. 


Concentrated sulphuric 

acid (color). 
Ammonia in excess. 






Copper. 


193 




Lead, iron, etc. 


Ammonia and ammonium 








sulphide. 


224 


Acidum Nitricum, 


Sulphuric acid. 
Hydrochloric acid. 


Barium chloride. 


310 




Silver nitrate. 


268 




Iodine and bromine. 


Shake with chloroform. 


271 




Iodic and bromic acids. 


Zinc and chloroform (re- 








duction). 


460 




Fixed oils. 


Mix with alcohol (no oily 




Acidum Oleicum, 


Palmitic and stearic 


drops). 
Lead salt, insoluble in 


460 




acids. 


ether. 


460 




Phosphorous acid. 


Mercuric chloride (turbid). 






Arsenum. 


Bettendorffs reaction. 


175 




Phosphate. 


Add alcohol and ether 




Acidum Phosphori- _ 




(turbidity). 




cum, 


Sulphuric acid. 
Hydrochloric acid. 


Barium chloride. 


310 




Silver nitrate. 


268 




Pyro- and meta-phos- 


Ferric chloride. 


331 




phoric acid. 






. 


Iron, carbolic acid, and 
coloring-matter. 


Crystallized from alcohol. 


492 


Acidum Salicylicum, - 


Organic. 


Concentrated sulphuric 
acid (colored). 






Hydrochloric acid. 


Silver nitrate. 


268 




Lead. 


Excess of alcohol (ppt.). 






Nitric and nitrous acid. 


Ferrous sulphate and sul- 








phuric acid. 


289 


Acidum Sulphuri- J 


Hydrochloric acid. 


Silver nitrate. 


268 


cum, 


Lead, arsenic, copper, 

etc. 
Iron, etc. 


Hydrogen sulphide. 


258 




Ammonia and ammonium 




«. 




sulphide. 


224 


Acidum Sulphuro- 


Sulphuric acid. 


Barium chloride. 


310 


sum, 

f 


Gum and dextrin. 


Dilute solution with alco- 




Acidum Tannicum, -j 


Resin. 

1 


hol (turbidity). 
Dilute with water (turbid- 
ity). 





APPENDIX. 



709 



Table of Tests — Continued. 



Name of Preparation. 


Impurities. 


Tests. 


Page. 


[ 

Acidum Tartaricum, ■{ 


Oxalic and uric acids. 


Calcium sulphate. 


316 


Sulphuric acid. 
Calcium salts. 


Barium chloride. 
Ammonium oxalate. 


310 
117 


I 


Iron, lead, copper, etc. 


Ammonium sulphide. 


224 


Adeps, J 


Alkalies. 


Red litmus. 


96 


Starch. 


Iodine. 


473 


Chlorides. 


Silver nitrate. 


268 


i 


Free fatty acids. 


.2 cc. standard KOH solu- 




I 




tion. 


637 


f 


Glycerin. 


Evaporation. 


461 


Adeps Lanse Hydro- j 
sus, J 


Alkalies. 


Red litmus. 


96 


Free fatty acid. 


Drop of KOH solution. 


637 


I 


Ash. 


Incineration. 


102 


( 


Residue. 


Evaporation. 


460 


JElher, < 


Aldehyde. 


Potassium iodide. 


449 


I 


Alcohol and water. 


Water. 


449 


f 


Amylic alcohol. 


Evaporation on blotting- 




JEther Aceticus, ■{ 




paper (odor). 




Alcohol. 


Water. 


449 


1 

I 
f 


Organic. 


Concentrated sulphuric 

acid (color). 
Evaporation on blotting- 




Fusel oil. 




Alcohol, \ 




paper (odor). 




Aldehyde, methyl alco- 
hol, and oak tannin. 


Potassium-hydrate s o 1 u - 




1 


tion (color). 




I 


Organic. 


Silver nitrate (color). 




f 


Copper, lead, and zinc. 


Hydrogen sulphide. 
Potassium hydrate. 


258 


Jit6mew, -j 


Ammonium. 


98 


Iron. 


Potassium ferro- or ferri- 




L 




cyanide. 


161 


f 


Iron. 


Potassium ferrocyanide. 


162 


Alumini Hydras, < 


Sulphate. 


Barium chloride." 


310 


I 


Zinc and lead. 


Hydrogen sulphide. 


258 




Free acid. 


Standard sodium hyposul- 




1 




phite. 


655 


Alumini Sulphas, ■{ 


Iron. 


Potassium ferrocyanide. 


162 


1 


Ammonium salts. 


Potassium hydrate. 


98 


I 


Copper, lead, or zinc. 


Hydrogen sulphide. 


258 


f 


Sulphate. 


Barium chloride. 


310 


Ammonii Benzoas, < 


Chloride. 


Silver nitrate. 


268 


\ 


Fixed salts. 


Non-volatility. 


99 


f 


Bromates. 


Dilute sulphuric acid. 


271 


Ammonii Bromi- J 


Metals. 


Hydrogen sulphide. 


258 


Sulphates. 
Iron. 


Barium chloride. 


310 


L 


Potassium ferrocyanide. 


162 


f 


Sulphates. 


Barium chloride. 


310 


1 


Metals. 


Sulphuretted hydrogen. 


258 


Ammonii Carbonas, ■{ 


Calcium. 


Ammonium oxalate. 


117 


\ 


Chloride. 


Silver nitrate. 


268 


I 


Non-volatile matters. 


Evaporation. 


102 


( 


Metals. 


Hydrogen sulphide. 


258 




Sulphate. 


Barium chloride. 


310 


. 


Calcium. 


Ammonium oxalate. 


117 


Ammonii Chlori- J 


Barium. 


Dilute sulphuric acid. 


103 


Sulphocyanate. 


Ferric chloride. 


162 




Iron. 


Potassium ferrocyanide. 


162 




Non-volatile matter. 


Evaporation and ignition. 


102 




Sulphate. 
Iodine (free). 
Chloride or bromide. 


Barium chloride. 


310 


Ammonii Iodidum, • 


Starch. 

Standard silver nitrate. 


473 
641 


. 


Iron. 


Potassium ferrocyanide. 


162 


Ammonii Nitras, j 


Sulphate. 


Barium chloride. 


310 


Chloride. 


Silver nitrate. 


268 


Ammonii Valeri- J 


Acetate. 


Ferric chloride (deep 
color). 




cmas, J 


Sulphate. 


Barium chloride. 


310 



SI 



710 



APPENDIX. 



Table of Tests — Continued. 



Name of Preparation. 1 Impurities. 


Tests. 


Page. 


Ammonii Valerianas, Chloride. 


Silver nitrate. 


268 


(Aldehyde. 


Potassium hydrate(brovvn). 
Fractional distillation. 




Amyl Nitris, ^General. 


407 


(Free acid. 


Quantitative analysis. 


678 


Amylum, |Ash. 


Incineration. 


102 




Sulphate. 


Barium chloride. 


310 




Calcium. 


Ammonium oxalate. 


117 


Antimonii et Potas- 
sii Tartras, 


Chloride. 
Potassium bitartrate. 


Silver nitrate. 

Sodium carbonate (no 


268 


I 


effervescence). 






Iron and other metals. 


Potassium ferrocyanide. 


162 




Arsenum. 


Bettendorff s test. 


175 


r 


Chloride. 


Silver nitrate. 


268 


| 


Iron and other metals. 


Potassium ferrocyanide. 


162 


Antimonii Oxidum, <! 


Sulphate. 


Barium chloride." 


310 


Copper and lead. 


Ammonium sulphide. 


258 


1 


Arsenum. 


Bettendorff s test. 


175 


Antimonii Sulphi- ;General. 


Quantitative analysis. 


671 


dum, 

Antimonium Sul- J 
phuratum, 


Chloride. 
Calcium. 


Silver nitrate. 
Ammonium oxalate. 


268 
117 


Sulphate. 


Barium chloride. 


310 




Soluble salts. 


Evaporation. 


102 




Metallic impurities. j 


Ammonium sulphide. 
Hydrogen sulphide. 


224 
258 




Ammonia. 


Mercuric chloride (color). 






Sulphates. 


Barium chloride. 


310 


Aqua, 


Chlorides. 


Silver nitrate. 


268 




Nitrates. 


Diphenylamine and sul- 
phuric acid (ring). 






Nitrites. 


Zinc, iodide, starch (blue). 






Organic matter. 


Potassium permanganate 








standard solution. 


652 




Calcium. 


Ammonium oxalate. 


117 




Metallic. 


Hydrogen sulphide. 


258 


Aqua Ammonise, 


Sulphates. 


Barium chloride. 


310 




Fixed matter. 


Evaporation and ignition. 


102 


Aqua Chlori, 


Hydrochloric acid. 


Blue litmus. 


96 


{ 


Sulphates. 


Barium chloride. 


310 




Calcium. 


Ammonium oxalate. 


117 




Chlorides. 


Silver nitrate. 


268 




Ammonia. 


Nessler's reagent. 


639 


Aqua Destillata, 


Carbonic acid. 


Lime-water. 


314 




Organic matter. 


Potassium permanganate. 


652 




Nitrates. 


Diphenylamine and sul- 
phuric acid (ring). 






Nitrites. 


Zinc, iodide, starch (blue). 




Aqua Hydrogenii f 
Dioxidi, 1 


Hydrofluoric acid. 


Sulphuric acid. 


342 


Barium. 


Dilute sulphuric acid. 


103 




Copper. 
Lead. 


Ammonia in excess. 


193 


Argenti Nitras, -J 


Dilute sulphuric acid. 


215 


Argenti Oxidum, -\ 


Carbonate. 


Effervescence with nitric- 






acid. 


219 


General. 


Quantitative analysis. 


676 


Arseni Iodidum, 


Fixed salts. 


Incineration. 


102 


r 


Organic. 


Sulphuric acid to solu- 




Atropina, \ 




tion (color). 




Morphine. 


Sulphuric acid to dry sub- 




Balsamum Peruvi- [ 




stance (color). 


519 


Essential oil. 


Dilute with water. 


414 


anum, I 








f 


Heavy hydrocarbons. 


Evaporation. 


102 


Sulphur "comps. 


Silver nitrate and ammo- 




Benzinum, \ 




nia (brown). 




I 


Benzol. 


Nitric and sulphuric acids, 




i 




warm. 


430 



APPENDIX. 



711 



Table of Tests — Continued. 




712 



APPENDIX. 



Table of Tests — Continued. 



Name of Preparation. 


Impurities. 


Tests. 


Page. 




( 


Paraffin. 


Completely soluble in con- 




Cera Flava, 


1 


Tallow and other fats. 


centrated sulphuric acid. 
Ignited, smell of acrolein. 






f 


Carbonate. 


Effervescence with acids. 


314 


Cerii Oxalas, 


i 


Arsenum, etc. 


Hydrogen sulphide. 


258 


Aluminium. 


Potassium hydrate. 


163 




1 


Zinc. 


Ammonium sulphide. 


136 




[ 


Hydrochloric acid and 


Silver nitrate. 


268 


Chloral, 


\ 


chlorides. 
Chloral alcoholate. 


Iodoform test. 


444 




General. 


Quantitative analysis. 


487 




Chlorides. 1 


Shake with f Silver 
water and test I nitrate, 
the watery so- j Starch 
lution. [ andKI. 






1 


i 
Free chlorine. 


268 








Chloroformum, 


<; 


J 


473 




1 


General. 


Specific gravity. 


401 






Non-volatile matter. 


Residue on evaporation. 


401 




i 


Hydrocarbons. 


Sulphuric acid. 


401 




r 


Organic matter. 


Colors with sulphuric acid. 


526 


Cinchonidine Sul 
phas, 


i 


Excess of water. 


Dried at 100° C. 


660 


I 


Cinchonine. 


Ammonia after tartrate, 
etc. 


526 




I 


Mineral matter. 


Incineration. 


102 


Cinchonina, 


{ 


Organic matter. 


Colors with sulphuric acid. 


526 


Mineral matter. 


Incineration. 


102 




( 


Excess of water. 


Dried at 100° C. 


660 


Cinchoninse Sulphas 


i 


Cinchonidine. 


Insoluble in chloroform. 


526 




\ 


Organic. 


Color sulphuric acid. 


526 






Water of crystallization. 


Heat at 100° C. 


660 


Cocainse Hydrochlo- 


J 


Non-volatile matter. 


Incineration. 


102 


ras, 


i 


Coca bases. 


1 drop of potassium per- 






I 




manganate gives a color. 


652 


Coccus, 




Mineral matter. 


More than 5 per cent, of 
ash. 


102 


Codeina, 


{ 


Morphine. 
Non-volatile matter. 


Nitric acid on the solid. 
Incineration. 


519 
102 




f 

i 


Fixed oils. 


Soft residue on evapora- 
tion. 


425 


Copaiba, 


\ 

i 


Turpentine. 


Odor during evaporation. 


425 


Gurjun balsam. 


Carbon disulphide and 






I 




nitric and sulphuric 






1 




acids (violet). 






f 




Oxidation. 


453 


Creasotum, 




Carbolic acid. 


Non-volatility at 100° C. 
Crystallization on cooling. 


453 
453 




| 

i 


Magnesium. 


Sodium phosphate. 


122 


Creta Prxparata, 


Iron. 


Potassium ferrocyanide. 


161 


Sulphate. 


Barium chloride. 


310 




[ 


Barium. 


Dilute sulphuric acid. 


103 




( 


Coal-tar colors. 


No color given to benzin. 




Crocus, 


1 


Inorganic matter. 


Incineration, not more 
than 7.5 per cent, of ash. 


102 




( 


Iron, aluminium, etc. 


Ammonia. 


161 


Cupri Sulphas, 


1 


Arsenum, lead, zinc, etc. 


Hydrogen sulphide and 
- acetic acid. 


258 


Elaterinum, 




Non-volatile matter. 


Incineration. 


102 


Eucalyptol, 




Phenols. 


Ferric chloride. 


454 


Ferri Carbonas Sac- 


{ 


Sulphate. 


Barium chloride. 


310 


charatus, 


General. 


Quantitative analysis. 


650 


Ferri et Aramonh 
Citras, 


{ 


Citrates and tartrates 
of potassium and so- 
dium. 


Alkalinity of ash. 


96 


Ferri et Ammonit 

Sulphas, 
Ferri et Ammonii 


1 

{ 


Aluminium. 


Potash, acid, ammonia. 


141 


Citrates and tartrates of 


Alkalinity of ash. 


96 


Tartras, 


fixed alkalies. 







APPENDIX. 



713 



Table of Tests — Continued. 







714 



APPENDIX. 



Table of Tests — Continued. 



Name of Preparation. 



Impurities. 



Tests. 



Page. 



Hydrarg. Subsul. 
Flavus, 

Hydrargyrum, 



Hydrargyrum Am- 
moniatum, 



Hydrarg. cum Creta, 

Hydrastininx Hy- 

drochloras, 
Hyoscinx Hydro- 

bromas, 
Hyoscyaminse Hy- 

drobromas. 



Iodoformum, 



Iodum, 

Jalapa, 

Limonis Succus, 

Linum, 

Liquor Ammonii 

Acetatis, . 
Liquor Calcis, 



Liquor Ferri Aceta- 
tis, IAquor Ferri 
Chloridi, Liquor 
Ferri Citratis, 



Liquor Ferri Ni- 

tratis, 
Liq. Fer. Subsulphas, 

Liq. Fer. Tersul- 

phatis, 
Liq. Hydrargyri 

Nitratis, 
Liq. Plumbi Sub- 

acetatis, 
Liquor Potassx and 

Liquor Sodse, 
Liq. Sodse Chloratx, 



IJthii Benzoas, 



Mercurous and lead salts. 

Fixed salts. 
Foreign metals. 

Fixed matter. 

Carbonate. 

Mercurous 



Lead. 

Fixed salts. 
General. 

Mercurous oxide. 
Mercuric oxide. 
Inorganic matter. 

Non- volatile matter. 

Other alkaloids. 

Fixed matter. 

Free acid. ^| 

Coloring matter. > 

Iodide, soluble. ) 

General. 

Fixed salts. 

Iodine cyanide. 

Jalap. 

Ash. 

Deficiency of citric acid 

Starch. 

Non- volatile matter. 

Deficiency in strength. 
Ferrous salts. 
Zinc, copper, etc. 

Nitric acid. 

General impurity or f 
deficiency. \ 

General. 

Nitric acid. 
Ferrous salt. 

Mercurous salts. 
Fixed salts. 
General. 
Deficiency. 
General. 

General. 

Chloride. 

Sulphate. 

Arsenic, lead, iron, etc. 

Calcium. 

Potassium. 

General. 

Calcium. 

Arsenum, lead, etc. 



Lithii Bromidum, 



I [Sulphate. 



! Iron, aluminium, etc. 
1 j Potassium. 
I I Iodide. 
( I General. 



Not soluble in hydrochlo- 
ric acid. 

Non-volatility. 

Yellowish color with 
NaS 2 3 . 

Non-volatility. 

Effervescence with acids. 

Not soluble in hydrochlo- 
ric acid. 

Dilute sulphuric acid. 

Non- volatility. 

Quantitative analysis. 

Hydrochloric acid. 

Hydrogen sulphide. 

Incineration. 

Incineration. 

Platinic chloride (ppt.). 

Incineration. 

Shake (Litmus, 
with < Colored. 

water. (Silver nitrate. 

Quantitative analysis 

Non-volatility. 

Physical characters. 

Solubility of resin. 

Incineration ; .5 per cent. 

Quantitative analysis. 

Iodine. 

Evaporation and incinera- 
tion. 

Quantitative analysis. 

Potassium ferricyanide. 

Hydrogen sulphide, am- 
monia. 

Ferrous sulphate and sul- 
phuric acid. 

Specific gravity. 

Quantitative analysis. 

Quantitative analysis. 

Ferrous sulphate, etc. 
Potassium ferricyanide. 

Hydrochloric acid. 
Non-volatility. 
Quantitative analysis. 
Specific gravity. 
Quantitative analysis. 

Quantitative analysis. 
Silver nitrate. 
Barium chloride. 
Ammonium sulphide. 
Ammonium oxalate. 
Sodium cobaltic nitrite. 
Quantitative analysis. 
Ammonium oxalate. 
Hydrogen sulphide. 
Barium chloride. 
Ammonium sulphide. 
Sodium cobaltic nitrite. 
Chlorine-water and starch. 
Quantitative analysis. 



APPENDIX. 



715 



Table of Tests — Continued. 



Name of Preparation. 


Impurities. 


Tests. 


Page. 


Lithii Bromidim, 


Chloride. 


Silver nitrate. 


268 


' 


Arsenic, lead, etc. 


Hydrogen sulphide. 


190 




Iron, aluminium, etc. 


Ammonium sulphide. 


190 


Lithii Carbonas and t 
Lithii Citras, 


Chloride. 
Potassium. 


Silver nitrate. 

Sodium cobaltic nitrite. 


268 
80 


Sulphate. 


Barium chloride. 


310 




General. 


Quantitative analysis. 


6:34 




Calcium. 


Ammonium oxalate. 


117 


f 


Carbonate. 


Effervescence with acids. 


314 


1 


Sulphate. 


Barium chloride. 


310 


. 1 


Organic. 


Sulphuric acid (color). 




Lithii Salicylas, \ 


Chloride. 


Silver nitrate. 


268 


Calcium. 


Ammonium oxalate. 


117 


I 


Aluminium, etc. 


Ammonium sulphide. 


190 


1 


Potassium. 


Sodium cobaltic nitrite. 


80 


I 


General. 


Quantitative analysis. 


634 


( 


More than 10 per cent. 


Incineration. 


427 


Lupulinum, < 


of ash. 






\ 


Sand, etc. 


Insoluble in water. 






Starch. 


Microscope 


474 


Lycopodium, 


More than 5 per cent, of 
mineral matter. 


Incineration. 


102 




Carbonate. 


Effervescence with acids. 


314 




Sulphate. 


Barium chloride. 


310 




Chloride. 


Silver nitrate. 


268 


Magnesia, 


Metallic. 


Ammonium sulphide. 


256 




Water, more than 5 per 


Ignition and weigh. 


102 




cent. 








General. 


Quantitative analysis. 


666 




Calcium. 


Ammonium oxalate. 


117 


Magnesii Carbonas, - 


Sulphate. 
Chloride. 


Barium chloride. 
Silver nitrate. 


310 
268 


' 


Metallic. 


Ammonium sulphide. 


256 




Sodium. 


Flame. 


90 


Magnesii Sulphas, ■ 


Metallic. 
Chloride. 


Ammonium sulphide. 
Silver nitrate. 


256 
268 


Arsenum. 


Bettendorff s test. 


175 


Antimony. 


Ammonium sulphide. 


184 


Mangani Dioxidum, < 


Organic. 
Sulphides. 


No loss on ignition. 
Acids. 


102 
304 




General. 


Quantitative analysis. 


667 




Iron. 


Potassium sulphocyanate. 


162 




Arsenum and copper. 


Hydrogen sulphide'. 


190 




Zinc. 


Hydrogen sulphide and 




Mangani Sidphas, -j 


Magnesium and alkalies. 


acetic acid. 
No residue after precip- 
itating with ammonium 
carbonate. 


256 




General. 


Quantitative analysis. 


666 


r 


Chlorides. 


Silver nitrate. 


268 


1 


Starch. 


Iodine. 


473 


Mel, -1 


Sulphates. 


Barium chloride. 


310 


[ 


Glucose and inorganic 


.2 per cent, of ash on in- 




matter. 


cineration. 


102 




Thymol. 


Sulphuric and nitric acids 

(blue). 
Non-volatility on water- 




Menthol, 


Wax, paraffin, and inor- 






ganic matter. 


bath. 


112 


Methyl Salicylas, 


Alcohol, chloroform. 


Distil. 


127 




Narcotine, etc. 


Concentrated sulphuric 
acid (yellow). 




Morphina, Mor- 


Strychnine. 


Cone, sulph. acid and pot. 




phinse Acetas, and - 




bichromate (purple). 




Morphinse Sulphas, 


Codeine, etc. 


Soluble in ether. 






Mineral matter. 


Incineration. 


102 


I 


General. 


Quantitative analysis. 


699 



716 



APPENDIX. 



Table of Tests — Continued. 



Name of Preparation. 


Impurities. 


Tests. 


Page. 


( 


Mineral matter. 


Incineration. 


102 


Naphtalinum, < 


Coal-tar contaminations. 


Sulphuric acid (concen- 
trated) (dark red). 




{ 


Mineral matter. 


Incineration. 


102] 


! 
Naphtol, -j 


Naphtalin. 


Insoluble in water. 


434 


Organic. 


Solution in water. 


434 


I 


a-naphtol. 


Sulphuric acid. 


434. 


Olea* 








Opium, 


Deficiency in morphine. 


Quantitative analysis. 


698 




General. 


Melting- and boiling-point. 


485 




Sulphate. 


Barium chloride. 


310 




Chloride. 


Silver nitrate. 


268 




Amylic alcohol. 


Opalescent solution with 




Paraldehydum, 




water. 


636 




Free acid. 


Standard potassium hy- 
drate. 






Fixed impurities. 


Non-volatility on water- 








bath. 


112 


Pepsinum, 


Alkaline. 


Litmus. 


96 


General. 


Quantitative analysis. 


550 


Petrolatum Liqui- 


Resins, fats, and fixed 

oils. 
Organic. 

Fixed matter. 


Sulphuric acid, oily drops. 




dum, Petrolatum J 
Molle, and Petro- j 
latum Spissitm, 


Concentrated sulphuric 

acid (black). 
Incineration in platinum. 


102 


Phosphorus, 


Arsenum. 


Hydrogen sulphide. 


190 


Sulphur. 


Barium chloride. 


310 


Physostigminse Salt- ( 








cylas, Physostig- < 


Fixed salts. 


Incineration. 


102 


minx Sulphas, (. 








( 


Alkaloids. 


Mercuric chloride, platinic 




Picrotoxinum, < 




chloride, tannin. 


571 


\ 


Fixed salts. 


Incineration. 


102 


Pilocarpine Hydro- j 
chloras, \ 
Piper inum, 


Fixed salts. 


Incineration. 


102 


Fixed salts. 


Incineration. 


102 


f 


General. 


Quantitative analysis. 


631 




Carbonate. 


Opalescent solution in 




Plumb i Acetas, -j 




water. 




1 


Iron and zinc. 


Hydrogen sulphide and 




I 




ammonia. 


256 


f 


Insoluble matter. 


Not completely soluble in 




Plumbi Carbonas, ■{ 


Other elements. 


nitric acid. 
Residue after precipitating 
Pb with H 2 S. 




i 








Nitrate. 


Sulphuric acid and indigo. 


291 


Plumbi Iodidum, \ 


Acetate. 
Soluble salts. 


Ferric chloride. 

Solution evaporated, resi- 


300 


I 




due left. 


102 


[ 


Iron and copper. 


Potassium ferrocyanide 




Plumbi Nitras, < 




(colored ppt.). 




\ 


Zinc, etc. 


Ammonium sulphide. 


162 




i Carbonate. 


Effervescence with acid. 


314 




More than 2 per cent, of 


Heat strongly and weigh. 


102 




moisture. 






Plumbi Oxidum, 


Copper. 


Ammonia. 


193 




Iron. 


Ammonia. 


161 




Silicate, barium sul- 


Not completely soluble in 




. 


phate. 


HN0 3 . 


355 


f 
Potassa, ■{ 

{ 


Organic matter. 


Not clear solution in water. 




Arsenum, lead, etc. 


Hydrogen sulphides. 


222 


Ilron, aluminium, etc. 


Ammonia. 


165 


Calcium. 


Ammonim oxalate. 


117 



* The tests for the respective oils do not admit of arrangement in tabular form. 
The student is therefore referred to the text of this Manual or to the Pharma- 
copoeia itself. 



APPENDIX. 



717 



Table of Tests — Continued. 



Name of Preparation. 


Impurities. 


Tests. 




Chloride. 


Silver nitrate. 




Sulphate. 


Barium cbloride. 


Potassa, 


General. 


Quantitative analysis. 


Carbonate. 


Effervescence with acids. 




Nitrate. 


Sulphuric acid and indigo. 




Silica. 


Add an acid. 




Arsenum. 


Odor on heating. 




Lead, etc. 


Hydrogen sulphide. 




Sulphate. 


Barium chloride. 


Potassii Acetas, 


Chloride. 


Silver nitrate. 




Iron, etc. 


Ammonium sulphide. 




Carbonates. 


Effervescence with acids. 




Organic. 


Sulphuric acid (colored). 




Carbonate. 


Pbenolphtalein. 


Potassii Bicarboqas, - 


Metallic. 
Iron. 


Hydrogen sulphide. 
Potassium ferrocyanide. 


• 


Chloride. 


Silver nitrate. 


Chloride. 


Silver nitrate. 




Sulphate. 


Barium chloride. 


Potassii Bitartras, • 


Insoluble matter. 


Not soluble in ammonia. 




Calcium. 


Ammonium oxalate. 




Copper, lead, etc. 
Sodium. 


Ammonium sulphide. 




Flame test. 




Bromate. 


Color with dilute acids. 




Iodine. 


Chlorine-water and starch. 




Aluminium, etc. 


Ammonium sulphide. 




Arsenum, etc. 


Hydrogen sulphide. 


Potassii Bromidum, • 


General. 


Quantitative analysis. 




Calcium. 


Ammonium oxalate. 




Barium. 


Potassium sulphate. 




Sulphate. 


Barium chloride. 




Iron. 


Potassium ferrocyanide. 




Chloride. 


Silver nitrate. 




Insoluble residue. 


Not completely soluble in 
water. 




Sodium. 


Flame test. 




Metallic. 


Hydrogen sulphide. 




Hyposulphite. 


Dilute acids. 




Nitrate. 


Ferrous sulphate, etc. 


Potassii Carbonas, - 


Sulphate. 


Barium chloride. 




Chloride. 


Silver nitrate. 




Sulphide. 


Add dilute acid. 




Cyanide. 


Ferrous sulphate, ferric 
chloride, and HC1 (blue 
color). 

Quantitative analysis. 




General. 




Sodium. 


Flame test. 




Sulphate. 


Barium cbloride. 




Calcium. 


Ammonium oxalate. 


Potassii Chloras, 


Chloride. 


Silver nitrate. 




Metals. 


Hydrogen sulphide. 




Nitrate and nitrite. 


Zinc and potassium hy- 






drate. 




Carbonate. 


Effervescence with acids. 


Potassii Citras, 


Sulphate. 


Barium chloride. 


Chloride, 


Silver nitrate. 




i Tartrate. 


A ppt. with acetic acid. 
Effervescence with acids. 


, 


Carbonate. 


Potassii Cyanidum, « 


iFerrocyanide. 


Ferric chloride. 


Sulphocyanate. 


Ferric chloride. 




General. 


Quantitative analysis. 


" 


Calcium. 


Ammonium oxalate. 


Potassii et Sodii _ 


Arsenum, lead, etc. 


Hydrogen sulphide. 


Ammonium salts. 


Potassium hydrate. 


Tartras, 


Sulphate. 


Barium chloride. 


. . 


Chloride. 


Silver nitrate. 



Page. 

268 
310 
630 
314 
291 
355 
168 
222 
310 
268 
165 
314 

87 
258 
162 
268 
268 
310 

117 

258 
90 
296 
473 
258 
222 
642 
117 
103 
310 
162 



90 
258 
347 
289 
310 
268 
304 



631 
90 
310 
117 

268 
258 



314 
310 
268 

314 
162 

162 
641 
117 

258 
98 
310 
268 



31* 



718 



APPENDIX. 



Table of Tests — Continued. 



Name of Preparation. 


Impurities. 


Tests. 


Page. 


Potassli et Sodii f 
Tartras, \ 


General. 


Quantitative analysis. 


632 


f 


Carbonate. 


Effervescence with acids. 


314 


Potassii Ferrocyani- 1 
dum, j 


Sulphate. 


Barium chloride. 


310 


Chloride. 


Silver nitrate. 


268 


I 


Ferricyanide. 


Silver nitrate, red ppt. 




I 


Calcium. 


Ammonium oxalate. 


117 




Carbonates. 


Effervescence with acids. 


314 


Potassii Hypophos- 1 


Chloride. 


Silver nitrate. 


268 


phis, 


Sulphate. 


Barium chloride. 


310 


| 


Phosphate. 


Magnesia mixture. 


331 


1 


General. 


Quantitative analysis. 


655 


Iodate. 


Starch and sulphuric acid. 
Hydrogen sulphide. 


76 




Arsenum, lead, etc. 


258 




Sulphate. 


Barium chloride. 


310 




Nitrate and nitrite. 


Zinc and potassium hy- 




Potassii Iodidum, 




drate (ammonia). 






Iron. 


Potassium ferrocyanide. 


162 




General. 


Quantitative analysis. 


643 




Cyanide. 


Ferrous sulphate and KOH 
(blue color). 






Iron. 


Potassium ferrocyanide. 


162 




Sulphate. 


Barium chloride. 


310 




Chloride. 


Silver nitrate. 


268 


Potassii Nitras, 


Calcium. 


Ammonium oxalate. 


117 


Metallic. 


Hydrogen sulphide. 


258 




Iodine. 


Starch. 


473 




Chlorate. 


Concentrated sulphuric 
acid (yellow). 






Sulphate. 


Barium chloride. 


310 


Potassii Perman- , 


Nitrate and chlorate. 


Sulphuric acid and di- 
phenylamine (color). 




ganas, 


General. 


Quantitative analysis. 


635 




Chloride. 


Silver nitrate. 


268 




Sodium. 


Flame test. 


90 




Arsenum, lead, etc. 


Hydrogen sulphide. 


258 




Iron, etc. 


Ammonium sulphide. 


165 


Potassii Sulphas, 


Magnesium. 


Sodium phosphate. 


122 




Chloride. 


Silver nitrate. 


268 




Calcium. 


Ammonium oxalate. 


117 


Pyrogallol, 


Fixed matter. 


Incineration. 


102 


f 

1 


Organic matter. 


Concentrated sulphuric 
acid (color). 




Quinidinx Sulphas, -j 


Morphine. 


Nitric acid. 


519 


Other cinchona alka- 


Solubility in ether. 




I 


loids. 








Organic. 


Sulphuric acid (color). 




1 


Cinchonine, einchoni- 


Sulphate of ammonium 




Quinina, \ 


dine, or quinidine. 


and ammonia (insolu- 
ble). 
Incineration. 




1 
I 


Fixed matter. 


102 


Quininx Bisulphas, ■* 


Organic. 


Sulphuric acid (color). 




General. 


Quantitative analysis. 


695 


( 


Fixed matter. 


Incineration. 


102 




Fixed matter. 


Incineration. 


102 


Quininx Hydrobro- 


Free water. 


Dry on water-bath and 




mas and Quininx ■ 




weigh. 


112 


Sulphas, 


Organic. 


Sulphuric acid (color). 




L 


General. 


Quantitative analysis. 


695 


' 


Sulphate. 


Barium chloride. 


310 




Fixed salts. 


Incineration. 


102 


Quininx Hydrochlo- 


Barium. 


Dilute sulphuric acid. 


103 


ras, 


Organic. 


Sulphuric acid (color). 






jFree water. 


Dry on water-bath. 


112 




General. 


Quantitative analysis. 


617 


Quininx Valerianas, 1 Fixed salts. 


Incineration. 


102 



APPENDIX. 



719 



Table of Tests — Continued. 



Name of Preparation. 



Quininse Valerianas, 
Resina Jalapse, 
Resorcinum, 

Saccharum, 

Saccharum Lactis, 
Salicinum, 

Salol, 
Santoninum, 



Sapo, 



Scammonium, 
Sinapis Alba' and 
Sinapis Nigra, 



Impurities. 



Soda, 



Sodii Acetas, 

Sodii Arsenas, 
Sodii Benzoas, 

Sodii Bicarbonas, 



Sulphate. 
Organic. 
Water. 

Soluble matter. 
Common resin. 

Fixed salt. 

Empyreumatic bodies. 
Grape-sugar. 

Insoluble matter. 

Cane-sugar. 
Mineral matter. 
Alkaloids. 

Sulphate. 

Chloride. 

Mineral matter. 

Carbolic or salicylic acid 

Mineral matter. 

Organic. 

Alkaloids. 

Water in excess. 

Animal fats. 



Metallic. 

Sodium carbonate, etc. 

Silica, etc. 
Alkalinity. 
Starch. 

Starch. 

Organic matter. 
Potassium. 
Arsenum, etc. 
Iron, etc. 
Calcium. 
Chloride. 
Sulphate. 
Silicate. 

Carbonate. 

Nitrate. 

General. 

Sulphate. 

Calcium. 

Chloride. 

Arsenum, etc. 

Iron, etc. 

Potassium. 

Arsenite. 

Metallic. 

Chloride. 

Potassium. 

Metallic. 

General. 

Sulphocyanate. 

Potassium. 

Normal carbonate. 

Arsenum, etc. 

Iron, etc. 



Tests. 



Barium chloride. 

Sulphuric acid (color). 

Heat on water-bath. 

Partially soluble in water. 

Ammonia solution, gelat- 
inized on cooling. 

Incineration. 

Colored solution in water. 

Silver nitrate and ammo- 
nia. 

Deposit on standing from 
solution. 

Cold sulphuric acid (color). 

Incineration. 

Mercuric-potassium 
iodide. 

Barium chloride. 

'Silver nitrate. 

j Incineration. 

I Ferric chloride (color). 

Incineration. 

Sulphuric acid (colored) 

Mercuric -potassium 
iodide. 

Dry at 110° ; not more than 
36 per cent. loss. 

Alcoholic 4 per cent, solu 
tion ; gelatinize on cool 
ing. 

Ammonium sulphide. 

Quantitative analysis and 
solubility in alcohol. 

Solubility in water. 

Vol. est. of alkalinity. 

Iodine. 

Iodine. 

Not clear aqueous solution 
Sodium cobaltic nitrite. 
Hydrogen sulphide. 
Ammonium sulphide. 
Ammonium oxalate. 
Silver nitrate. 
Barium chloride. 
Alcohol to aqueous solu 

tion (ppt.). 
Effervescence with acids. 
Sulphuric acid and indigo 
Quantitative analysis. 
Barium chloride. 
Ammonium oxalate. 
Silver nitrate. 
Hydrogen sulphide. 
Ammonium sulphide. 
Sodium cobaltic nitrite. 
Reduce AgN0 3 on boiling. 
Ammonium sulphide. 
Silver nitrate. 
Sodium cobaltic nitrite. 
Ammonium sulphide. 
Quantitative analysis. 
Ferric chloride. 
Sodium cobaltic nitrite. 
Phenolphtalein. 
Hydrogen sulphide. 
lAmmonium sulphide. 



Page. 

310 

112 



102 
467 

102 

571 

310 
268 
102 

102 

571 
102 

163 

663 

635 
473 

473 



258 
165 
117 
268 
310 



314 

291 
631 
310 
117 
268 
258 
165 



258 

268 

80 

258 

630 

162 

80 

87 

258 

165 



720 



APPENDIX. 



Table of Tests — Continued. 



Name of Preparation. 


Impurities. 


Teste. 


Page. 




Calcium. 


Ammonium oxalate. 


117 




Chloride. 


Silver nitrate. 


268 


Sodii Bicarbonas, 


Sulphate, etc. 


Barium chloride. 


810 




Ammonium. 


Heat with potassium hy- 








drate. 


98 




General. 


Quantitative analysis. 


631 




Chloride. 


Silver nitrate. 


268 




Hyposulphite. 


Not clear solution in dilute 




Sodii Blsulphi8, \ 




HC1. 




1 


Sulphate. 


Barium chloride. 


310 


I 


Arsenum, etc. 


Hydrogen sulphide. 


258 




Carbonate. 


Effervescence with acids. 


:5i4 




Arsenum, etc. 


Hydrogen sulphide. 


258 




Calcium. 


Ammonium oxalate. 


117 


Sodii Boras, 


Phosphate. 


Magnesia mixture. 


331 




Chloride. 


Silver nitrate. 


268 




Sulphate. 


Barium chloride. 


310 




Nitrate. 


Sulphuric acid and indigo. 


314 




Potassium. 


Sodium cobaltic nitrite. 


80 




Calcium. 


Ammonium oxalate. 


117 




Sulphate. 


Barium chloride. 


310 




Iodine. 


Chlorine- water and starch. 


473 


Sodii Bromidum, 


Bromate. 


Dilute sulphuric acid on 
salt (yellow). 






Arsenum, etc. 


Hydrogen sulphide. 


258 




Excess of moisture. 


Heat on water-bath and 








weigh. 


112 




Iron, etc. 


Ammonium sulphide. 


165 




Calcium. 


Ammonium oxalate. 


117 




Sulphocyanate. 


Ferric chloride. 


162 




Metallic. 


Ammonium sulphide. 


258 


Sodii Carbonas, 


Sulphate, etc. 


Barium chloride;. 


:no 




Potassium. 


Sodium cobaltic nitrite. 


80 




Chlorides. 


Silver nitrate. 


268 


I 


General. 


Quantitative analysis. 


631 




Tartrate. 


Alkalinity of ash. 


96 




Potassium. 


Sodium cobaltic nitrite. 


80 




Arsenum, etc. 


Hydrogen sulphide. 


258 


Sodii Ctdoras, 


Iron, etc. 


Ammonium sulphide. 


l(i, r ) 




Magnesium. 


Sodium phosphate. 


122 




Calcium. 


Ammonium oxalate. 


117 




Sulphate. 


Barium chloride. 


310 




Chloride. 


Silver nitrate. 


268 




Potassium. 


Sodium cobaltic nitrite. 


80 




Calcium. 


Ammonium oxalate. 


117 




Sulphate. 


Barium chloride. 


310 


Sodii Chloridum, 


Metallic. 


Hydrogen sulphide and 








ammonia. 


258 




Magnesium. 


Sodium phosphate. 


122 




Iodide or bromide. 


Starch and chlorine-water. 


473 


, 


Carbonate, etc. 


Effervescence with acids. 


314 




Potassium. 


Sodium cobaltic nitrite. 


80 




Calcium. 


Ammonium oxalate. 


J17 




Arsenum, etc. 


Hydrogen sulphide. 


258 


Sodii Ilypophosphis, ■ 


Chloride. 


Silver nitrate. 


268 




Phosphate. 


Magnesia mixture. 


331 




Sulphate. 


Barium chloride. 


310 




Iron. 


Potassium ferrocyanide. 


161 




General. 


Quantitative analysis. 


654 




Calcium. 


Ammonium oxalate. 


117 




Metallic. 


Hydrogen sulphide and 








ammonia. 


258 


Sodii Hyposulphis, - 


Carbonates, etc. 


Effervescence with acids. 


314 




Sulphide. 


Silver nitrate. 


307 


1 


Sulphate. 


Barium chloride. 


310 


1 


General. 


Quantitative analysis. 


647 



APPENDIX. 



721 



Table of Tests — Continued. 



Name of Preparation. 


Impurities. 


Tests. 


Page. 




Excess of water. 


Water-bath and weigh. 


112 




Potassium. 


Sodium bitartrate. 


79 




Calcium. 


Ammonium oxalate. 


117 




Arsenum, etc. 


Hydrogen sulphide. 


258 




Zinc, etc. 


Ammonium sulphide. 


165 




Iron. 


Potassium ferrocyanide. 


162 


Sodii Iodidum, 


Iodine, 
lodate. 


Starch. 

Acid aud starch. 


473 
296 




Sulphate. 


Barium chloride. 


310 




Cyanide. 


Ferrous sulphate and KHO 
(blue). 

Iron, zinc, and NaHO (am- 
monia). 

Quantitative analysis. 






Nitrate, etc. 






General. 


643 




Metallic. 


Ammonium sulphide. 


258 




Magnesium, etc. 


Ammonia and sodium 








phosphate. 


126 


Sodii Nitras, 


Potassium. 


Sodium bitartrate. 


79 


Iodide, iodate. 


Starch, H 2 S, and chlorine- 








water (blue). 






Sulphate. 


Barium chloride. 


310 




(Chloride. 


Silver nitrate. 


268 




Insoluble matter. 


Not soluble in water. 




Sodii Nitris, ■* 


Iodide. 


Starch and chlorine-water. 


473 




J Lead, etc. 


Hydrogen sulphide. 

Not completely soluble in 


258 




Calcium. 






• 


water. 






! Metallic. 


Hydrogen sulphide. 


258 


Sodii Phosphas and 
Sodii Pyrophos- - 
phas, 


Potassium. 
Carbonate. 


Sodium bitartrate. 
Effervescence with acids. 


79 
314 


Arsenum. 


Bettendorffs test. 


175 


Chloride. 


Silver nitrate and HN0 3 . 


268 




Sulphate. 


Barium chloride. 


310 




Hypophosphite, etc. 


Silver nitrate ppt., boiled 

(brown). 
Effervescence with acids. 




1 


Carbonate. 


314 




Metallic. 


Hydrogen sulphide'. 


258 


Sodii Salicylas, { 


Sulphate. 


Barium chloride. 


310 


1 


Chloride. 


Silver nitrate. 


268 


( 


Organic. 


Sulphuric acid chars. 


492 


f 


! Magnesium. 


Ammonium oxalate. 


117 


1 


; Carbonate. 


Effervescence with acids. 


314 


Sodii Sulphas, ^ 


Metallic. 


Hydrogen sulphide. 


258 


1 


Chloride. 


Silver nitrate. 


268 


I 


General. 


Quantitative analysis. 


682 


f 


! Sulphate. 


Barium chloride. 


310 


Sodii Snip?) is, \ 


1 Chloride. 


Silver nitrate. 


268 


1 Metallic. 


Hydrogen sulphide. 


258 


Hyposulphis. 


Acids liberate sulphur. 


347 


Sodii Sulphocar- J 
bolas, 


Sulphate. 
Chloride. 


Barium chloride. 
Silver nitrate. 


310 
268 


Metallic. 


Ammonium sulphide. 


257 




Fixed salts-. 


Incineration. 


102 


Sparteine Sidphas, < 


, Ammonium salts. 


Heat with potassium hy- 
drate. 
Specific gravity. 


98 
615 




General. 


Spiritus JEtJieris Ni- „ 


[Aldehyde. 


Potas. hydrate (brown). 




£>w, 


Deficiency of nitrous 
compound. 


Quantitative analysis. 


404 




Fusel oil. 


Disagreeable odor after 
evaporation. 




Spiritus Frumenti 


Glycerin. 


Sweet taste after evapora- 




and Spiritus Vini < 
Gallici, 




tion. 




Tannin. 


Ferric chloride. 


358 




Free acid. 


Potassium hydrate V. S., 








about 1.1 cc. 


636 



722 



APPENDIX. 



Table of Tests — Continued. 



Name of Preparation. 


Impurities. 


Tests. 


Page. 


f 


Arsenum, etc. 


Hydrogen sulphide. 


258 


1 


Iron, etc. 


Ammonium sulphide. 


62 


Strontii Bromidum, -! 


Iodine. 


Starch. 


473 


1 


General. 


Quantitative analysis. 


643 


I 


Barium. 


Dilute sulphuric acid. 


102 


Strontii lodidum, \ 


Arsenum, etc. 


Hydrogen sulphide. 


258 


Iron, etc. 
Barium. 


Ammonium sulphide. 
Dilute sulphuric acid. 


62 
102 


General. 


Quantitative analysis. 


643 


Metallic. 


Hydrogen sulphide and 








ammonia. 


258 




Carbonate, etc. 


Effervescence with acids. 


314 




Barium. 


Dilute sulphuric acid. 


102 


Strontii Lactas, ■{ 


Chloride. 
Butyrate, etc. 


Silver nitrate. 

Penetrating odor on heat- 
ing gently the acid solu- 
tion. 


268] 




Organic. 


Sulphuric acid (color). 




. 


General. 


Quantitative analysis. 


633 


Strychnina and i 
Strychninse Sul- * 
phas, 


Brucine. 


Nitric acid. 


529 


Mineral matter. 


Incineration. 1 102 


t 


Metallic, etc. 


Completely soluble in 1 






NaHO. 




Sulphur Lotum and 


Arsenum. 


Hydrogen sulphide. 


257 


Sulphur Prsecipi- • 


Acid. 


Litmus. 


96 


latum, 


Ammonia. 


Litmus. 


96 


I 


Selenium, 


Hydrochloric acid and 
KCN, boil (red). 




Sulphur Sublima- f 


Mineral matter. 


Incineration : not more 




twin, \ 




than .5 per cent. 


102 


Syr up us Acidi Hy- j 
driodici, ( 


Iodine. 


Starch. 


473 


Tamarindus, 


Traces of copper. 


Iron. 


161 


I 


Acids. 


Litmus. 


96 


Tcrebenum, % \ 


Unaltered oil of turpen- 
tine. 


Action on polarized light. 




I 


Resinous matter. 


Not completely volatile. 


71 


Terpen i Hydras, \ 


Free acid. 
Fixed salts. 


Litmus. 
Incineration. 


96 

102 




Thymin. 


Solution in caustic potash 

(oily drops). 
Non-volatile on water- 




Thymol, 


Paraffin, etc. 








bath. 


122 


, 


Metallic. 


Hydrogen sulphide and 








ammonia. 


258 


Tinctura Ferri Chlo- . 
ridi, 


Fixed alkalies. 


No residue after precip- 
itating the iron. 




Nitrate. 


Ferrous sulphate, etc. 


289 


1 


Oxychloride. 


Opalescent on diluting and 
boiling. 




(^ 






Veratrina, 


Mineral matter. 


Incineration. 


102 


f 


Free acid. 


Volumetric potassium hy- 




1 inum Album, ■{ 




drate. 


636 


I 


Tannic acid. 


Ferric chloride. 


358 


f 
| 


Aniline colors. 


Heated with chloroform 
and NaHO (isonitrile). 




Vinum Rubrum, -j 


Fuchsin. 
Free acid. 


Coloring silk. 
Volumetric potassium hy- 






drate. 


636 


I 


Tannic acid. 


Ferric chloride. 


358 


f 


Arsenum, etc. 


Hydrogen sulphide. 


258 


1 


Aluminium, etc. 


Filtrate from zinc hydrate ; 




Zinci Acetas, ■{ 




contain solid matter. 




. 


Sulphate. 


Barium chloride. 


310 


1 


Chloride. 


Silver nitrate. 


268 



APPENDIX. 



723 



Table of Tests — Continued. 



Name of Preparation. 


Impurities. 


Tests. 


Page. 


f 


Iodine. 


Starch and chlorine-water. 


473 




Arsenum, etc. 


Hydrogen sulphide. 


258 


Zinci Bromidum, ■{ 


Iron, calcium, etc. 


Insoluble in excess of am- 
monium carbonate. 




! 


Magnesium. 


Sodium phosphate. 


122 


i 


; General. 


Quantitative analysis. 


643 


f 


Arsenum, etc. 


Hydrogen sulphide. 


258 


i 


Iron, calcium, etc. 


Insoluble in excess of am- 




Zinci Carbonas Prx- J 
cipitatus, 




monium carbonate. 




Lead. 


Insoluble in dilute sul- 








phuric acid. 


251 




Alkali. 


Volumetric oxalic acid. 


634 




Oxychloride. 


Opalescent when diluted 
with alcohol. 






Arsenum, etc. 


Hydrogen sulphide. 


258 


Zinci Chloridum, 


Iron, calcium, etc. 


Insoluble in excess of am- 
monium carbonate. 






Sulphate. 


Barium chloride. 


310 




General. 


Quantitative analysis. 


643 




Arsenum, etc. 


Hydrogen sulphide. 


258 




Iron, calcium, etc. 


Insoluble in excess of am- 




Zinci Iodidum, 


Sulphate. 


monium carbonate. 
Barium chloride. 


310 




Magnesium. 


Sodium phosphate. 


122 




General. 


Quantitative analysis. 


643 




Arsenum, etc. 


Hydrogen sulphide. 


258 




Iron, calcium, etc. 


Insoluble in excess of am- 
monium carbonate. 






Chloride. 


Silver nitrate. 


268 


Zinci Oxidum, 


Magnesium. 


Sodium phosphate. 


122 




Carbonate. 


Effervescence with acids. 


314 




Sulphate. 


Barium chloride. 


310 




Lead, silicate, etc. 


Insoluble in sulphuric 








acid. 


257 




Insoluble matter. 


Insoluble in dilute hydro- 
chloric acid. 




Zinci Phosphidum, - 


Iron, etc. 


Potassium ferrocyanide. 
Ammonium sulphide. 


162 




Lead, etc. 


258 




Arsenum, etc. 


Hydrogen sulphide. 


258 




Insoluble matter. 


Insoluble in water. 






Arsenum, etc. 


Hydrogen sulphide. 


258 




Iron, calcium, etc. 


Insoluble in excess of am- 




Zinci Sulphas, 




monium carbonate. 






Magnesium. 


Sodium phosphate. 


122 




Chloride. 


Silver nitrate. 


268 




Free acid. 


Litmus. 


96 




Metallic. 


Ammonium sulphide. 


258 




i Magnesium. 


Sodium phosphate. 


122 


Zinci Valerianas, 


Acetate. 


Ferric chloride. 


300 




SButyrate. 


Turbid solution with cop- 








per acetate. 


364 




Sulphur. 


Dissolve in acids; H 2 S 




Zincum, 


Arsenum, etc. 


given off. 
Hydrogen sulphide. 


304 
258 




Iron, etc. 


Ammonium sulphide. 


165 



724 



APPENDIX. 



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APPENDIX. 
THE ELEMENTS. 



725 





Symbol 

and 
atomic 
value. 


Atomic 

weight. 

£. P. 


Atomic 
weight, 
U. S. P. 


Aluminium (AL VI ) 


A1 1V 

Sb v 

As v 

Ba TI 

Be 11 

Bi v 
B m 

Br 1 

Cd 11 

Cs 1 

Ca 11 
rjiv 

Ce VI 

CI 1 

Cr VI 

Co vl 

Cu 11 

D 11 

Eb m 

F 1 

Ga 

An™ 

H 1 

In VI 

I 1 
Ir iv 

Fe VI 
La 111 
Pb IV 
L 1 

Mg 11 
Mn VI 
Hg n 

Mo VI 

Ni VI 

Nb v 

N v 


27 
120 

75 

136.8 
9.1 
208 

11 

80 
112 
133 

40 

12 
141.5 

35.5 

52.5 

58.6 

63.3 
145 
166 

19 

70 

197 
1 
113.7 
127 
193 

56 
138 
206.4 
7 

24 

55 
200 

96 

58.6 

94 

14 


27.04 

119 6 


Antimony (Sb m ) 


Arsenum (As m ) ( 74 - 9 - Kessler ) 

Barium ( 136-84, Mari s nac • 137 - 12 > if ° = 16N t 
Beryllium (or Glucinum) ( 9 - 3 - Aw |S) . 
Bismuth (Bi m ) ( 210 > Dumas; 207 - 5 - if ° = 15 - 96 ) . 

Boron f 10 - 9 - Bei " zelius ; 10.97, Clarke\ 


74.9 
136.9 
9.03 

208.9 
10 9 


Bromine ( 79 - 75 - stas ; 79 - 96 - * ° - 16 ) 

Cadmium ( llL7 > Lenssen ) 


79.76 
111 5 


CsPsilllll f 132 - 7, Jonnson & Allen, Bunseu ; 133, if = 16\ 
Calcium ( 39 ' 9 ' Erdmaou and Marchand ; 40 if = 16\ 

Carbon (C 11 ) .' 


132.7 
39.91 
11 97 


Cerium (Ce m ) (^, Mended ) 


139 9 


Chlorine ( 35368 ' Stas ) 35.4, if 0= 16. . . 

Chromium (Cr 2 VI ) ( 5208 > Siewert ) 

Cobalt (Co 11 ) 


35.37 
52 ' 

58 6 


Conner f 63 - 12 ' Milloa & Commaille ; 63.3, if = 16\ 

Didymium (?) 


63.18 
142 


Erbium (?) , . 


166 


Fluorine ( 18 - 96 - Luca - Louyet ) 


19 


Gallium . 


69.9 


Germanium ( 72 - 3 > B°^ audraQ ) 

Glucinum, see Beryllium 

PrJrl ^A^^I^ /196.2, Berzelius ; 196.64, Kruss : 196. 85,\ 
UrOlU {2\.\1 ) ^ Thorpe and Laurie ) 

Hydrogen f 1 - 0025 ' if ° = 16 ) 


72.3 
9.03 

196.7 
1 


Indium 


113.6 


Iodine f 126 - 533 ' Stas ; 12 6.86, if o =ie\ 

Iridium 


126.53 
192.5 


Iron (Fe 11 and Fe 2 VI ) ( 55 - 9 - Dumas ) 

Lanthanium ( 138 - 85 - Clarke> Me y er ' and seunert^ > _ 
Lead (Pb 11 ) ( 206 - 9 ' stas ) 


55.88 
138.2 
206.4 


Lithium 


7.01 


Magnesium ( 24 -*- Van de Plaats - 0st ™ Id ) 

Manganese (Mn 11 and Mn IV ) (^YS) 

IVTnvmiT-ir ^199.8, Erdmann and Marchand: 200.1 to\ 

iueituiy ^ 200i4j otheTS J 

Molybdenum ( 95 ' 9 - Dumas; Debray ) . . . 
Nickel (NP) 


24.3 

54.8 

199.98 

95.9 

58.6 


Niobium (Columbium) 


93.7 


Nitrogen (N 1 and N m ) ("-o^stas; ,4.04, iy 


14.01 



726 



APPENDIX. 



The Elements {continued). 



Osmium ( 20 °- 0stwald ) 

Oxygen ( 15 - 96 > stas > Nilson ) 
Palladium 

Phosphorus (P 111 ) ( 30 - 96 > s <* r °" er ) 
Platinum («*.».« o = ie) 

Potassium ( 39 - 04 - stas ; 3SU < if ° = 16 ) , 

Rhodium ( 1041 : *™*™) 

Rubidium ( 85 - 2 > Bunsen ) 

Ruthenium ( m5 ' Berzelius ) 

Samarium 

Scandium . 



Selenium (or Selenion) ( 79 - vaiious <> bservers ) 
Silicon ( 28 - 3 - Clarke ) 



1 



5 ) 



Silver ( W1M - stas; 107 - 93 > if ° = 
Sodium T 22 ' 98 ' stas ; 23-05 ' if ° : 
Strontium ( 87 - 3 > if H = x ) .. 
Sulphur (S 11 and S IV ) . . 
Tantalum ( 182 - s > Van der piaats > ostwaid\ 
Tellurium f 128 ' Me y er > and seubert\ 
Terbium , 



Thallium ( 203 - 5 - Crookes ) 

Thorinum (or Thorium) (««*, ciarke) _ > 

Tin fSn 11 ) f 117 --*> Dumas ; 117.97, Clarke\ 

Titanium ( 50 ' Clarke ) 

Tungsten ( 183 - 6 - if H = x ) 

Uranium ( m8 > Ebelmen ) 

Vanadium ( 51 - 37 > Clarke ) 

Ytterbium , 

Yttrium ( 89 > 0stwald ) 

ZinC r 64 - 7, Axel Erdruann; 65.4, Ostwald\ 
ZirCOnium f 89 - 57 ' Clarke; 90.7, Ostwald^ 



Symbol 

arid 
atomic 
value. 


Atomic 

weight, 

B. P. 


Os lv 


185 


O n 


16 


Pd IV 


106.2 


pv 


31 


Pt lv 


194.4 


K 1 


39 


Rh IV 


104.3 


Rb 1 


85.4 


Ru lv 


104.2 


Sm 


149.6 


Sc 


44 


Se IV 


78.9 


Si IV 


28 


Ag 1 


108 


Na 1 


23 


Sr" 


87.5 


S VI 


32 


Ta v 


182 


Te VI 


125 


Tb 


159 


Tl m 


204 


Th n 


233 


Sn IV 


118 


Ti iv 


48 


W VI 


184 


XJVI 


240 


v v 


51 


Yb 


173 


yin 


90 


Zn 11 


64.9 


Zr IV 


90.4 



Atomic 
weight, 
U. 8. P. 



193 
15.96 

106.35 
30.96 

194.3 
39.03 

102.9 
85.2 

101.4 

149.62 
43.97 
78.87 
28.3 

107.66 
23 
87.3 
31.98 

182 

125 

159.1 

203.7 

231.9 

118.8 
48 

183.6 

238.8 
51.1 

172.6 
88.9 
65.1 
90.4 



The quantivalence or atomic value (for combination or exchange) of some elements is, apparently, 
variable : in the above table the full coefficients are given in the column of symbols, other common 
values in brackets. 

Atomic weights were somewhat obscurely termed equivalents by Wollaston. 

Other elements than the above exist. They are very rare. Some of tbe rarer so-called elements 
may not be truly elementary. 

Note. — Students must expect the figures representing the atomic weights of elements to vary 
slightly from time to time, in accordance with the advancement of knowledge in the direction of purity 
of materials and improvements in manipulation, and as regards modes of research and realization of 
chemical and physical analogies amongst elements. Atomic weights have also been founded, at 
different times, on different units or starting-points — namely, H = l and O = 16 ; H = 1 and 
O = 15.96; and O = 16 and H = 1.0025. In the foregoing table the atomic weights in large figures 
are those which, as a rule, at present will be found more usrful by English and American medical 
and pharmaceutical workers. (See a suggestive paper, with lists, by Venables, in the Chemical News, 
vol. lix. pp. 77 and 89, from the Journal of the Mlisha Mitchell Scientific Society, vol. v. part 2.) 



INDEX 



Abies balsamea, 412, 427 

excelsa, 425. 
Abri radix, 504. 
Abrin, 504. 

Abrus precatorius, 504. 
Absinthe, 500. 
Absinthin, 500. 
Absinthol, 417. 

Absolute alcohol, 442, 597, 615. 
Absorption spectra, 581. 
Acacia catechu, 359. 

suma, 359. 
Acacix gummi, 116. 

impurities in, 707. 
Acetal, 486. 
Acetamide, 431. 
Acetanilide, 431, 544 (table). 
Acetanilidum, 431. 

impurities in, 707. 
Acetate of ammonium, 93. 
solution of, 93. 

amyl, 406. 

copper, 192. 

ethyl, 300, 406. 

iron, 153, 300. 

lead, 211 

morphine, 517. 

potassium, 70. 

sodium, 83. 

zinc, 134. 
Acetates, 297. 

analytical reactions of, 300. 

decomposition of aqueous so- 
lutions of, 298. 
Acetic acid, 297, 298, 398. 
anhydrous, 299. 
constitution of, 387, 398. 
glacial, 299. 

volumetric estimation of 
free, 637. 

aldehyde, 484. 

anhydride, 299. 

ether, 300, 406. 

series of acids, 484. 

relations of, 490. 
Acetone, 300, 498. 
Acetonitrate of barium, 127. 

iron, 158. 



Acetonitrile, 483. 
Acetophenone, 498. 
Acetoximes, 515. 
Acetum, 398. 

cantharidis, 298. 

ipecacuanhse, 298, 537. 

opii, 298. 

scillse, 298. 
Acetyl, 298. 

chloride, 396. 
Acetylene, 411. 

series of hydrocarbons, 411. 
Acetylenes, relations to paraffins 

and defines, 410 
Acid carbonate of potassium, 71. 
of sodium, 83. 

salts, 73, 74, 302. 

solution of arsenic, 168 

tartrate of potassium, 62, 74, 
79, 319. 
Acidimetry, 639. 
Acids, of acetic series, 484. 

acrylic series, 491. 

analytical detection of, 369. 

antidotes to, 264. 

benzoic or aromatic series, 491. 

cinnamic series, 494. 

definition of, 263. 

dibasic, 493. 

free, estimated, 636. 

glyoxylic series, 490. 

hexabasic, 498. 

hydroxybenzoic series, 492. 

lactic series, 489. 

malic series, 496. 

of chlorine, 295. 

of phosphorus, 352. 

organic, 482. 

phthalic series, 496. 

polybasic, 498. 

quantitative estimation of, 637. 

succinic series, 495. 

sulphonic, 445. 

table showing the relations of 
acetic, lactic, and glyoxylic, 
490. 

acetic and dibasic 
series, 497. 

727 



728 



INDEX. 



Acids, table showing the relations 
of benzoic and hydroxyben- 
zoic, 493. 
tartaric series, 496. 
tetrabasic, 498. 
tribasic, 497. 

trihydroxybenzoic series, 494. 
Acidulous radicals, formulae and 
quantivalence of, 67, 124, 263. 
qualitative detection of, 

367. 
quantitative estimation of 

salts of, 677. 
tables to aid in the detec- 
tion of, 368, 369. 
volumetric estimation of, 
639. 
Acidum aceticum, 298. 

impurities in, 707. 
dilutum, 299. 
glaciale, 299. 

impurities in, 707. 
arsenosum, 168. 
benzoicum, 335. 
boricum, 333, 334. 

impurities in, 707. 
carbolicum, 453. 

liquef actum, 453. 
chromicum, 238. 

impurities in, 707. 
citricum, 323. 

impurities in, 707. 
gallicum, 360. 

impurities in, 707. 
hydrobromicum dilutum, 270. 

impurities in. 707. 
hydrochloricnm, 30, 265. 
impurities in, 708. 
dilutum, 265. 
hydrocyanicum dilutum. 281. 
impurities in, 708. 
hypophosphorum dilutum, 344. 

impurities in, 708. 
lacticum, 347. 
dilutum, 347. 

impurities in, 708. 
meconicum, '349. 
nitricum, 288. 

impurities in, 708. 
dilutum, 288. 
nitro-hydrochloricum, 288. 
dilutum, 187, 289. 
oleicum, 460. 

impurities in, 708. 
phosphoricum, 328. 
dilutum, 329. 

impurities in, 708. 
salicylicum, 492. 

impurities in, 708. 



Acidum sulphuricum, 310. 
aromaticum, 310. 
dilutum, 310. 

impurities in, 708. 

sulphurosum, 305. 

impurities in, 708. 

tannicum, 357. 

impurities in, 708. 

iartaricum, 319. 

impurities in, 709. 
Acipewser, 549. 
Acokanthera, 506. 
Aconine, 530. 
Aconiti ferocis radix, 530. 

folia, 529. 

heterophylli radix, 530. 

radix, 529. 
Aconitia, 529. 
Aconitic acid, 324. 
Aconitina, 529. 
Aconitine, 529. 
Aconitum ferox, 530. 

heterophyllum, 530. 

napellus, 530. 
Acorin, 420. 
Acorns calamus, 420. 
Acrinyl sulphocyanate, 451. 
Acrolein, 458. 
Acrylic acid, 489. 

aldehyde, 458. 
Actea racemosa, 509. 
Adeps, 462. 

benzoatus, 462. 

lanse, 460. 

impurities in, 709. 
hydrosus, 460. 

impurities in, 709. 
Adhesion, 57. 
Adipocere, 548. 
Adraganthin, 479. 
Advice to Students, xvii., 381. 
JZgle Marmelos, 359. 
Aerated bread, 470. 

water, 86. 
.Esculin, 537. 
Aether, 444, 448. 

impurities in, 709. 

aceticus, 406. 

impurities in, 709. 

purus, 448. 
Affinity, chemical, 38. 

units of, 56, 123. 
Agate, 354. 
Air, composition of, 27. . 

gas-burner, 23. 

influence of animals and plants 
on, 20. 

nitrogen in the, 25. 

oxygen in the, 16. 



INDEX. 



729 



Air, relative weights of the, 27. 

weight of 1 cubic cent., 620. 
of 100 cubic inches, 621. 
Ajowan oil, 415. 
Ajwain oil, 415. 

flowers, 415. 
Alwainka-puhl, 415. 
Alabaster, 106. 
Albumen, 544 

detection of, in urine, 573. 

vegetable, 548. 
Albumen ovi, 544. 
Albumenoids, 549, 647. 
Albumens, 549, 
Albumins, 549. 
Albumoses, 549. 
Alchemy, 13, 191 
Alcohol, absolute, 442, 597, 615. 

allylic, 451. 

anrylic, 363, 449. 

benzylic, 456. 

butylic, 364, 449. 

cetylic, 450. 

cerylic, 450. 

cinnamic, 495. 

decylene, 452. 

deodorized, 443. 

ethylic, 439. 

from sugar, 439. 

hydroxybenzylic, 456. 

impurities in, 709. 

melissic, 450. 

methylic, 437. 

pentylic, 449. 

phenic, 452. 

propargyl, 411. 

propenyl, 457. 

propyl ic, 447. 

purity of, 444. 

quantitative estimation of, 704. 

real, 442. 

salicylic, 456. 

test for, 444. 

tolyl, 455. 
Alcoholates of bromal, 488. 

of chloral, 488. 
Alcoholic drinks, 441. 
Alcoholometer, 616. 
Alcohols, 436. 

allylic series, 451. 

benzylic, 455. 

dihydric, 409. 

ethylic series, 456. 

hexhydric, 465. 

monhydric, 436. 

penthydric, 465. 

primary, 437. 

saligenin, 455. 

secondary, 437. 



Alcohols, tertiary, 437. 

tetrahydric. 465. 

trihydric, 457, 465. 
Aldehyde, 483. 

acrylic, 457. 

benzoic, 336, 432, 491. 

cinnamic, 417. 

cumic, 417. 

euodic, 419. 

formic, 484. 

glycolic, 409. 

lauric, 419. 

orthohydroxybenzoic, 494. 

oxalic, 409. 

parahydroxybenzoic, 494. 

rutic, 419. 

salicylic, 407, 457, 494. 

test for, 485. 
Aldehydes, 482. 

general reactions, 483. 

general formation, 482. 
Aldose, 467. 
Aldoximes, 515. 
Ale, 478. 

Alexandrian senna, 501. 
Alizarate of potassium, 434. 
Alizarin, 434, 554. 
Alkalies, analytical separation of 
the, 101. 

antidotes to, 264. 

quantitative estimation of the, 
628. 
Alkalimetry, 628. 

Alkaline carbonates, volumetric 
estimation of the, 631. 

earths, 127. 

solution of arsenic, 166. 
Alkaloids, 510. 

animal, 512. 

antidotes to the, 516. 

nomenclature of, 515. 

poisonous, examination for, 566, 
et seq. 

reagents for, 570. 

vegetal, 512. 

vegeto-animal, 515. 
Alkanet, 554. 
Alkanna tinctoria, 554. 
Alkyl salts, 407, 484. 
Allium, 452. 
Allotropes, 482. 
Allotropic bodies, 482. 
Allotropy, 480. 
Alloxan, 362. 
Alloy, 196. 
Allyl cyanide, 451. 

sulphide, 452. 

sulphocyanate, 451. 
Allylene, 411. 



730 



INDEX. 



Allylic series of alcohols, 451. 

alcohol, 451. 
Almond-oil, 463. 
Almonds, oil of bitter, 491, 499. 

test for nitroben- 
zol in, 500. 
Aloe barbadensis, 434. 

purificata, 434. 

socotrina, 434. 
Aloes, 434. 
Aloins, 434. 

formulae of, 435. 
Alstonia const ricta, 537. 

scholaris, 537. 
Alsfconicine, 537. 
Alstonine, 537. 
Althaea officinalis, 479. 
Alum, 138. 

cake, 139. 

chrome, 139, 338. 

dried, 140. 

flour, 139. 

impurities in, 709. 

iron, 139. 

potash, 139. 

roche or rock, 140. 

soda, 139. 
Alumen, 138. 

exsiccatum, 140. 

impurities in, 709. 
Alumina, 140. 
Aluminium, 139. 
• analytical reactions of, 140. 

and ammonium sulphate, 138. 

and sodium, double chloride of, 
138. 

bronze, 138. 

chloride of, 138. 

derivation of word, 33. 

detection of, in presence of iron 
and zinc, 163. 

hydrate, 140. 

oxide, 140. 

quantitative estimation of, 668. 

separation of, from chromium 
and iron, 240. 

silicate, 138. 

steel, 138. 

sulphate, 140. 
Amalgam, 194. 

ammonium, 91. 
Amber, 356. 

oil of, 356. 
American pennyroyal, 418. 

turpentine, 412. 
Amianth, 354. 
Amidacetic acid, 552. 
Amide-bases, 431, 510, 515. 
Amides, 206, 431. 



Amido-acet-phenetidin, 431. 
Amido-benzene, 430, 513. 

-chloride of mercury, 200. 
Amido-succinamic acid, 496. 
Amidogen, 206, 431 
Amines, constitution of, 431. 
Ammonia, 91, 92. 

acetate, 93. 

benzoate, 95, 337. 

carbonate, 93. 

citrate, 95. 

detected by Nessler's test, 630. 

fetid spirit of, 94. 

gas, composition of, 91, 130. 

in drinking-water, 630. 

nitrate, 94. 

oxalate, 95. 

phosphate, 95. 

preparation of, 92. 

solution of, 92. 

sulpbate, 91. 

type, 379. 

volcanic, 91. 

volumetric estimation of solu- 
tions of, 629. 
Ammoniacal liquor, 92. 

salts, sources of, 91. 
Ammoniacum, 427. 
Ammonise benzoas, 95, 337. 

carbonas, 93. 

liquor, 92. 

fortior, 92. 

nitras, 94. 

phosphas, 95. 

sesquicarbonas (see Ammonii Car- 
bonas). 

spiritus aromaticus, 94. 
foetidus, 94. 
Ammoniated mercury, 206. 

varieties of, 206. 
Ammonii acetatis, liquor, 93. 

benzoas, 95, 337. 

impurities in, 709. 

bromidum, 95, 271. 

impurities in, 709. 

carbonas, 9.3. 

impurities in, 34, 709. 

chloridum, 91. 

impurities in, 709. 

citratis, liquor, 95. 

nitras, 94. 

impurities in, 709. 

phosphas, 95. 

sulphas, 91. 
Ammonio-chloride of mercury, 206, 
207. 

-citrate of iron, 154. 

-magnesian phosphate, 122, 330. 

-nitrate of silver, 178, 207. 



INDEX. 



731 






Arnrnonio-sulphate of copper, 177. 
magnesium, 685. 

-tartrate of iron, 154. 
Ammonium, 90. 

acetate, 93. 

amalgam, 91. 

analytical reactions of, 98. 

and bismuth, citrate of, 254. 

and magnesium, arsenate, 122. 
phosphate, 122, 330. 

and platinum double chloride, 
99, 249. 

arsenate, 169. 

aspartate, 349. 

benzoate, 95, 337. 

bicarbonate, 94. 

bromide, 95, 271. 

vol. estimation of, 630. 

carbamate, 93. 

carbonate, 93. 

solution of, 94. 

chloride, 91. 

chromate, 238. 

citrate, 95. 

cyanate, 339. 

derivation of word, 32. 

derivatives, 207. 

hydrate, 92. 

iodides, 273, 274. 

molybdate, 331. 

nitrate, 94, 288. 

oxalate, 95. 

periodide, 273. 

phosphate, 95. 

potassium and sodium, separa- 
tion of, 101. 

quantitative estimation of, 663. 

salts, source of, 91. 
volatility of, 99. 

sulphate, 91. 

and ferrous sulphate, 652. 

sulphide, 96. 

sulphydrate, 96. 

tartrate, 99. 

urate, 362. 

volumetric estimation of car- 
bonate of, 630. 
Amomum melegueta, 418. 
Amorphous alkaloid, 526. 

meaning of, 78. . 

phosphorus, 328. 
Amphicreatinine, 513. 
Amrad, 479. 
Amygdala amara, 463, 499. 

dulcis, 463, 499. 
Amygdalin, 499. 
Amyl, acetate, 406. 

nitrite, 351, 407. 

valerianate, 363, 407. 



Amyl nitris, 351, 407. 

impurities in, 710. 
Amylamine, 511. 
Amylene, 408. 

hydrate, 450. 
Amylic alcohols, 363, 449. 
Amyloids, 472. 
Amyloses, 472. 
Amylum, 472. 

impurities in, 710. 
Amyric acid, 426. 
Amyrin, 426. 
Anacyclus pyrethriim, 425. 
Analogies between chlorine, bro- 
mine, and iodine, 272, 278. 
Analogy of carbon, boron, and sil- 
icon, 356. 
of oxygen, sulphur, selenium, 

and tellurium, 302. 
of sodium and potassium salts, 

89. 
of nitrogen, phosphorus, arse- 
num, and antimony 166, 332, 
512. 
Analysis, blowpipe, 372, 373. 
gas, 361, 560. 
gravimetric, 592, 659. 
meaning of word, 62. 
of gases and vapors, 560. 
of insoluble salts, 375, et seq. 
of medicines, 557. 
of salts, 376. 
of substances having unknown 

properties, 557. 
organic, 384. 
practical, 100, 257. 
proximate, 688. 
quantitative, 592. 
spectral, 262, 560. 
systematic, for the detection 
and separation of the metals, 
101, 125, 163, 186, 220, 257. 
ultimate, 688. 
volumetric, 625. 
Analytical chemists, 14. 

detection of the acidulous radi- 
cals of salts soluble in water, 
365. 
memoranda, 222, 259. 
Anamirta paniculata, 506. 
Anamirtin, 506. 
Anchusa tinctoria, 554. 
Anchusin, 554. 
Andira Araroba, 338. 
Andrographis paniculata, 509. 
Andropogon citratus, 420. 
nardus, 417. 
schcenanthus, 418. 
Aneroid barometer, 594. 



732 



INDEX. 



Anethene, 415. 

Anethol, 415. 

Angelate of potassium, 415. 

Angelic acid, 415. 

powder, 181. 
Angelica, 428. 
Angostura bark, false, 527. 

true, 536. 
Angosturin, 536. 
Anhydride, acetic, 299. 

antimonic, 181. 

antimonious, 181. 

arsenous, 168. 

boric, 338. 

carbonic, 312. 

cblorochromic, 240, 278. 

chromic, 239. 

molybdic, 332. 

nitric, 288, 290. 

nitrous, 289, 290. 

phosphoric, 26, 313, 349. 

phthalic, 591. 

silicic, 355. 

sulphocarbonic, 314. 

sulphuric, 310. 

sulphurous, 305. 
Anhydrides, 85, 300. 
Anhydrochromate of potassium, 

238. 
Anhydrous bodies, 85. 

arsenous acid, 168. 
Anhydrous chromic acid, 239. 

ferrous chloride, 149. 

nitric acid, 288. 

perchloride of iron, 148. 

stannic sulphide, 244. 

sulphate of copper, 192. 
Aniline, 431, 513. 

blue, 557. 

colors, 557. 

green, 557. 

red, 557. 

yellow, 557* 
Animal alkaloid, 512. 

charcoal, 112. 

decolorizing power of, 113. 

rouge, 337. 

starch, 472. 
Animals and plants, complementary 

action of air, 19. 
Aniseed oil, 415. 
Anise-fruit, 415. 
Anisum, 415. 
Annatto, 554. 
Anode, 245. 
Anthemen, 415. 
Anthemis, 415, 509. 
Anthemis nobilis, 415. 
Anthracene, 434, 554. 



Anthracite, 241. 
Anthraquinone, 434. 
Antichlor, 306. 
Antidotes to acids, 264. 

alkalies, 264. 

alkaloids, 516. 

antimony, 186. 

arsenic, 152, 168. 

barium, 104. 

carbolic acid, 454. 

copper, 194. 

cyanides, 283. 

hydrochloric acid, 268. 

hydrocyanic acid, 283. 

lead, 215. 

mercury, 209. 

nitric acid, 292. 

oxalic acid, 317. 

silver, 220. 

sulphuric acid, 311. 

tin, 244. 

zinc, 137. 
Antifebrin, 431. 
Antimonial wine, 182. 
Antimonic anhydride, 181. 

chloride, 180. 

oxide, 181. 
Antimonii chloridi, liquor, 180. 

oxidum, 181. 

impurities in, 710. 
Antimonious anhydride, 181. 

chloride, 181. 

oxide, 181. 

oxychloride, 181. 
Antimonii et potassii tartras, 182. 
impurities in, 710. 

sulphidum, 180. 

impurities in, 710. 

sulphuratum, 182. 

impurities in, 710. 
Antimonium tartaratum, 182, 319. 
impurities in, 710. 
quantitative estimation of 
antimony in, 671. 
Antimoniuretted hydrogen, 185. 
Antimony, 180, 

analytical reactions of, 184. 

and arsenic, analytical separa- 
tion of, 187. 

and potassium, tartrate of, 182, 
319. 

antidote to, 186. 

black, 180. 

bromide, 180. 

butter of, 180. 

chloride, 180. 

crocus, 180. 

crude, 180. 

derivation of word, 33. 



INDEX. 



733 






Antimony from arsenic, to distin- 
guish, 187. 

glass, 180. 

hydride, 184. 

in organic mixtures, detection, 
of, 562. 

iodide, 180. 

oxide, 181. 

oxychloride, 181, 184. 

oxysulphide, 182. 

pentachloride, 180. 

potassio-tartrate, 182. 

quantitative estimation of, 647, 
671. 

solution of chloride of, 180. 

sulphide, 177, 184. 

sulphur, salts of, 183. 

sulphurated, 182. 

tartarated, 182. 

volumetric estimation, 647. 
Antip3 r rine, 431.- 
Antiseptic, 454, 457, 492. 
Antozone, 585. 
Apatite, 332. 
Apocynum, 509. 
Apomorphinse hydrochloras, 520. 
Apomorphine, 519. 
Aporetine, 338. 
Apothecaries, 14. 
Apparatus, xii., xiii., 16. 

for experiments, xiii. 

for volumetric analysis, 626. 

lists of, xiii. 
Apple essence, 407. 

oil, 407. 

wine, 441. 
Aqua, 129. 

impurities in, 710. 

ammonise, 92. 
fortior, 92. 
impurities in, 710. 

amygdala amara, 499. 

anethi, 414. 

anisi, 414. 

aurantii florum fortior, 416. 

camphorse, 422. 

carui, 414. 

impurities in, 710. 

(Mori, 29, 267. 

chloroformi, 414. 

cinnamomi, 414. 

creasoti, 453. 

destillata, 129. 

impurities in, 710. 

foeniculi, 414. 

fortis, 288. 

duplex, 288. 
simplex, 288. 

hydrogenii oxidum, 103. 
H2 



Aqua hyd. oxidum, impurities in, 710. 

laurocerasi, 282, 500, 641. 

menthse piperitse, 414. 
viridis, 414. 

pimentse, 414. 

regia, 187, 288. 

rosse, 414, 419. 

sambuci, 414. 
Arabic acid, 478. 
Arabin, 116. 
Arabinose, 466. 
Arachidic acid, 490. 
Arachin, 464. 
Arachis, 464. 

hypogoea, 464. 

oil, 464. 
Araroba powder, 338. 
Arbor Dianse, 220. 
Arbutin, 359, 501. 
Archil, 555. 
Arctium lappa, 509. 
Arctostaphylos uva ursi, 501. 
Are, 604. 
Areca catechu, 360. 

nuts, 360. 
Arecaine, 360. 
Arecoline, 360. 
Arekane, 360. 
Areometers, 616. 

Argal. Vide Acid Tartrate of Po- 
tassium. 
Argent-ammon-ammonium, nitrate 

of, 207. 
Argenti et potassii nitras, 218. 

cyanidum, 220. 

iodidum, 220. 

nitras, 216. 

impurities in, 710. 

nitras dilutus, 218. 
fusus, 218. 

oxidum, 219. 

impurities in, 710. 
Argentic chloride, sulphide, etc. 

Vide Salts of Silver. 
Argentiferous galena, 216. 
Argentum, 33. 

purificatum,, 218. 
Argol. Vide Acid Tartrate of Po- 
tassium. 
Armenian bole, 555. 
Armoracise radix, 415. 
Arnatto, 554. 
Arnica flores, 423. 
Arnicse rhizoma, 423. 
Arnicin, 423. 
Arnotto, 554. 
Aromatic acids, 491. 

glycols, 456. 

series of hydrocarbons, 429. 



734 



INDEX. 



Arrow-poison, 506. 
Arrowroot starch (fig.), 475. 
Arsenate of ammonium, 169. 
barium, 105, 178. 
calcium, 178. 
copper, 178. 
iron, 146, 170, 178. 
magnesium and ammonium, 

122. 
silver, 178, 220. 
sodium, 170. 

volumetric estimation of, 
646. 
zinc, 178. 
Arsenates, 169. 
Arsenic, 33, 167, 168. 
acid, 169. 

solution of, 169. 
and arsenical solutions, vol- 
umetric estimation of offi- 
cial, 646. 
anhydride, 169. 
antidotes to, 152, 168. 
derivation of word, 33. 
in carbonate of potassium, so- 
lution of, 167. 
in hydrochloric acid, solution 

of, 168. 

odor of, 169. 

white, 167. 

Arsenical ores, 167. 

sulphur, 176. 
Arsenicum, 33, 168. 
Arsenide of cobalt, 234. 
Arseni iodidum, 167. 
Arsenio-sulphide of iron, 167. 

nickel, 236. 
Arsenous acid, 168. 
anhydride, 168. 
oxide, 168. 
sulphide, 176. 
Arsenite of copper, 178, 194. 
potassium, 168. 
silver, 177. 
sodium, 168. 
Arsenites, 168. 
Arsenum, 167, 168. 

analytical reactions of, 171. 
and antimony, analytical sep- 
aration of, 187. 
Bettendorff's test, 177. 
bromide, 166. 
chloride, 166. 

detection of, in metallic copper, 
173. 

in organic mixtures, 562. 
Fleitmann's test for, 175. 
from antimony, to distinguish, 
187. 



Arsenum, hydride, 174. 

iodide, 167. 

Marsh's test for, 173. 

molecular weight of, 166. 

quantitative estimation of, 670. 

red nati ve sulphide of, 167. 

reduction of arsenates to arse- 
nites, 169. 

Eeinsch's test for, 172. 

sources of, 167. 

sulphide, 167, 176. 

yellow native sulphide of, 167. 
Arseniuretted hydrogen, 174. 
Arsiues, 512. 
Art of Chemistry, 13. 
Artemisia absinthium, 499. 

pauciflora, 507. 
Artificial alkaloids, 510. 

gastric juice, 550. 
Arum-root, 360. 
Asafcetida, 427. 
Asagrxa officinalis, 543. 
Asbestos, 354. 
Asclepidin, 509. 
Asclepias taberosa, 509. 
Aselline, 463. 
Aseptol. 445. 
Ash, 102. 

black, 88. 

bone, 112. 

soda, 89. 
Asparagine, 349, 496. 
Aspartate of ammonium, 349. 
Aspidospermine, 530. 
Aspirator, water, 309. 
I Asphalte,' 427. 
Asymmetrical atoms, 320. 
Assafoetida, 427. 
-ate, meaning of, 73, 76. 
A tees, 530. 
Ateesine, 530. 
Atis, 530. 
Atmosphere, aqueous vapor in, 27. 

carbonic acid in, 313. 

composition of, 27. 

minor constituents, 27. 

nitrogen in, 25. 

oxygen in, 25. 
Atmospheric pressure, quantitative 

determination of, 593. 
Atom, definition of, 57. 

weights, definition of, 59. 
Atomic attraction, 139. 
Atomic weights as indicated by — 

chemical " periodicity," 380. 
properties, 387, 392. 

density of gases and vapors, 53, 
619. 

electricity, 623. 



INDEX. 



735 



Atomic weights as indicated by — 

isomorphism, 55. 

specific heat, 622. 

substitution, 193. 
Atomic proportions, 52, 198. 

theory, 51, 54, 198, 380. 

weights, 52. 
Atomicity, 56. 
Atoms, 36, et seq. 

conception of, 389. 

quanti valence of, 56. 
definition of, 59. 
Atropa belladonna, 531. 
Atropia, 530. 
Atropina, 532. 

impurities in, 710. 
Atropinse sulphas, 533. 
Atropine, 531. 
Attar of rose, 419. 
Attraction, atomic, 139. 

molecular, 139. 
Aurantii cortex, 415, 509. 

fructus, 415. 
Auri et sodii chloridum, 246. 
Auric chloride, 246. 

sulphide, 246. 
Aurous salts, 246. 
Aurum, 34. 

Australian kino, 359. 
Avense farina, 473. 
Avignon grains, 553. 
Avogadro's and Ampere's "law/ 1 

53. 
Azadiracta indica, 509. 
Azedarach, 509. 
Azo, 513. 
Azobenzene, 436. 
Azoimide, 515. 
Azoxybenzene, 430. 

Bacteria, 440. 
Bacterium aceti, 484. 

mycoderma, 297. 
Bael-fruit, 359. 

mucilage, 479. 
Bahia powder, 338. 
Baking-powder, 470. 
Balance, 600. 
Balloons, coal-gas for, 24. 

hydrogen for, 24. 
Balm-of-Gilead fir, 427. 
Balsam, Canada, 412, 427. 

copaiva, 426. 

Gurjun, 426. 

of Peru, 422, 495. 

of storax, 422, 495. 

of Tolu, 422, 495. 
Balsamodendron myrrha, 428. 
Balsams, 422. 



Balsamum pernvianum, 422, 495. 
impurities in, 710. 

tolutannm, 422, 495. 
Baptin, 532. 
Baptisia tinctoria, 532. 
Baptism, 532. 
Baptitoxine, 532. 
Barbadoes aloes, 435. 
Barbaloin, 435. 
Barberry, 533. 
Baric chloride, nitrate, etc. Vide 

Salts of Barium. 
Barii dioxidum, 103. 

vol. est. of, 663. 
Barium, 103. 

acetonitrate, 127. 

analytical reactions of, 104. 

and calcium, separation of, 
from magnesium, 126. 

antidotes to, 104. 

arsenate, 105. 

carbonate, 103. 
native, 103. 

chloride, 103. 

chromate, 105. 
neutral, 105. 

derivation of word, 32. 

detection of, in presence of cal- 
cium and magnesium, 117, 
126. 

dioxide, 103. 

vol. est. of, 663. 

flame, 105. 

hydrate, 103. 

nitrate, 103. 

oxalate, 105, 317. 

oxide, 103. 

peroxide, 103. 

phosphate, 105, 332. 

quantitative estimation of, 664. 

salts, antidote to, 104. 

sulphate, 103. 

sulphide, 103. 

sulphite. 307. « 

sulphocarbolate, 454. 
Barley starch (fig.), 475. 

sugar, 471. 
Barometer, 593. 
Barwood, 420, 555. 
Baryta, 103. 

nitrate, 103. 

water, 103. 
Barytes, nitrate of, 103. 
Basalt, 138. 
Base, meaning of, 262. 

organic, 392. 
Basic, meaning of, 262. 
Bassorin, 116, 479. 
Bastard saffron, 555. 



736 



INDEX. 



Basylous hydrocarbons, 392. 

radicals, 60, 124. 
Bath brick, 354. 
Bauxite, 138. 
Bay rum, 441. 

salt, 81. 
Bearberry, 359. 
Beaver tree, 509. 
Beberia, or Beberine, 532. 
Bebeeru, 532. 
Beberinse sulphas, 532. 
Bebirine, 532. 
Beer, 441, 478. 
Beeswax, 450. 
Beetroot, 469. 
Beheuic acid, 490. 
Belse fructus, 359. 
Belladonnse folia, 531. 

radix, 531. 
Bell-metal, 242. 
Bend glass tubes, to, 17. 
Benne oil, 464. 
Benzaldehyde, 492, 500. 

artificial, 500. 
Benzene, 429. 

disulphonic acid, 455. 

nitro, 430. 

series of hydrocarbons, 429. 
constitution of, 432. 

sulphonic acid, 445. 
Benzin, 398, 430. 
Benzine-Collas, 430. 
Benzinum, 398. 

impurities in, 710. 
Benzoate of ammonium, 95. 

of iron, 337. . 

of sodium, 337. 
Benzoated lard, 337. 
Benzoates, 335. 

analytical reactions of, 337. 
Benzodichloride, 337. 
Benzoene, 429, 431. 
Benzoic acid,. 335, 431, 491. 

aldehyde, 336, 431, 491. 
Benzoin, 336, 422. 
Benzoinum, 335, 422. 
Benzol, 429. 
Benzoline, 398. 
Benzotrichloride, 336. 
Benzoyl chloride, 492. 

ecgonine, 534. 

hydrate, 492, 534. 

hydride, 492. 

sulphonic imide, 445. 
Benzyl benzoate, 495. 

cinnamate, 495. 

derivatives, 431. 

hydrate, 492, 495. 
Benzylic alcohol, 456, 495. 



Benzylic alcohols, 452. 
Berbamine, 533. 
Berber ine or Berberia, 533. 
Berberis cortex, 533. 
Bergamot oil, 416. 
Berlin blue, 555. 

red, 555. 
Berthollet's laws, 379. 
Beryllium, 725. 
Betaine, 515. 
Beta-naphtol, 434. 
Betel-nuts, 360. 

Bettendorff's test for arsenum, 175. 
Betula lenta, 407. 
Bhang, 424. 
Bi-, the prefix, 73. 
Bibasic. See Dibasic. 
Bibirine, 532. 
Bibiru, 532. 

Biborate of sodium, 333. 
Bibulous paper, 109. 
Bicarbonate of ammonium, 94. 

potassium, 71. 

sodium, 83, 313. 

chemically pure, 628. 
lozenges, 87. 
Bicarbonates, test for, 315. 
Bichloride of mercury, 201. 
Bichromate of potassium, 238. 
Bikh, 530. 
Bile, 552. 

detection of, in urine, 575. 

test for presence of, 552. 
Biliary calculi, 589. 
Bimeconate of morphine, 517. 
Binary hypotheses, 286. 
Birch oil, 407. 
Bish, 533. 
Bismuth, 251. 

analytical reactions of, 254. 

and ammonium, solution of 
citrate of, 254. 

carbonate, 253. 

citrate, 253. 

derivation of word, 34. 

hydrate, 254. 

iodides, double, 253, 571. 

lozenge, 252. 

nitrate, 251. 

oxide, 253. 

quantitative estimation of, 772. 

salts, composition of, 252, 253. 

subcarbonate or oxycarbonate, 
253. 

subnitrate or oxynitrate, 252. 

sulphate, 254. 

sulphide, 254. 
Bismuthi citras, 253. 

impurities in, 711. 



INDEX. 



737 



BismutM et ammonii citras, 254. 
oxidum, 253. 
subcarbonas, 253. 

estimation of bismuth in 

772. 
impurities in, 711. 

subnitras, 252. 

impurities in, 711. 
Bismnthuni, 251. 

purificatum, 251. 
Bisulphide of carbon, 314. 
Bisulphite of lime, 306. 

of sodium, 306. 
Bitartrate of potash, 79. 
Bitter almonds, oil of, 491, 499. 

cassava, 472. 

orange-rind oil, 415. 

principles, 509. 
Bittern, 269. 
Bitter-sweet, 541; 
Bituminous coal, 241. 
Bivalence, 56. 

Bivalent radicals, 56, 67, 123. 
JBixa orellana, 554. 
Bixin, 554. 
Black alder-bark, 338. 

antimony, 179. 

ash, 88, 313. 

band, 142. 

bone-, 112. 

cherry-bark, 500. 

coloring-matters, 556. 

dyes, 556. 

flux, 169. 

haw, 510. 

hellebore, 505. 

ink. 162, 556. 

lead, 30. 

oxide of copper, 191. 
of iron, 142. 
of manganese, 231. 
of mercury, 505. 

pepper, 541. 

snake-root, 509. 
Bladder-green, 556. 
Blanc de perle, 253, 556. 
Bleaching by chlorine, 29. 

liquor, 115. 

powder, 114. 
Blende, 131. 

Blistering collodion, 480. 
Block tin, 241. 
Blood, 545. 

. composition of, 546. 

detection of, in organic matter, 
584. 

hydrocyanic acid in the, 284. 

root, 541. 

stains, 584. 

62* 



Blowpipe analysis, 372. 

flame, 135. 
Blue coloring-matters, 555. 

cohosh, 509. 

copperas, 144, 192. 

flag, 509. 

gum tree, 359. 

indigo, 291. 

ointment, 195. 

pill, 195. 

Prussian, 341. 

stone, 192. 

Turnbull's, 161, 342. 

vitriol, 144, 192. 
" Boiled oil," 463. 
Boiling-point, definition of, 597. 
Boiling-points of various sub- 
stances, 597. 
Boldine, 416. 
Boldo, 416. 
Bonduc-seeds, 509. 
Bone-ash, 112. 

-black, 112. 

-earth, 112, 327. 
Bone oil, 513. 

Bones, composition of, 112, 327. 
Boneset, 509. 
Boracic acid, 333. 
Borate of glyceryl, 335. 
Borates, 333. 

analytical reactions of, 334. 
Borax, 333. 

bead, 232. 
Bordeaux turpentine, 412. 
Boric acid, 333. 

as an antiseptic, 547. 

anhydride, 333. 
Borneene, 421. 
Borneo camphor, 451. 
Borneol, 451. 
Boron, 333. 

chloride, 333. 

derivation of word, 34. 

flame, 334. 

fluoride, 333. 

molecular weight of, 333. 
Borotartrate of potassium, 334. 
Bos taurus, 552. 
Boswellia, 428. 
Botany Bay kino, 359. 
Bourdon barometer, 594. 
Boyle's law, 53, 619. 
Brandy, 443. 
Brass, 131. 
Brassica alba, 451. 
juncea, 451. 

nigra, 451. 
Bray era, 506. 
Brazil powder, 338. 



738 



INDEX. 



Brazil wood, 556. 
Bread, 471. 

aerated, 471. 
Bread-crumb, 471. 
Bread-making, 471. 
Breidin, 426. 
Brezilin, 554. 
Bricks, 355. 
Bright's disease, 474. 
Britannia metal, 180, 210, 241. 
British gum, 477. 
Bromal, 488. 

alcoholates, 488. 

hydrate, 488. 
Bromate of potassium, 77. 
Bromates, 77, 271, 296. 
Bromic acid, 77, 296. 
Bromide of — 

ammonium, 95, 270. 

antimony, 180. 

arsenum, 166. 

ethyl, 402. 

iron, 148. 

phosphorus, 329. 

potassium, 77, 270. 

volumetric estimation of, 
643. 

silver, 220, 271. 

sodium, 270. 

sulphur, 304. 
Bromides, 270. 

analytical reactions of, 271. 

quantitative analysis of, 678. 

separation of, from chlorides 
and iodides, 276. 
Bromine, 270. 

analytical separation of, 276. 

derivation of word, 33. 

its analogy to chlorine and 
iodine, 273, 278. 

solution of, 271. 

volumetric estimation of, free, 
678. 

solution of, 658. 
Bromum, 269. 

impurities in, 711. 
Bronze, 241. 

aluminium, 138. 

coinage, 191. 
Bronzing-powder, 244. 
Broom-tops, 542. 
Brown coloring-matters, 556. 

haematite, 142, 153. 

rosin, 423. 

sugar, 469. 
Brucia, 528. 
Brucine, 528. 

distinction from morphine, 529. 
Brunswick green, 177. 



Bryoidin, 426. 
Bryonin, 501. 
Bryonia alba, 501. 

dioica, 501. 
Buchu, 416. 

oil of, 416. 
Buckthorn green, 556. 

juice, 502. 
"Bumping," 282. 
Bunsen's gas-burners, 23. 

valve, 652. 
Burdock, 509. 
Burette, Muhr's, 627. 
Burgundy pitch, 425. 
Burners, gas, 17, 23. 
Burnett's disinfecting fluid, 132. 
Burnt ochre, 555. 

sugar, 471. 

umber, 556. 
Butane, 397. 
Butea frondosa, 359. 
Butter, 463, 546. 

of antimony, 180. 

of cacao, 462. 

of cocoa, 462. 

of kokum, 462. 

of orris, 418. 
Butyl-chloral, 488. 
hydras, 488. 
hydrate, 488. 

sulphocyanate, 415. 
Butylene, 408. 
Butylic alcohol, 364, 449. 
Butyrate of ethyl, 407. 
Butyrates, 364. 
Butyric acid, 364, 488. 

aldehyde, 488. 

chlorinated, 488. 
Butyrone, 498. 
Buxine, 533. 
Buxus sempervirens, 533. 
By-products, 201. 

Cabbage-rose petals, 555. 

oil of, 419. 
Cacao-butter, 462. 
Cadaverine, 513. 
Cadmium, 249. 

analytical reactions of, 250. 

derivation of word, 34. 

hydrate, 250. 

iodide, 250. 

oxide of, 250. 

sulphide. 250. 

sulphate, 250. 
Cxsalpinia bonducella, 509. 

brasiliensis, 554. 
Caesium, 726. 
Caffeina, 242. 



INDEX. 



739 



Caffeina, impurities in, 711. 
citrata, 542. 

effervescens, 543. 
Caffeine. 542. 

citrate, 542. 
Cajuput oil, 416. 
Cajuputene, 416. 
Cajuputol, 416. 
Caking coal, 241. 
Calabar bean, 540. 
Calamina prxparata, 134. 
Calamine, 131, 420. 
prepared, 134. 
Calamus, 420. 
Calamus draco, 424. 
Calcic sulphate, phosphate, etc. 

Vide Salts of Calcium. 
Calcii bromidum, 271. 

volumetric estimation of, 

643. 
impurities in, 711. 
carbonas prsecipitatus, 108. 

impurities in, 711. 
chloridi, liquor, 106. 
chloridum, 106. 

impurities in, 711. 
chlorinatss, liquor, 115. 
hydras, 108. 
hypophosphis, 343. 

impurities in, 711. 
phosphas prgecipitatus, 113. 

impurities in, 711. 
sulphas exsiccatus, 106. 

impurities in, 711. 
Calcined magnesia, 122. 
Calcium, 106. 

analytical reactions of, 116. 
and barium, separation from 

magnesium, 126. 
bisulphite, 306. 
bromide, 271. 

volumetric estimation of, 
643. 
carbonate, 106, 108. 

prepared, 113. 
chloride, 106. 
chromate, 117. 
citrate, 324. 
derivation of word, 32. 
flame, 117. 
fluoride, 106. 

in bones, 114. 
gummate, 116. 
hydrate, 108. 
hypochlorite, 114. 
hypophosphite, 343. 

volumetric estimation of, 
654. 
hyposulphite, 303. 



Calcium, in presence of barium and 
magnesium, detection of, 126. 

oxalate, 117, 316. 

oxide, 108. 

phosphate, 106, 114, 327. 

polysulphide, 303. 

quantitative estimation of, 665. 

silicate, 106. 

sulphate, 106, 115. 

sulphide, 115. 

sulphite, 305. 

tartrate, 325. 
Calc-spar, 106. 
Calcis, liquor, 108. 

syrupus, 108. 
Calculi, urinary, 572. 

examination of, 587. 
Calendula officinalis, 509. 
Calendulin, 509. 
Caliche, 286. 
Calomel, 203, 208. 

test for corrosive sublimate in, 
203. 
Calotropis, 509. 
Calumbx, 533. 
Calx, 108. 

impurities in, 711. 

chlorata, 114. 

impurities in, 711. 

sulphur ata, 115. 

impurities in, 711. 
Cambogia, 427. 

impurities in, 711. 
Camphene, 412. 
Camphor laurel, 421. 

mixture, 422. 

oil, 421. 

water, 422. 
Camphor a, 421. 

impurities in, 711. 

officinarum, 421. 
Camphoric acid, 422. 
Camphoronic acid, 422. 
Camphors, 421. 
Cam-wood, 554. 
Canada balsam, 412, 427. 
Canadian hemp, 509. 

turpentine, 412. 
Candle-flame, composition of, 23. 
Canellse cortex, 509. 
Cane-sugar, 469. 
Cannabene, 423. 

hydride of, 423. 
Cannabin, 423. 
Cannabinine, 423. 
Cannabis indica, 423. 

sativa, 423. 
Cantharides, vinegar of, 298. 
Cantharidic acid, 422. 



740 



INDEX. 



Cantharidin, 422. 

Cantharis, 422. 

Caoutchin, 421. * 

Caoutchouc, 420. 

Capacity, unit, 603. 

Capillary, 595. 

Capric acid, 490. 

Caproate of glyceryl, 462. 

Caproic acid, 462, 490. 

Caprylate of glyceryl, 462. 

Caprylic acid, 462. 

Capsaicin, 425, 534. 

Capsicin, 425. 

Capsicine, 425, 534. 

Capsicum, 508, 638. 

Capsicum-fruit, oleoresin of, 425. 

oil, 425. 
Caramel, 471. 
Caraway-fruit, 416. 

oil, 416. 
Carbamate of ammonium, 93. 

ethyl, 489. 
Carbamic acid, 489. 
Carbamide, 489. 
Carbamines, 483, 544 (table). 
Carbazotic acid, 454, 554. 
Carbinols, 436. 
Carbo animalis, 112. 

purificatus, 112. 
impurities in, 711. 

ligni, 113. 
Carbohydrates. 466. 
Carbolates, 454. 
Carbolic acid, 452. 

antidote to, 454. 
Carbon, 30. 

bisulphide, 314. 

combustion of, 30. 

compounds, chemistry of, 383. 

derivation of word, 32. 

disulphide, 314. 

quantitative estimation of, in 
organic compounds, 688, et 
seq. 

tetrachloride, 401. 
Carbonate of ammonium, 93. 
solution of 94. 

barium, 102, 104. 

bismuth, 254. 

calcium, 106, 108. 
prepared, 113. 

iron, 145. 

saccharated, 145. 

lead, 210, 215. 

lithium, 227. 

magnesium, 119, 122. 

potassium, 62. 
acid, 71. 

sodium, 85. 



Carbonate of sodium, acid, 83. 
chemically pure, 628. 
manufacture of, 88, 312. 

strontium, 229. 

zinc, 134, 137. 
Carbonates, 312. 

acidulous radical in, 66, 312. 

analytical reactions of, 314. 

gravimetric estimation of, 683. 

volumetric estimation of alka- 
line, 631. 
Carbonic acid, 31, 312, 489. 

gas, generation of, 72. 

solubility of, in water, 
86. 

anhydride, 312. 

oxide, 341. 
Carbonei disulphidum, 314. 

impurities in, 711. 
Carbonization, 102. 
Carbonyl, 437. 
Carboxyl group, 437, 489. 
Carburetted hydrogen, light, 396. 

heavy, 409. 
Cardamom oil, 416. 

greater, 418. 

lesser, 416. 
Cardamomum, 416. 
Carica papaya, 534, 551. 
Carolina jasmine, 537. 
Carmine, 337. 
Carminic acid, 337. 
Carnallite, 61. 
Carnine, 515. 
Carpaine, 534. 
Carrageen moss, 479. 
Carrotin, 554. 
Carthamin, 555. 
Carthamus tinctorius, 555. 
Carum ajowan, 415. 
Carvene, 416. 
Carvol, 415, 416. 
Caryophylene, 412. 
Caryophyllin, 416. 
Cascara sagrada, 338. 
Cascarilla oil, 417. 
Cascarillse, 417. 
Cascarillin, 509. 
Casein, 546. 

vegetable, 548. 
Cassava, bitter, 473. 
Cassia acutifolia, 501. 

elongata, 501. 

oil, 417. 
Cassix pulpa, 469. 
Cast iron, 142. 
Gastanea, 359. 
Castile soap, 461. 
Castilloa elastica, 420. 



INDEX. 



741 



Castor, 424. 

fiber, 424. 

oil, 464. 
Castoreum, 424. 
Castorin, 424. 
Cataplasma sinapis, 451. 
Catechin, 359. 
Catechu, 359, 556. 

impurities in, 711. 

nigrum, 359. 
Catechuic acid, 359. 
Cathartic acid, 501. 
Cathartogenic acid, 501. 
Cathode, 245. 
Caulophyllum, 509. 
Caustic, 218. 

alcohol, 443. 

lime, 107. 

lunar, 218. 

mitigated, 218. 

points, 218. 

potash, 62. 

soda, 82. 

toughened, 218. 
Cayenne pepper, 534. 
Cedra oil, 416. 
Cedrene, 419. 
Celandine, 534, 541. 
Celestine, 229. 
Cellulin, 479. 
Celluloid, 480. 
Cellulose, 479. 

of starch, 474. 
Celsius's thermometer, 596. 
Cements, 355. 

Centesimal composition, 385. 
Centiare, 604. 

Centigrade thermometer, 596. 
Cephaelis ipecacuanha, 437. 
Cera alba, 451. 

flava, 451. 

impurities in, 711. 
Cerasin, 479. 
Cerasus virginiana, 500. 
Cerates, 589. 
Cerebrin, 546. 
Ceresine, 450. 
Cerevisise fermentum, 439. 
Cerii oxalas, 236. 

impurities in, 712. 
Cerite, 230. 
Cerium, 230. 

derivation of word, 34. 

oxalate, 230. 
Ceroleine, 450. 
Cerotic acid, 399, 489, 490. 
Ceryl cerotate, 450. 
Cerylic alcohol, 450. 
Cetaceum, 450. 
32* 



Cetine, 450. 
Cetraria, 338, 476. 
Cetraric acid, 338. 
Cetyl hydrate, 450. 
palmitate, 450. 
Cetylic alcohol, 450. 
Cevadilla, 543. 
Cevadilline, 543. 
Cevadine, 539, 543. 
Ceylon " moss," 479. 
Chalcedony, 354. 
Chalk, 106. 

French, 557. 
precipitated, 109. 
prepared, 111. 
stones, 589. 
Chalybeate water, 142. 
Chameleon, mineral, 232. 
Chamomile oil, 415. 
Char, 102. 
Charas, 424. 
Charcoal, 30. 
animal, 112. 

decolorizing power of, 112. 
wood, 113. 
Charles's law, 53. 
Charta potassii nitratis, 286. 

sinapis, 451. 
Chartreuse, 441. 
Chaulmugra, 510. 
Chavica officinarum, 541. 
Chavicic acid, 541. 
Cheese, 546. ' 

poison, 513, 571. 
Chelerythrine, 534. 
Chelidonic acid, 534. 
Chelidonine, 534. 
Chelidonium, 534, 541. 
Chemical action, illustration of, by 
symbols, 41. 

definition of, 35, 57. 
afl&nity, 38. 
combination, laws of, 59. 

by volume, laws of, 53, et 

seq. 
by weight, laws of, 47, et seq. 
different from mechanical, 
31, 36. 
compound, 31. 

definition of, 58. 
diagrams, 46, 47, 64, 65. 
equations, 47, 63. 

definition of, 58. 
force, 38, et seq. 

conditions for the manifes- 
tation of, 40. 
its relations to heat and 
electricity, 623. 
formula, 58. 



742 



INDEX. 



Chemical formulae, 42. 

notation, 41, 46. 

philosophy, principles of, 35, et 
seq. 

preparations of the British 
Pharmacopoeia, 589. 

reagents, xiii. 

symbol, definition of, 58. 

symbols, 41. 

toxicology, 561. 
Chemicals, lists of, xiv. 
Chemism, 38. 

Chemist and Druggist, 14. 
Chemistry, art of, 13. 

definition of, 57. 

derivation of the word, 14. 

inorganic, 383. 

object of, 14. 

of carbon compounds, 383. 

organic, 383. 

science of, 14. 
Chemists, analytical, 14. 

manufacturing, 14. 

pharmaceutical, 14. 
Chenopodium, 420. 
Cherry-laurel water, 500. 

sugar in, 467. 

tree gum, 479. 

wild black, 500. 
Chestnut brown, 556. 
Chian turpentine, 413. 
Chicory, 476. 
Chili saltpetre, 286. ' 

nitre, 286. 
Chimaphila umbellata, 501. 
China clay, 355. 
Chinese green, 556. 

red, 554. 

wax, 450. 

white, 557. 

yellow, 553. 
Chinoidin, 526. 
Chinoline, 514. 
Chirata, 351. 
Cbiratin, 351. 
Chiratogenin, 351. 
Chiretta, 351. 
Chloral, 400, 485. 

alcoholates, 486, 488. 

butyl, 488. 

croton, 488. 

impurities in, 712. 

hydrate, 486. 

estimation of, 487. 
Chlorate of potassium, 293. 

preparation of oxygen from, 
16. 

of sodium, 294. 
Chlorates, 293. 



Chlorates, analytical reaction of, 295. 
Chloric acid, 114, 292. 
Chloride of acetyl, 396. 
aluminium, 138. 
ammonium, 91. 
antimony, 180. 
arsenum, 166. 
barium, 103. 
boron, 333. 
calcium, 106. 

removal of iron from, 106. 
chromium, 238. 
ethylene, 411. 
ethylidene, 411. 
gold, 246. 
iridium, 571. 
iron, 148, 149. 
lead, 214. 
lime, 114. 
magnesium, 118. 
manganese, 231. 
mercuric-ammonium, 206. 
mercurous-ammonium, 207, 208. 
mercury, 201. 
methyl, 399. 
palladium, 571. 

platinum and ammonium, 99, 
247. 

and lithium, 228. 

and potassium, 79, 247. 

and sodium, 247. 
silicon, 355. 
silver, 217. 
sulphur, 304. 
tin, 242. 

solution of, 242. 
zinc, 132. 
Chlorides, 265. 

estimation of, 677. 

separation of, from bromides 

and iodides, 276. 
tests for, 268. 
Chlorinated butyric aldehyde, 488. 
lime, 114. 

volumetric estimation of, 
657. 
soda, solution of, 87. 

volumetric estimation of, 
657. 
Chlorine, 27, 267. 
acids, 295. 

as a disinfectant, 29. 
bleaching by, 29. 
collection of, 28. 
derivation of word, 32. 
inhalation of, 29. 
its analogy to bromine and 

iodine, 272, 278. 
liquid, 268. 



INDEX. 



743 



Chlorine, preparation of, 27. 
properties of, 28. 
relative weight of, 29. 
solubility in water, 28. 
the active agent in bleaching- 

powder, 29. 
volumetric estimation of, 656. 
water, 28, 267. 
Chlorochromic anhydride, 240, 277. 
Chloroform, 399. 

impurities in, 712. 
-water, 401. 
Chloronitric gas, 289. 
Chloronitrous gas, 289. 
Chlorophyll, 553, 556. 
Chlorous acid, 295. 
Chocolate, 462. 
Cholesterin, 460, 589. 
Choline, 513, 552. 
Chondrine, 549. 
Chondrus crispus, 479. 
Christmas rose, 505. 
Chromate of ammonium, 238. 
barium, 105. 
calcium, 117. 
lead, 214. 
potassium, red, 238. 

standard solution of, 
648. 
yellow, 105, 238. 

and ammonium, 105. 
of silver, 220. 
Chromates, 238. 

analytical reactions of, 240. 
Chromes, 215. 
Chrome-alum, 139, 238. 
ironstone, 238. 
-orange, 215. 
-red, 215, 554. 
-yellow, 215, 553. 
Chromic acid, 238. 

anhydrous, 239. 
anhydride, 239. 
hydrate, 240. 
salts, 239. 
Chromium, 238. 

analytical reactions of, 240. 

chloride, 238. 

derivation of word, 34. 

oxide of, 238. 

separation of, from aluminium 

and iron, 241. 
sulphate, 238. 
Chromogens in urine, 578. 
Chromous salts, 238. 
Chromule, 556. 
Chrysarobin, 338. 
Chrysarobinum, 338. 
Chrysatropic acid, 532. 



Chrysophan, 338. 
Chrysophanic acid, 338, 434. 
Churras, 424. 
Chyme, 551. 
Cicuta virosa, 417. 
Cicutine, 536. 
Cider, 441. 

Cimicifuga racemosa, 509. 
Cimicifugse rhizoma, 509. 
Cimicifugin, 509. 
Cinchamidine, 526. 
Cinchona calisaya, 521. 

land folia, 521. 

officinalis, 521. 
Cinchona succirubra, 521. 
Cinchonse rubrx cortex, 521. 
Cinchonicine, 526. 
Cinchonidinse, 526. 

impurities in, 712. 

sulphates, 526. 

impurities in, 712. 
Cinchonidine, 526. 

impurities in, 712. 
Cinchonina, 525. 
Cinchoninse sulphas, 526. 

impurities in, 712. 
Ciuchonine, 525. 
Cinchovatine, 526. 
Cinnabar, 195, 554. 
Cinnamein, 495. 
Cinnamene, 495. 
Ciunamic acid, 337, 494. 

alcohol, 495. 

aldehyde, 417. 

series of acids, 494. 
Cinnamol, 495. 
Cinnamon-bark, 417. 
Cinnamon oil, 417. 
Cinnamyl cinnamate, 495. 
Cissampeline, 533. 
Cissampelos pareira, 533. 
Citrate of ammonium, 95. 

bismuth, 254. 

ammonium, 254. 

caffeine, 542. 

calcium, 325. 

iron and quinine, 155, 522. 

lithium, 227. 

magnesium, 122. 

nicotine, 539. 

potassium, 73. 

volumetric estimation of, 
632. 

quinine, 523. 

silver, 326. 

strychnine, 527. 
Citrate, 323. 

analytical reactions of, 325. 
Citrenes, 412. 



744 



INDEX. 



Citric acid, 323, 498. 

action of heat on, 324. 
saturating power of, 325. 
volumetric estimation of, 
637. 
Citron oil, 416. 
Citronella oil, 417. 
Citron ellol, 417. 
Citro-tartrate of sodium, 88. 
Citrus, 416. 

bergamia, 323. 
Classification, 102, 123, 257. 393. 
Clausius's theory, 24. 
Claviceps purpurea, 424. 
Clay, 138, 354. 

fire-, 202. 

ironstone, 142. 
Cloves, oil of, 416. 
Club-moss, 464. 
Coal, 241. 

brasses, 142. 

gas, 408, 454. 

for balloons, 24. 
Coal-tar, products of, 453, 557. 

colors, 557. 
Cobalt, 234. 

analytical reactions of, 235. 

arsenide, 235. 

blue, 555. 

derivation of word, 34. 

glance, 235. 

hydrate, 235. 

oxide, 235, 555. 

separation of, from nickel, 237. 

sulphate, 235. 

sulphide, 235. 
Cobaltic ultramarine, 555. 
Cobalticyanide of potassium, 235. 

nickel, 237. 
Coca, 534. 
Cocaidine, 534. 
Cocainse hydrochloras, 534. 

impurities in, 712. 
Cocaine, 534. 
Cocamine, 534. 
Coccerin, 238. 
Cocculus indicus, 506. 
Coccus, 337. 

impurities in, 712. 

cacti, 337. 

ilicis, 182. 
Cochineal, 337, 555. 
Cocoa, 462, 543. 

nibs, 462. 

nut, 462. 
oil, 462. 
Cocos nucifera, 462. 
Codamine, 518. 
Codeina, 517. 



Codeina, impurities in, 712. 

Codeine, 517, 520. 

Cod-liver oil, 463. 

Coffee, 542. 

Cohesion, 57. 

Coinage, copper, 191, 617. 

gold, 245, 617. 

silver, 216, 617. 
Coke, 30. 
Colchici cormus, 535. 

semini, 535. 
Colchicein, 535. 
Colchicin, 535. 
Colchicine, 535. 
Colchicum autumnale, 535. 
Colcothar, 153, 555. "* 
Collection of gases, 16, 17. 
Collidine, 513, 532. 
Collin, 705. 
Collodion, 480. 

blistering, 480. 

flexible, 480. 
Collodium, 480. 

cantharidatum, 480. 

flexile, 480. 

vesicans, 480. 
Colloid bodies, 705. 
Colocynthidis pulpa, 502. 
Colocynthin, 502. 
Colophene, 413. 
Colopholic acid, 423. 
Colophonic acid, 423. 

hydrate, 423. 
Colophonine, 423. 
Coloring-matters, 553. 
Combination, chemical, by weight, 
47. 

by volume, 52, et seq. 
Combining proportions, 50, 198, 

592, et seq. 
Combustible, 23. 
Combustion, 23. 

analysis for carbon and hydro- 
gen, 688, et seq. 
for nitrogen, 691. 

definition of, 58. 

spontaneous, 158. 

supporters of, 23. 
Composition of atmosphere, 27. 

bismuth salts, 252, 254. 

centesimal, 385. 

empirical, 385. 

molecular, 386, 

oils and fats, 459. 

organic compounds, 384. 
Compounds, chemical, 31. 
definition of, 58. 
different from mechanical, 
36. 



INDEX. 



745 



Compounds, 36. 

of the elements, 60. 
Conchinine, 524. 
Concrete oil of mangosteen, 463. 
Condensation, 128. 
Condenser, 128. 
Condensing-tub, 128. 

worm, 128. 
Confections, 470. 
Conhydrine, 536. 
Conia, 536. 
Conicine, 536. 
Conii folia, 536. 
Conine, 532, 536. 
Conium, 536. 

maculatum, 536. 
Conqninine, 524. 
Constant proportions, law of, 48. 
Constant white, 557. 
Constitution. See also " Structure." 
Constitution as indicated by — 

chemical "periodicity," 380. 

properties, 387, 395. 

density of gases and vapors, 
53, 55, 619. 

electricity, etc., 623. 

isomorphism, 55. 

specific heat, 622. 

substitution, 394. 
Constitution of alkaloids, 510, 
513. 

benzene series, 432. 

bleaching powder, 114. 

magnesium carbonate, 121. 

matter, 42, 130. 

molecular, 130, 138, 139, 193, 
386, 390. 

organic compounds, 387, 393, 
396. 

of salts, 66, 87, 124, 286, 299, 
378, 387, 390, 396, 513. 
Constitutional formula, 386. 
Construction of formulae, 46, 389, 

392, 396. 
Convolvulin, 505. 
Convolvulinol, 505. 
Convolvulus scammonia, 508. 
Conylia, 536. 
Copaiba, 426. 

impurities in, 712. 
Copaiva, 426. 

oil, 417. 
Copaivaol, 426. 
Copaivic acid, 426. 
Copal, 424. 
Copper, 190. 

acetate, 192. 

ammonio - sulphate, 178, 193, 
207. 



Copper, analytical reactions of, 192. 

antidotes to, 194. 

arsenate, 177. 

arsenite, 177, 194. 

black oxide of, 192. 

blue, 555. 

carbonate, 190. 

coinage, 191. 

derivation of word, 33. 

detection of arsenum in, 173. 

ferrocyanide, 194. 

flame, 194. 

foil, 192. 

hydrate, 194. 

hydride, 345. 

in organic mixtures, detection 
of, 564. 

iodide, 276. 

melting-point of, 599. 

metallic, 190. 

nitrate, 192. 

oxide, 191. 

oxyacetate, 192. 

pyrites, 190. 

quantitative estimation of, 671. 

quanti valence of, 191. 

subacetate, 192. 

sulphate, 192. 

anhydrous, 192. 

sulphide, 192. 

zinc couple, 679. 
Copperas, blue, 144, 192. 

green, 144. 
Coptis-root, 533. 
Coriander oil, 417. 
Cork, specific gravity of, 618. 

borers, 16. 
Cornic acid, 338. 
Cornin, 338. 
Cornutene, 424. 
Corpse fat, 548. 

Correction of the volume of a gas 
for pressure, 619. 

for temperature, 619. 
Correlation of force, 38. 

matter, 38. 
Corrosive sublimate, 201. 

test for, in calomel, 203. 
Cortex pruni serotinse, 500. 
Corydaline, 536. 
Corydalis, 536. 
Cotarnine, 518. 
Coto-bark, 502. 
Cotoin, 502. 
Cotton -seed oil in olive oil, 459. 

cake, 515. 
Cotton-wool, 479. 
Couch-grass, 511.' 
Coumarin, 494. 



746 



INDEX. 



Cowbane, 417. 
Cowhage, 242. 
Cow's milk, 546. 
Cranesbill, 360. 
Cream, 547. 

of tartar, 62, 80, 318. 
soluble, 334. 
Creasol, 453. 
Creasote, 453. 
Creasotum, 453. 

impurities in, 712. 
Creatine, 512. 
Creatinine, 512. 
Cremnitz white, 557. 
Cresol, 453, 455. 
Cresotic acid, 493. 
Cresylic acid, 453. 
Greta, 111. 

prseparata, 111. 

impurities in, 712. 
Crini radix, 508. 
Crinum asiaticum, 508. 
Crith, 621. 
Crocetin, 554. 
Crocin, 554. 
Crocus (mineral), 153. 

(vegetable), 554. 

impurities in, 712. 

of antimony, 180. 
Crocus sativus, 554. 
Croton chloral, 488. 

hydrate, 488. 

oil, 463. 
Crotonic acid, 491. 
Crotonylene, 411. 
Crucibles, 70, 355. 
Crude antimony, 180. 

potashes, 62. 
Cr urn's test for manganese, 234. 
Cruso-creatinine, 513. 
Cryohydrates, 81. 
Cryolite, 376. 
Cryptopine, 518. 
Crystallization, water of, 86. 

fractional, 78, 378. 
Crystalloid bodies, 705. 
Cubeb pepper, 541. 
Cubeba, 541. 
Cubebene, 417. 
Cubebin, 541. 
Cubebs, oil of, 417. 

oleo-resin, 428. 
Cubic inches in a gallon, 621. 

nitre, 286. 
Cuca. See Coca. 
Cucurbita pepo, 510. 
Cudbear, 555. 
Culver's root, 510. 
Cumin, 417. 



Cuminic acid, 417. 

Cuminum cyminum, 417. 

Cummin, 417. 

Cupel, 676. 

Cupellation, estimation of silver 

by, 676. 
Cupr-diammon - diammonium, sul- 
phate of, 207. 
Cuprea-bark„ 521. 
Cupreine, 526. 
Cupri sulphas, 192. 

impurities, 712. 

nitras, 192. 
Cupric arsenite, 177, 194. 

compounds, 191. 

ferrocyanide, 194. 

hydrate, 194. 

nitrate, 192. 

oxide, 191. 

sulphate, 192. 

sulphide, 192. 
Cuprous hydride, 345. 

iodide, 191. 

oxide, 191, 468. 
Cuprum, 190. 
Curacoa, 441. 
Curari, 528. 
Curarine, 528. 
Curcuma longa, 420, 554. 
Curcumin, 554. 
Curd soap, 461. 
Curds, 546. 

and whey, 471, 546. 
Currants, sugar in, 467. 
Curry powder, odor and flavor of, 

420. 
Cusparise cortex, 536. 
Cusparidine, 536. 
Cusparine, 536. 
Cusso, 424. 
Cutch, 359. 
Cyanates, 338. 
Cyanic acid, 338. 
Cyanide of allyl, 451. 

mercury, 280. 

nickel, 237. 

potassium, 280. 

silver, 220, 283. 
Cyanides, 280. 

analytical reactions of metallic, 
283. 

antidote to, 283. 

double, 280. 

quantitative estimation of, 641, 
678. 
Cyanogen, 162, 279. 
Cyanurets. Vide Cyanides, 
i Cyder. See Cider. 
I Cymene, 415, 417, 429, 432. 



INDEX. 



747 



Cymol, 415. 
Cypripedin, 510. 
Cypripedium pubescens, 510. 
Cystin, 581. 
Cytisine, 436. 

Dahlia, 476. 

Dalleiochin, 523. 

Dalton's atomic theory, 51. 

laws, 47, 48, 49. 
Dambose, 469. 
Dandelion, 476. 
Daphne laureola, 425. 

mezereum, 425, 502. 
Daphnetin, 502. 
Daphnin, 502. 
Datura alba, 538. 
Daturia, or Daturin, 538. 
Daughlisk's bread, 470. 
Davy safety-lamp, 24. 
Deadly nightshade, 531. 
Decane, 398. 
Decantation, 110. 
Decimal coinage, 605. 

weights, 602. 
Decoction, 589. 

Decolorizing power of animal char- 
coal, 113. 
Decrepitation, 372. 
Decylene alcohol, 452. 
Definition of an atom, 57. 

atomic weights, 59. 

a chemical compound, 58. 
equation or diagram, 58. 
formula, 58. 
symbol, 58. 

a gas, 58. 

a liquid, 58. 

a mixture, 57. 

a molecule, 57. 

a solid, 58. 

an element, 57. 

chemical action, 57. 
force, 57. 

chemistry, 57. 

combustion, 58. 

law of diffusion, 58. 

molecular weights, 59. 

quantivalence of atoms, 59. 
Deflagrating flux, 377. 
Deflagration, 75. 
Deliquescence, 89. 
Delphine, Delphinine, or Delphia, 

536. 
Delphinium staphysagri, 536. 
Density, 614. 

of vapors, 619. 
Dentifrices, action of, 242. 
Deodorizers, 29. 



Deodorizing liquid, 132. 

power of animal charcoal, 113. 
Deoxidizers, 645. 
Deposits, urinary, 579. 
Derivations of names of elements, 

32, et seq. 
Desiccation, 661, 687. 
Desiccators, 661. 
Destructive distillation, 129. 
Detonation, 75. 
De Valangin's solution, 168. 
Dextrin, 476. 
Dextrogyrate, 469. 
Dextroracemic acid, 320. 
Dextrose, 467. 
Dextrotartaric acid, 320. 
Dhak tree, 359. 
Dhatura, 538. 
Diabetic urine, 575. 
Diacid alcohols, 456. 
Diamide, 515. 
Dicarbonyl benzene, 521. 
Diagram, chemical definition of, 63. 
Diagrams, chemical, 42, 63. 
Dialysate, 705. 
Dialysis, 705. 
Dialytic iron, 705. 
Dialyzed iron, 160, 705. 
Diamines, 512. 
Diamond, 30. 
Diaphragms, 71. 
Diastase. 477. 

action of, upon starch, 477. 
Diazo, 513. 
Diazobenzene, 513. 
Dibasic acids, 264, 495. 
Dibasylous radicals, 264. 
Dibromethane, 409. 
Dicentra formosa, 536. 
Dichloromenthane, 399. 
Dichloromethylbenzene, 432. 
Dichopsis gutta, 420. 
Didymium, 230. 
Dietetics, 15. 
Diethyl, 397. 
Diethylamine, 511. 
Diethylsulphon - dimethylmethane, 

446. 
Diffusate, 705. 
Diffusion of gases, 24. 

law of, definition of, 24, 58. 
Digallic acid, 357. 
Digitalein, 503. 
Digitalin, 502. 
Digitaliretin, 502. 
Digitalis, 502. 

folia, 502. 
Digitin, 503. 
Digitogenin, 503. 



748 



INDEX. 



Digitonin, 503. 
Digitoxin, 503. 
Dihydric alcohols, 409, 456. 
Dihydroxyacetic acid, 490. 
Dihydroxybenzoic acid, 493. 
Dihydroxybutyric acid, 490. 
Dihydroxyl benzenes, 455. 

derivatives of the hydrocar- 
bons, 456. 
Dihydroxypropionic acid, 490. 
Dihydroxysuccinic acid, 496. 
Di-iodo-paraphenol-sulphonic acid, 

445. 
Di-iodosalicylic acid, 493. 
Diketone, 521. 
Dill oil, 415. 
Dipentene, 412. 
Dirnercuric-ammonium, 207. 
Dimethyl, 397. 

Dimethyl-ethyl-carbonol, 450. 
Dinitrocellulin, 479. 
Diosphenol, 416. 
Diospyri fructus, 360. 
Diospyros embryopteris, 360. 
Dipterocarpi balsamum, 426. 
Dipterocarpus Isevis, 426. 

turbinatus, 426. 
Disinfectant, chlorine as a, 29. 
Disinfectants, 29. 
Disinfecting fluid, Burnett's, 132. 
carbolic acid, 453. 
Condy's, 78, 232. 

powder, 114. 

solution, 114. 
Dissociation, 622. 
Distillation, 127. 

destructive, 129. 

dry, 129. 

fractional, 378, 439. 
Distilled water, 129. 
Disulphide of carbon, 314. 
Dita, 537. 
Ditain, 537. 
Ditamine, 537. 
Dithionic acid, 346. 
Dock, 338. 
Dolomite, 118. 
Donovan's solution, 167. 
Dorema ammoniacum, 427. 
Double chloride of aluminium and 
sodium, 139. 

cyanides, 280. 

salts, 79, 139. 
Doundake bark, 424. 
Dover's powder, 537. 
Draconyl, 495. 
Dragon's blood, 424. 
Dried alum, 140. 
Drops, 608. 



Dry distillation, 129. 
Drying apparatus, 112. 

in vacuo, 112. 

oils, 463. 

precipitates, 112. 
Dryobalanops aromatica, 421. 
Duboisia myoporoides, 538. 
Duboisine, 538. 
Dulcamara, 541. 
Dulcamarin, 541. 
Dulcin, 431. 
Dulcite, 465. 

Dulong and Petit's law, 623. 
Dutch camphor, 421. 

liquid, 411. 
Dyads, 123. 

Dyeing by mordants, 140. 
Dyer's saflron, 555. 
Dynamic electricity, production of, 

132. 
Dynamicity, 56. 
Dynamite. 458. 

Earth, bone-, 112, 327. 
Earthenware, 354. 
Earth-nut oil, 464. 
Earth pitch, 427. 
Earths, alkaline, 127. 
Eau de Cologne, 405. 
Eau de Javelle, 88. 
Ebonite, 420. 
Ebullition, 282. 
Ecballii fructus, 503. 
Ecboline, 424. 
Ecgonine, 534. 
Echites scholaris, 537. 
Effervescing citrate of magnesia, 
88, 121. 

citro-tartrate of sodium, 88. 

soda-water, 86. 

solution of potash, 72. 

sulphate of magnesium, 119 

tart, soda powder, 321. 
Efflorescence, 89. 
Egg, oil of yelk of, 545. 

white of, 544. 
Elseometer, 616. 
Elseoptens, 413. 
Elaidic acid, 491. 
Elastica, 421. 
Elaterin, 503. 
Elaterium, 503. 

impurities in, 503, 712. 
Elder-flower oil, 419. 
Elecampane, 418. 
Electric amalgam, 196. 
Electricity, production of dynamic, 
132. 

related to chemical action, 623. 



. 



INDEX. 



749 



Electrolysis, 22, 623. 
Element, definition of, 57. 
Elements, 13, 15, 32, 380. 

and their compounds, 60. 

classification of, according to 
analogy, 102. 

etymology of names of, 32, et 
seq. 

metallic, 15. 

non-metallic, 16. 

of medical or pharmaceutical 
interest, 15. 

quanti valence of, 123. 

symbols of, 32, 58. 

atomic values, and weights 

of the, 725. 
of, and derivation of name 
of, 32, et seq. 
Elemi, 426. 
Elutriation, 134. 

fractional, 378. 
Emerald green, 536. 
Emetine, 537. 
Emodin, 338. 
Empirical formulae, 385. 

composition, 385. 
Emplastra, 213, 423. 
Emplastrum menthol, 418. 

plumbi, 213. 
iodidi, 213. 

saponis fuscum, 298. 
Emulsin, 500. 
Emulsions, 428. 
Enemas, 589. 
English red, 555. 

blue, 555. 
Enzymes, 441. 
Eosin, 434. 
Epsom salt, 118. 

Equation, chemical definition of, 58. 
Equations, 46, 64. 
Equisetic acid, 324. 
Equivalence, 56. 
Equivalents, 726. 
Erbium, 725. 
Ergosterin, 424. 
Ergot, 424. 
Ergota, 424. 
Ergotin, 424. 
Ergotine, 424. 
Ergotinic acid, 424. 
Ergotinine, 424. 
Ergotinum, 424. 
Ericolin, 501. 
Erlangen blue, 556. 
Error in experiment, 693. 
Erucic acid, 464. 
Erythrite, 465, 496. 
Erythroretine, 338. 



Erythroxylon coca, 534. 
Esculin. See iEsculin. 
Eseridine, 540. 
Eserine, 540. 
Essence of aniseed, 414. 

apple, 407. 

ginger, 420. 

greengage, 407. 

melon, 407. 

mirbane, 430. 

mulberry, 407. 

peppermint, 414. 

pineapple, 407. 

quince, 407. 
Essences, 415. 
Essentia anisi, 414. 

menthse piperita, 414. 
Essential oils. See Oils. 
Ester, 484, 
Etching, 343. 
Ethal, 450. 
Ethane, 397. 

substitution products of, 402. 
Ether, 446. 

acetic, 300, 406. 

hydrobromic, 402. 

nitrous, 351. 

petroleum, 398. 
Ethereal salts, 407, 483. 
Ethers, 444, 484. 

mixed, 447. 

sulphur, 447. 
Ethiop's mineral, 208. 
Ethyl, acetate, 300, 406 

bromide, 402. 

butyrate, 407. 

carbamate, 489. 

formic acid, 488. 

group, 392. 

hydrate, 436. 

hydride, 397. 

hydrogen sulphate, 439, 447. 

hydroxylamine, 515. 

iodide, 402. 

nitrite, 403. 

oenanthylate, 407. 

oxide, 445. 

pelargonate, 407. 

sebacate, 407. 

suberate, 407. 

sulphuric acid, 447. 
Ethylamine, 511. 
Ethylate of sodium, 443. 
Ethylene, 408. 

chloride, 411. 

dibromide, 409. 

hydrate, 436. 

sulphate, 409. 
Ethylic acid, 490. 



750 



INDEX. 



Ethylic alcohol, 439. 

bromide, 402. 

iodide, 402. 

series of alcohols, 436. 
Ethylidene, chloride of, 411. 

compounds, 489. 

lactic acid, 489. 
Ethylsulphonic acid, 445. 
Ethylsulphuric acid, 447. 
Etymology of names of elements, 

32. 
Eucalypti gummi, 418. 

rostrata, 418. 
Eucalyptol, 418. 

impurities in, 712. 
Eucalyptus oil, 417. 

var., 359. 
Eucalyptus globulus, 417. 
Euchlorine, 296. 
Eudiometry, 568. 
Eugenic acid, 416. 
Eugenin, 416. 
Eugenol, 416. 
Euodic aldehyde, 419. 
Euonymi cortex, 509. 
Euonymin, 510. 
Euonymus atropurpureus, 510. 
Eupatorium perfoliatum, 509. 
Euphorbium, 427. 
Euphorbon, 427. 
Euxanthate of magnesium, 554. 
Evaporation, 71. 
Everett's yellow salt, 282. 
Ewe's milk, 548. 

Examinations of the Pharmaceuti- 
cal Society of Great Britain, 
14. Vide prefatory matter, 
xi. 
Experimental error, 693. 
Explosions of gas, 22. 
Extract of malt, 478. 
Extracts, 589. 
Eztractum cinchonas liquidum, 694. 

euonymi siccum, 509. 

glycyrrhizse purum, 504. 
fluidum, 504. 

hamamelidis liquidum, 509. 

nucis vomicx, 700. 

saturni, 212. 

Face-rouge, 337. 

Fseces, 573. 

Fahrenheit's thermometer, 596. 

Farina tritici, 473. 

Fats and oils, composition of, 459. 

Fats, etc., analysis of, 706. 

solid, 462. 

to determine the melting-point 
of, 597. 



Fatty acids, 462. 
bodies, 458. 

series of, 395. 
Fehling's solution, 701. 
Fel bovinum purificatum, 532. 
Fel bovis, 532. 
Felspar, 355, 376. 
Fenchene, 412. 
Fennel oil, 418. 
Fenugreek, 443. 
Fer reduit, 158. 
Fermentation, 440. 
acetic, 440. 
alcoholic, 440. 
ammoniacal, 440. 
butyric, 440. 

by soluble albumenoids, 440. 
lactic, 440. 
mannitic, 440. 
putrefactive, 440. 
viscous, 440. 
Ferments, 441. 
Ferrate of potassium, 143. 
Ferri acetatis, liquor, 154. 
fortior, 154. 
tinctura, 154. 
arsenas, 146, 170. 
carbonas, 145, 153. 
saccharatus, 145. 

impurities in, 712. 
citras, 154. 

liquor, 154. 
et ammonii citras, 45. 

impurities in, 712. 
quantitative estima- 
tion of iron in, 669. 
et ammonii sulphas, 140. 

impurities iu, 712. 
et ammonii tartras, 157. 
et potassii tartras, 156. 

impurities in, 712. 
et quininse citras, 156, 522. 
impurities in, 712. 
quantitative estima- 
tion of quinine in, 
697. 
et quinina citras solubilis, 155. 

impurities in, 713. 
et strychninse citras, 154. 

impurities in, 713. 
hypophosphis, 344. 

impurities in, 713. 
iodidum saccharatum, 148. 

impurities in, 713. 
lactas, 348. 

impurities in, 713. 
oxidum hydratum, 151. 
perchloridi, liquor, 150. 
pernitratis, liquor, 158. 



INDEX. 



751 






Ferri peroxidum hydratum, 151. 
persulphatis, liquor, 151. 
phosphas solubilis, 146, 157. 

impurities in, 712. 
pulvis, 158. 
subcarbonas, 145, 153. 
sulphas granulatus, 144. 
impurities in, 713. 
exsiccatus, 144. 
granulata. 144. 

impurities in, 713. 
valerianas, 363. 

impurities in, 713. 
Ferric acetate, 154, 300. 
aceto-nitrate, 158. 
benzoate, 337. 
chloride, 148. 

hydrous, 149. 
citrate, 155. 
hydrate, 151. 
hypophosphite, 344. 
vol. est. of, 654. 
iodate, 296. 
nitrate, 157. 
oxide, 152, 154. 

separated from phosphates 
and oxalates, 375. 
oxyhydrate, 157. 
oxyiodate, 296. 
oxysulphate, 145. 
phosphate, 157, 331. 
salts, 143, et seq. 

analytical reactions of, 161. 
sulphate, 150. 
sulphocyanate, 162, 356. 
valerianate, 363. 
Ferricyanide of potassium, 341. 
Ferricyanides, 341. 
Ferricyanogen, 162, 342. 
Ferrocyanide of potassium, 280, 
341. 
of zinc, 137. 
Ferrocyanides, 341. 
Ferrocyanogen, 162, 341. 
Ferrous arsenate, 146, 170. 
ammonium sulphate, 649. 
arsenate, vol. est. of, 650. 
bromide, 148. 
carbonate, 145. 

vol. est. of, 650. 
chloride, 149. 

anhydrous, 149. 
citrate, 157. 
hydrate, 161. 
iodide, 147. 
lactate, 348. 
phosphate, 146. 

vol. est. of, 651. 
salts, 144, et seq. 



Ferrous salts, analytical reactions 
of, 160. 

sulphate, 144. 

vol. est. of, 650, 653. 

sulphide, 31, 148, 160, 162. 

tartrate, 157. 
Ferrum, 142. 

reduetum, 158, 669. 

impurities in, 713. 

tartaratum, 154, 156. 
est. of iron in, 669. 
Ferula Narthex, 427. 
Ferulaic acid, 427. 
Fibrin, 545. 

vegetable, 548. 
Ficus, 467. 

elastica, 420. 
Fig, 467. 
Filicic acid, 464. 
Filix mas, 464. 
Filter, to dry, 660. 
Filtering-paper, 109. 
Filters, 109. 
Filtrate, 125. 
Fine gold, 245. 
Fire-clay, 202. 
Fire-damp, 396. 
Fir wool, 413. 

oil, 413. 
Fish-poison, 513. 
Fixed oils, 463. 

and volatile oils, difference 
between, 463. 
Flag, blue, 509. 
Flake white, 557. 
Flame, oxidizing, 135. 

reducing, 136. 

structure of, 23. 
Flare, 462. 
Flashing-point, 413. 
Flaxseed, 479. 

Fleitmann's test for arsenum, 175. 
Flexible collodion, 480. 
Flint, 354. 
Flores zinci, 135. 
Flour, 472. 

Flowers of sulphur, 301. 
"Fluid magnesia,'' 120. 
Flurorescin, 434. 
Fluoric acid, 342. 
Fluoride of boron, 333. 

calcium, 106. 

in bones, 112. 

lithium, 227. 

silicon, 342. 
Fluorides, 342. 
Fluorine, 343. 

derivation of word, 33. 
Fluor-spar, 106, 342. 



752 



INDEX. 



Fceniculum, 418. 
Foil, copper. 191. 

tin, 241. 
Food, analysis of, 706. 

elements of, 548. 

how disposed of in the bodies 
of animals, 548. 
Force, chemical, 37, et seq. 

origin of, 38. 
Formates, 339. 
Formic acid, 339, 484, 490. 
Formica rufa, 339. 

Formula, chemical, definition of, 
58. 

official, 29. 

officinal, 29. 
Formulae, 42, 723. 

constitutional, 386. 

construction of, 56. 

empirical, 386. 

graphic, 138. 

molecular, 55, 386. 

rational, 386. 

structural, 138, 386, 390, 430. 

two-volume, 55, 386. 

typical, 379. 

why used at all, 391. 
Fousel oil, 449. 
Fowler's solution, 168. 
Foxglove, 502. 
Fractional distillation, 378, 439. 

crystallization, 78, 378. 

elutriation, 134, 378. 

fusion, 378. 

lixiviation, 89, 378. 

operations, 378. 

precipitation, 79, 378. 

sifting, 372, 378. 

solution, 89. 

sublimation, 93, 378. 
Frangula, 502. 

bark, 338. 
Frangulin, 338, 503. 
Fructus ptychotis, 415. 
Frankincense, Arabian, 428. 

common, 428. 
Fraxinus ornus, 465. 
Free acids, 367. 

estimated, 636. 
Freezing-mixture, 305. 
French chalk, 557. 

turpentine, 412. 
Fruit-essences, 407. 
Fuchsine, 557. 
Fulminating silver, 219. 

mercury, 219, 
Fume-cupboard, 97. 
Fumerolles, 333. 
Fuming sulphuric acid, 310. 



Funnel-tubes, 21. 

"Fur" in water- vessels, 315. 

Furniture of a laboratory, xiii. 

Furze, 536. 

Fusel oil, 449. 

Fusibility of metals, table of the, 

599. 
Fusible white precipitate, 206. 
Fusing-points of fats, 598. 
Fusion, fractional, 378. 
Fustic, 553. 

Gab tree, 360. 
Gadinine, 513. 
Galactose, 471. 
Galbanum, 427. 
Galena, 210. 

argentiferous, 216. 
Galenical preparations of the 

British Pharmacopoeia, 589. 
Galipea cusparla, 536. 
Galipine, 536. 
Galipot, 423. 
Gall of the ox, 552. 
Galla, 357. 

Gallic acid, 460, 493, 494. 
Gallium, 725. 
Gallon, 668. 

Gallotannic acid; 357, 494. 
Galls, Aleppo, 357. 

English, 357. 
Gall-stones, 589. 
Galvanic test for mercury, 208. 
Galvanized iron, 131. 
Gambier, 359. 
Gamboge, 427. 
Gambogic acid, 427. 
Ganja, 423. 
Garancin, 554. 
Garcinia indica, 463. 

Hanburii, 427. 

oil, 462. 

pictoria, 427. 

purpurea, 463. 
Garcinise purpurea oleum, 463. 
Garden thyme, 417. 
Garlic, essential oil of, 452. 
Gas analysis, 361, 550. 

-burners, 17, 23. 

coal, 408, 454, 557. 

definition of, 59. 

for balloons, coal-, 24. 

lamp, 17. 
Gases and vapors, analysis of, 361. 

collection of, 16, 17. 

correction of the volume of, 619. 
for pressure, 619. 
for temperature, 619. 

diffusion of, 24. 



INDEX. 



753 



Gases, law of solubility of, in water, 
86. 

relation of, to liquids and 
solids, 42. 

specific gravity of, 619. 
Gastric juice, 550. 

artificial, 550. 
Gaultheria procumbens, 407. 
Gaultheric acid, 407. 
Gay-Lussac's law, 52. 
Gelatigenous substances, 549. 
Gelatin, 549. 

sugar, 552. 

tests for, 550. 

vegetable, 479. 
Gelatinum, 555. 
Gelsemine, 537. 
Gelseminic acid, 537. 
Gelseminine, 537. 
Gelsemium, 537. 
Gentian bitter, 503. 
Gentiana lutea, 503. 
Gentianse radix, 503. 
Gentianic acid, 504. 
Gentiogenin, 504. 
Gentiopicrin, 503. 
Gentisic acid, 504. 
Gentisin, 504. 
Geraniol, 418. 
Geranium maculatum, 360. 

oil, 418. 
German silver, 131, 236. 
Gbatti, 479. 
Gin, 441. 
Giugelly oil, 464. 
Ginger, essence of, 420. 

-grass oil, 418. 

oil, 420. 
Gingerol, 534. 
Girdwood. and Eoger's method for 

detecting strychnine, 567. 
Glacial acetic acid, 299. 

phosphoric acid, 330. 
Glass, 355. 

liquid, 355. 

of antimony, 180. 

rods, 70. 

soluble, 355. 

tubes, to bend, 17. 
to cut, 17. 
to draw out, 109. 
Globulin, 546. 
Globulins, 549. 
Glonoine, 458. 
Glucinum, 725. 
Glucose, 467. 
Glucoses, 467. 
Glucosides, 499. 
Glucusimide, 445. 



Glue, 549. 
Gluside, 445. 
Glusidum, 445. 
Glutanic acid, 497. 
Gluten and Glutin, 473. 
Glyceric acid, 490. 

hydrate, 436. 
Glycerin, 213, 436, 457. 

test for, 457. 
Glycerinum, 457. 

impurities in, 713. 

acidi carbolici, 453, 458. 
gallici, 458. 
tannici, 357, 458. 

aluminis, 458. 

amyli, 458. 

boracis, 333, 458. 
Glyceritum boroglycerini, 334. 

plumbia subacetatis, 212. 
Glycerols, 457. 
Glycyl, 457. 
Glyceryl, 457. 

borate, 335. 

caproate, 462. 

caprylate, 462. 

hydrate, 459. 

laurate, 462. 

margarate, 462. 

myristate, 462. 

oleate, 459. 

palmitate, 462. 

ricinoleate, 464. 

rutate, 462. 

tristearate, 459. 
Glycocholates, 552. 
Glycocine, 552. 
Glycocoll, 552. 
Glvcogen, 476. 
Glycol, 409, 456. 

trichlorethylidene, 486. 
Glycols, 409, 456. 
Glycols, aromatic, 456. 
Glycol lie acid, 409, 489. 

aldehyde, 409. 
Glycyrrhetin, 504. 
Glycyrrhizse radix, 471, 504. 
Glycyrrhizic acid, 504. 
Glycyrrhizin, 504. 
Glycyrrhisinum ammoniatum, 504. 

impurities in, 713. 
Glyoxal, 409. 
Glyoxylic acid, 490. 
series, 490. 
Gnoscopine, 518. 
Goa powder, 338. 
Gold, 245. 

analytical reactions of, 246. 

and sodium chloride, 246. 

coin, 245. 



754 



INDEX. 



Gold, derivation of word, 34. 

earth, 553. 

fine, 245. 

jewellers', 245. 

leaf, 245. 

ochre, 553. 

perchloride, 246. 

sulphide, 246. 

yellow, 553. 
Golden seal, 533. 

syrup, 471. 
Gossypium purificatum, 479. 
impurities in, 713. 
Gothite, 153. 
Goulard's cerate, 212. 

extract, 212. 

water, 212. 
Gracillaria, 479. 
Graham's dialytic process, 704. 

law of diffusion, 24, 58. 
Grain, 608. 

Grains of paradise, 418. 
Gramme, 603. 

relation of, to grains, 610. 
Granati cortex, 359. 

radicis cortex, 359. 
Granatum, 359. 
Granite, 138. 
Granulated phosphorus, 328. 

sulphate of iron, 144. 

tin, 242. 

zinc, 20. 
Gran u lose, 473. 
Grape-sugar, 318, 467. 
Grapes, dried, 318. 

sugar in, 467. 
Graphic formulas, 138, 389, 392, 397. 
Graphite, 30. 
Grass oils, 417, 418, 420. 
Gravel, 579. 
Gravimetric quantitative analysis, 

659. 
Gravitation, 600. 
Gravity, 600. 
Gray powder, 195. 
Green chloride of iron, 149. 

Chinese, 556. 

copperas, 144. 

emerald, 556. 

iodide of iron, 147. 
mercury, 197. 

pigments, 556. 

sulphate of iron, 144. 

ultramarine, 556. 

vitriol, 144. 
Greengage essence, 407. 
Griffith's mixture, 146. 
Grindelia robusta, 537. 
Grindeline, 537. 



Ground-nut oil, 464. 
Group tests, 258. 
Guaiaci lignum, 504. 

resini, 504. 
Guaiaci n, 504. 
Guaiacol, 453. 
Guaiaconic acid, 504. 
Guaiacum, resin of, 504. 
Guaiaretic acid, 504. 
Guaiaretin, 504. 
Guaiaretinic acid, 504. 
Guanine, 515. 
Guano, 362. 
Guarana, 542. 
Guaranine, 542. 
Guaza, 424. 

Guilandina bonducella, 509. 
Guinea grains, 418. 
Gulancha, 509. 
Gum, 116, 478. 

acacia, 116, 478. 

Arabic, 116, 478. 

benjamin, 335. 

British, 477. 

cherry-tree, 479. 

resins, 422, 427. 

tragacanth, 116, 479. 
Gummate of calcium, 116. 

lead, 116. * 
Gummic acid, 479. 
Gunj, 504. 
Gunjah, 423. 
Gun-cotton, 479. 

metal, 241. 
Gunpowder, 291. 
Gurjun balsam, 426. 
Gutta percha, 420. 
Guttse, 608. 

Gynocardia odorata, 509. 
Gypsum, 106, 116. 

Hamamelidis cortex, 509. 

folia, 509. 
Hsematein, 555. 
Hsematin, 546. 
Haematite, brown, 142, 153. 

red, 142, 153. 
Hematoxylin, 555. 
Hsematoxylon, 359, 555. 
Half-sovereign, weight of the, 246. 
Haloid salts, 287. 
Hamamelis virginiana, 509. 
Hambro' blue, 555. 
Hard soap, 461. 
Hardness of water, 315. 
Hashish, 424. 
Heat, latent, 86, 129. 

related to chemical action, 622. 

source of, 17. 



INDEX. 



755 



Heat, specific, 130. 
Heavy carbonate of magnesium, 
119. 

magnesia, 122. 

spar, 103. 

white, 103. 
Heberden's ink, 162. 
Hectare, 604. 
Hedeoma pulegioides, 418. 
Hedeomol, 418. 
Helenin, 418. 
Heliotrope, 507. 
Hellebore, black, 505. 

green, 505, 539. 

white, 539. 

American, 539. 
Helleborein, 505. 
Helleborin, 505. 
Helleborus niger, 505. 

viridis, 505. 
Hemialbumose, 551. 
Hemidesmi radix, 340. 
Hemidesmic acid, 340. 
Hemlock, 417. 
Hemp, Canadian, 509. 

Indian, 423. 
Hempseed calculi, 589. 
Henbane, 538. 

Henry and Dalton's laws, 86. 
Heptane, 398. 
Heptoic aldehyde, 417. 
Heptylene, 408. 
Heptylic acid, 490. 
Herapathite, 524. 
Hesperidene, 416. 
Hesperidin, 509. 

Hevea (Siphonia) Brasiliensis, 420. 
Hexabasic acids, 498. 
Hexabromobenzene, 430. 
Hexachlorobenzene, 430. 
Hexads, 124. 

Hexahydric alcohols, 465. 
Hexahydropyridine, 541. 
Hexahydrodipyridyl, 539. 
Hexane, 398. 
Hexylene, 408. 
Hexylic acid, 490. 
Hibisci capsidse, 479. 
Hibiscus escidentus, 479. 
Hippuric acid, 340, 580. 
Hips, 469. 
Hoffner's blue, 556. 
Holl way's smelting process, 196. 
Homatropinx hydrochloras, 531. 

hydrobromas, 531. 
Homatropine, 531. 
Homochelidine, 541. 
Homologous series, 394. 
Homology, 394. 



Homopterocarpin, 555. 
Homoquinine, 527. 
Homotartaric acid, 497. 
Honey, 469. 
Honeydew, 471. 
Hop, 427, 515, 539. 

essential oil of, 427. 
Hordeum decorticatum, 473. 

starch of (fig.), 475. 
Horehound, 510. 
Horse-chestnut, 537. 
Horseradish oil, 415. 
Huile de Cade, 427. 
Humulus, 427. . 

lupulus, 427, 539. 
Hydrargyri chloridum corrosivum, 
201. 

impurities in, 713. 
mite, 203. 

impurities in, 713. 
cyanidum, 280. 

impurities in, 713. 
iodidum flavum, 197. 

impurities in, 713. 
rubrum, 199. 

impurities in, 713. 
nitratis acidus, liquor, 200. 
oxidum flavum, 204. 

impurities in, 713. 
rubrum, 204. 

impurities in, 713. 
perchloridum, 202. 
subchloridum, 203. 
subsulphas flavus, 228. 

impurities in, 714. 
sidpliuretum cum sulphur e, 208. 
Hydrargyrum, 33, 195. 
impurities in, 714. 
ammoniatum, 206. 

impurities in, 714. 
cum creta, 195. 

impurities in, 714. 
Hydrastine, 535. 
Hydrastininx hydrochloras, 538. 

impurities in, 714. 
Hydrastinine, 538. 
Hydrastis canadensis, 533. 

rhizoma, 533. 
Hydrate of aluminium, 140. 
ammonium, 92. 
barium, 103. 
benzoyl, 493, 534. 
bismuth, 254. 
bromal, 488. 
butyl chloral, 488. 
cadmium, 250. 
calcium, 107. 
cetyl, 450. 
chloral, 486. 



756 



INDEX. 



Hydrate of chromium, 240. 

cobalt, 235. 

copper, 193, 194. 

lime, 107. 

manganese, 234. 

nickel, 237. 

potassium, 62. 

sodium, 82. 

zinc, 136. 
Hydrated oxide of iron, 151, 152. 

substances, 85. 
Hydrates, composition of, 66. 

identified, 377. 

of the hydrocarbons, 436. 
Hydraulic cement, 355. 
Hydrazine, 515. 
Hydrazobenzene, 430. 
Hydric acetate, chloride, nitrate, 
sulphate, etc. See the re- 
spective acids, Acetic, Hy- 
drochloric, etc. 
Hydride of antimony, 185. 

arsenum, 174. 

benzoyl, 492. 

copper, 345. 

ethyl, 397. 

methyl, 396. 

phosphorus, 343. 

silicon, 355. 
Hydrides, 124. 
Hydriodic acid, 272. 

volumetric estimation of, 
644. 
Hydrium, 21. 
Hydrobromic acid, 269. 

ether, 402. 
Hydrocarbons, 391. 

acetylene series, 411. 

anthracene series, 434. 

basylous, 391. 

benzene series, 429. 

dihydroxyl derivatives, 456. 

monohydroxyl derivatives, 436. 

naphthalene series, 433. 

neutral, 391. 

normal, 391. 

olefin e series, 408. 

paraffin series, 396. 

polyhydroxyl derivatives, 465. 

saturated, 392. 

series of, 394. 

terpene series, 412. 

trihydroxyl derivatives. 457.. 

unsaturated, 393. 
Hydrochlorate of apomorphine, 519. 

morphine, 516. 

quinine, 522. 
Hydrochloric acid, 30, 265. 

analytical reactions of, 268. 



Hydrochloric acid, antidote to, 268. 
common, 266. 
dilute, 265. 

in organic mixtures, de- 
tection of, 564. 
volumetric estimation of, 
637. 
Hydrochlorides, 266. 
Hydrocotarnine, 518. 
Hydrocoto'in, 502. 
Hydrocotyle asiatica, 509. 
Hydrocyanic acid, 279. 

analytical reactions of, 283. 
antidotes to, 283. 
diluted, 281. 
from bitter almond and 

cherry-laurel, 500. 
inhalation of, 282. 
in organic mixtures, de- 
tection of, 565. 
in the blood, 284. 
Schonbein's test for, 284. 
volumetric estimation of, 
640. 
Hydroferricyanic acid, 341. 
Hydroferrocyanic acid, 340. 
Hydrofluoric acid, 342. 
Hydrogen, 21. 

antimoniuretted, 185. 
arseniuretted, 174. 
benzoate, borate, etc. Vide the 
respective acids, Benzoic, 
Boracic, etc. 
combustion of, 22. 
dioxide, 103. 

volumetric estimation of, 
653. 
derivation of word, 32. 
explosion of, 22. 
functions of, 124. 
heavy carburetted, 408. 
in artificial light-producers, 22. 
light carburetted, 396. 
lightness of, 22. 
peroxide, 103. 
persulphide, 303. 
phosphoretted, 343. 
preparation of, 21. 
properties of, 21, 24. 
quantitative estimation of, in 
organic compounds, 638, et 
seq. 
salts of, 263. 
siliciuretted, 355. 
sulphuretted, 97, 301, 303. 
type, 379. 

used for balloons, 24. 
weight compared with air, 24. 
weight of 1 litre, 621. 



INDEX. 



757 



Hydrogen, weight of 100 cubic 

inches, 621. 
Hydrogenium, 21. 
Hydrolysis, 460. 
v Hydrolysts, 441. 
Hydrometers, 616. 
Hydroquinine, 527. 
Hydroquinone, 455, 501, 521. 
Hydrosulphuric acid, 301. 
Hydrosulphurous acid, 346. 
Hydrosulphyl, 303. 
Hydrous butyl chloral, 488. 

compounds, 85, 121. 

ferric chloride, 150. 
Hydroxy acetic acid, 409, 492. 
Hydroxybenzoic acid, 493. 

aldebyde, 493. 
Hydroxybenzylic alcohol, 456. 
Hydroxybutyric acid, 490. 
Hydroxycaproic acid, 490. 
Hydroxydodecylic acid, 490. 
Hydroxy formic acid, 489, 490. 
Hydroxyheptilic acid, 490. 
Hydroxyl, 66, 303. 
Hydroxylamine, 516. 
Hydroxyoctilic acid, 490. 
Hydroxypentilic acid, 490. 
Hydroxy - propane - tricarboxylic 

acid, 498. 
Hydroxypropionic acid, 490. 
Hydroxysuccinic acid, 496. 
Hydroxytoluic acid, 493. 
Hygiene, 15. 

Hyoscinse hydrobromas, 538. 
impurities in, 714. 
Hyoscine, 538. 
Hyoscyamia, 538. 
Hyoscyaminse hydrobromas, 538. 

impurities in, 714. 
Hyoscyamine, 538. 
Hyoscyamus, 538. 
Hyper-, meaning of, 149. 
Hypnone, 498. 
Hypo-, meaning of, 344. 
Hypobromites, 271. 
Hypochloride of sulphur, 304. 
Hypochlorite of calcium, 114. 

sodium, 88. 
Hypochlorites, 292. 
Hypochlorous acid, 292. 
Hypogsein, 464. 
Hypopbosphite of calcium, 343. 

sodium, 344. 
Hypophosphites, 344. 
Hypophosphoric acid, 353. 
Hypophosphorous acid, 344. 

estimation of, 638, 654. 
Hyposulphite of calcium, 303. 

sodium, 345. 
33 



Hyposulphite of sodium, standard 

solution of, 655. 
Hyposulphites, 345. 
Hyposulphurous acid, 345. 

-ic, meaning of, 73, 143. 

Icacin, 426. 

Iceland moss, 338, 476. 

Ichthyocolla, 549. 

-ide, meaning of, 76. 

Igasurine, 528. 

Ignition, 102. 

Illicium, 415. 

Illicium anisatum, 415. 

Illuminating agents, analysis of, 706. 

Imidazoic acid, 515. 

Imidogen bases, 431. 

Incense, 428. 

Inch, 608. 

Incineration, 102. 

of filters in quantitative anal- 
ysis, 659. 
Indelible ink, 218. 
Indestructibility of force, 38. 

of matter, 13, 38. 
Indian, barberry, 533. 

gamboge, 427. 

hemp, 423. 

ink, 556. 

ipecacuanha, 537. 

liquorice, 504. 

melissa oil, 420. 

mustard, 451. 

pennywort, 509. 

red, 555. 

yellow, 553. 
India-rubber, 420. 

vulcanized, 420. 
Indican, 291. 
Indicator, 626. 
lndiglucin, 291. 
Indigo, 291. 

blue, 291. 

sulphate of, 291. 

white, 291. 

wild, 532. 
Indigos;en, 291. 
Indigotin, 291. 

disulphonic acid, 291. 
Indium, 725. 

Infusible white precipitate, 207. 
Infusions, 589. 

Infusum dnchonse addum, 522. 
Inhalation of chlorine, 29. 

conine, 536. 

hydrocyanic acid, 282. 
Inhalations, 589. 

Injectio apomorphinx hypodermica, 
520. 



758 



INDEX. 



Injectio morpldnse hypodermica, 517. 
Ink, black, 162, 358, 556. 

Heberden's, 162. 

indelible, 218. 

Indian, 556. 

invisible, 236. 

marking, 218. 

printer's, 556. 

sympathetic, 236. 
Inorganic chemistry, 383. 

compounds, 383. 
Inosite, 469. 
Insecticide, 425. 
Introduction, 13. 
Inula, 418. 

Inula Helenium, 418, 476. 
Inulic anhydride, 418. 
Inulin, 476. 
Inulol, 418. 
Inverted sugar, 468. 
Invisible ink, 236. 
Iodal, 488. 

lodate of potassium, 75, 396. 
Iodates, 396. 
Iodic acid, 396. 
Iodide of ammonium, 274. 

antimony, 180. 

arsenum, 168. 

bismuth and potassium, 571. 

cadmium, 250. 

copper, 276. 

ethyl, 402. 

hydrogen, 273. 

iron, 31, 147. 

lead, 213. 

potassium, 75, 274. 

detection of iodate in, 76. 

silver, 220, 275. 

starch, 275, 473. 

sulphur, 274. 
Iodides, 272. 

analytical reactions of, 275. 

of mercury, 197. 

quantitative estimation of, 677. 

separation of, from bromides 
and chlorides, 276. 
Iodine, 30, 272. 

its analogy to chlorine and bro- 
mine, 272, 278. 

chloride, 273. 

derivation of word, 32. 

moisture in, 678. 

molecular weight of, 198, 273. 

solution of, 274. 

standard solution of, 645. 

tincture of, 274. 

volumetric estimation of, 656. 

water, 274. 
Iodoformum, 401, 444. 



Iodoformum, impurities in, 714. 
Iodo-salicylic acid, 493. 
Iodol, 513. 
Iodopyrrol, 513. 
lodum, 212.- 

impurities in, 714. 
Ipecacuanha, 537. 
Ipomoea orizabensis, 505. 
purga, 505. 
simulans, 505. 
turpethum, 201. 
Iridin, 509. 
Iridium, 247, 725. 
chloride, 571. 
Iris florentina, 418. 
versicolor, 509. 
Irish moss, 479. 
Irisin, 509. 
Iron, 142. 

acetate, 153, 300. 
acetonitrate, 158. 
alum, 139. 

ammonio-citrate, 154. 
ammonio -tartrate, 154. 
analytical reactions of, 160. 
arsenate, 146, 170, 179. 
bromide, 148. 
carbonate, 145. 

saccharated, 145. 
volumetric estimation of, 
650. 
cast, 142. 

chloride, green, 149. 
citrate, 157. 

and quinine, 155, 523. 
compounds, nomenclature of, 

143. 
derivation of word, 32. 
detection of, in presence of 

aluminium and zinc, 163. 
dialyzed, 160. 
ferrocyanide of, 341. 
galvanized, 131. 
hydrate, 151. 
hydrated oxide, 151. 
iodate, 396. 
iodide, 31, 147. 
magnetic oxide of, 142. 

estimation of iron in, 
651. 
meconate, 349. 
nitrate (pernitrate) of, 157. 
in compounds, estimation of, 

669. 
ore, magnetic, 142. 
needle, 153. 
spathic, 142. 
specular, 142. 
oxide, 152, 153. 



INDEX. 



759 



Iron oxyhydrate, 153. 

oxysuiphate, 145. 

perchloride, anhydrous, 148. 

perhydrate, 151. 

pernitrate, 157. 

peroxide, 152. 

separation of, from phos- 
phates and oxalates, 375. 

peroxhydrate, 151. 

persulphate, 150. 

phosphate, 146, 161, 331. 

volumetric estimation of, 
651. 

potassio-citrate, 154. 

potassio-tartrate, 154. 

pyrites, 142. 

quantitative estimation of, 669. 

red oxide of, 153. 

reduced, 158. 

rust of, 143. 

saccharated carbonate of, 145. 
volumetric estimation 
of, 650. 

salts, nomenclature of, 143. 

scale, compounds of, 154. 

separation of, from aluminium 
and chromium, 240. 

sodio-citrate, 157. 

sodio-tartrate, 157. 

sulphate, 144. 

sulphide, 31, 147, 161, 162. 

sulphocyanate, 162, 356. 

tartrate, 156. 

wine of, 157. 

wrought, 142. 
Ironstone, clay, 142. 

chrome, 238. 
Isaconitine, 530. 
Isatropyl-ecgonine, 534. 
Isinglass, 504. 
Iso-, meaning of, 55, 480. 
Isoamylic hydride, 398. 
Isobutane, 398. 
Isoheptoic acid, 418. 
Isomeric bodies, 480. 
Isomerides, 480. 

physical, 482. 
Isomerism, 480. 
Isomers, 480. 

Isomorphism, the doctrine of, 55. 
Isomorphous bodies, 55. 
Isonandra gutta, 420. 
Isonitriles, 483. 
Isophthalic acid, 497. 
Isoprophylactic acid, 488. 
Isorottlerin, 425. 
Ispaghul, 479. 
-ite, meaning of, 73. 
Ivory-black, 556. 



Jaboeandi, 540. 
Jaboridine, 541. 
Jaborine, 540. 
Jalap, Mexican male, 505. 

resin, 505. 

Tampico, 505. 

true, 505. 
Jalapa, 505. 

impurities in, 714. 
Jalapic acid, 505. 
Jalapin, 505. 
Jalapinol, 505. 
" James's powder," 184. 
Japaconitine, 530. 
Jamie brillant, 250. 
Jelly, vegetable, 479. 
Jequeritin, 504. 
Jequerity, 504. 
Jequerity- zymase, 504. 
Jervine, 539. 
Juglandine, 539. 
Juices, 589. 
Juniper oil, 418. 
Juniper-tar oil, 427. 
j Juniperus oxycedrus, 427. 
Juniper us sabina, 419. 

Kainite, 61. 
Kairine, 514. 526. 
Kairoline, 526. 
Kaladana resin, 505. 
Kali, 32, 88. 
Kalium, 32. 
Kamala, 425. 
Kaolin, 355. 
Kariyat, 509. 
Kelp, 272. 

Kermes, mineral, 184. 
Ketone-chloroform, 402. 
Ketones, 498. 
Ketose, 467. 
Kieselguhr, 548. 
Kieserite, 118. 
Kilbride, mineral, 153. 
Kiln, 107. 
Kilogramme, 604. 
Kilolitre, 604. 
Kilometre, 604. 
Kinates. See Quinates. 
Kinetic theory, 24. 
King's blue, 555. 
Kino, 359. 

Kinone. See Quinone. 
Kiwach, 242. 
Kjeldahl's process, 692. 
Kokum butter, 462. 
Kola-nut, 543. 
Kosin, 424. 
Koussin, 424. 



760 



INDEX. 



Kousso, 424. 
Kramerise radix, 359. 
Kunch, 504. 

" Labbaraque's Solution," 88. 
Laboratory furniture, xiii. 
Laburnum, 536. 
Lac, 546. 
Lac, 555. 

dye, 555. 

seed, 555. 

shell, 555. 

stick, 555. 
Lactams, 507. 
Lactates, 347. 
Lactic acid, 347, 489, 490. 

volumetric estimation of, 
637. 

series of acids, 489. 

relations to acetic and gly- 
oxylic series, 490. 
Lactims, 507. 

Lactoglucose. See Glucose. 
Lactometer, 547. 
Lactone, 507. 
Lactones, 507. 
Lactose, 471. 
Lactuca, 509. 
Lactucarium, 509. 
Lactucin, 509. 
Ladies' slipper, 510. 
Lgevogyrate, 467. 
Lsevoracemic acid, 320. 
Lsevorotation, 467. 
Lsevotartaric acid, 320. 
Lsevulose, 468, 469. 
Lakes, 554. 
Lamellae, atropinse, 531. 

physostigminx, 540. 
Lampblack, 556. 
Lamps, gas-, 17. 
Lana philosophica, 135. 
Lanolin, 460. 
Lanthanum, 726. 
Lanthopine, 518. 
Lapis lazuli, 556. 
Lappa, 509. 
Lappa officinalis, 509. 
Larch-bark, 359. 
Lard, 462. 

benzoated, 462. 

oil, 462. 

prepared, 462. 

purified, 462. 
Laricis cortex, 359. 
Larix europsea, 359. 
Larixin, 360. 
Larixinic acid, 360. 
Latent heat, 86, 129. 



Laudanine, 518. 
Laudanosine, 518. 
Laughing-gas, 95. 
Laurate of glyceryl, 462. 
Laurel camphor, 421. 
Laurie acid, 462, 490. 

aldehyde, 419. 
Laurocerasi folia, 500. 
Lavender oil, 418. 

-water, 415. 
" Law," Avogadro's and Ampere's, 
53. 

Berthollet's, 379. 

Boyle's, 53, 619. 

Charles's, 53, 619. 

Dalton's, 48, 49. 

Dulong and Petit's, 623. 

Gay-Lussac's, 54. 

Graham's, 24, 58. 

Henry and Dalton's, 86. 

Malaguti's, 379. 

Mariotte's, 54, 619. 
Law concerning molecular weight, 
55. 

of constant proportions, 47. 

diffusion, definition of, 58. 

indestructibility of matter, 13. 

multiple proportions, 49, 198. 

solubility of gases in liquids, 
86. 

The Periodic, 380. 
Laws of chemical combination by 
weight, 47, 52, 59, 198, et seq. 

chemical combination by vol- 
ume, 49, 59, et seq. 
Lead, 210. 

acetate, 211. 

estimation of, 631. 

analytical reactions of, 214. 

antidotes to, 215. 

carbonate, 211, 215. 

chloride, 214. 

chromate, 215. 

derivation of word, 33. 

detection of, in organic mix- 
tures, 563. 

gummate of, 116. 

hydrato-carbonate, 210. 

iodide, 213. 

nitrate, 212. 

oleate, 213. 

oxide, 210. 

oxyacetate, 211. 

oxychromate, 215. 

percbloride, 213. 

peroxide, 212. 

plaster, 213. 

puce-colored oxide or peroxide 
of, 212. 



INDEX. 



761 



Lead, pyrophorous, 159. 

quantitative estimation of, 675. 

quantivalence of, 211. 

red, 212. 

shot, 210. 

subacetate, 211. 

sugar of, 211. 

sulphate, 215. 

sulphide, 214. 
native, 210. 

test for, in water, 214. 

tree, 215. 

volumetric estimation of solu- 
tions of acetate of, 631. 

white, 210. 
Leadstone, 142. 
Leaf-green, 556. 
Lecanora, 556. 
Lees, 318. 
Legumin, 548. 
Lemon and kali, 88. 
Lemon-chrome, 215. 

-grass oil, 420. 

-juice, 325. 

estimation of mineral acids 
in, 682. 

oil, 416. 
Length, unit of, 603. 
Lentisk tree, 424. 
Lepidolite, 227. 
Leptandra, 510. 
Leptandrin, 510. 
Leucic acid, 490. 
Leucine, 513. 
Leucomaines, 513. 
Levisticum, 428. 
Levulose, 468. 
Lichen blue, 555. 

sugar, 465. 
Lichenin, 476. 
Lichestearic acid, 338. 
Light magnesium carbonate, 119. 

carburetted hydrogen, 395. 

magnesia, 122. 
Lignin, 479. 
Lime, bisulphite, 306. 

carbonate, 108. 

precipitated, 108. 

caustic, 107. 

chloride of, 114. 

hydrate, 107. 

juice, 325. 

estimation of mineral acids 
in, 682. 

kiln, 107. 

oil, 416. 

phosphate, 113. 

quick, 107. 

slaked, 107. 



Lime, sulphurated, 115. 
Lime-water, 108. 
Limestone, 106. 

magnesian, 118. 
mountain, 118. 
Limonenes, 412. 
Limonis cortex, 416. 
succus, 324. 

impurities in, 714. 
Limonite, 153. 
Linamarin, 500. 
Liniment of mercury, 195. 
Linimentum ammonise, 461. 

calcis, 461. 
Linkage of atoms, 389, 430. 
Linoleine, 463. 
Linoxyn, 463. 
Linseed, 463, 479. 
cake, 463. 
meal, 463. 
oil, 463. 
tea, 479. 
Linum usitatissimum, 479. 

impurities in, 714. 
Liqueurs, 441. 
Liquid, definition of, 58. 

camphor, 421. 
Liquidambar orientate, 495. 
Liquids, specific gravity of, 614. 

official, specific gravity of, 614. 
Liquor acidi arsenosi, 168. 

vol. est. of, 648. 
acidi chromici, 239. 

arsenosi, 168. 
ammonii acetatis, 93. 
impurities in, 714. 
citratis, 95. 
fortior, 95. 
antimonii chloridi, 180. 

estimation of anti- 
mony in, 671. 
arseni et hydrargyri iodidum, 167. 
bismuthi, 254. 

et ammonii citratis, 254. 

estimation of bis- 
muth in, 672. 
calcis, 108. 

impurities in, 714. 
vol. est. of, 635. 
chlorinatse, 115. 
cocainse hydrochloratis, 534. 
ferri acetatis, 150. 

estimation of iron 

in, 669. 
impurities in, 714. 
citratis, 154. 

impurities in, 714. 
chloridi, 150. 

impurities in, 714. 



702 



INDEX. 



Liquor ferri dialysatus, 160, 705. 
est. of iron in, 669. 
nitratis, 158. 

estimation of iron in, 

669. 
impurities in, 714. 
persulphatis, 151. 

estimation of iron in, 

669. 
impurities in, 714. 
subsulphatis, 151. 

impurities in, 714. 
gutta-percha, 421. 
glonoini, 458. 
hydrargyri nitratis, 200. 

impurities in, 714. 
perchloridi, 202. 
iodi composites, 317. 
lithise, effervescens, 228. 
magnesii carbonatis, 120. 

citratis, 122. 
morpMnse acetatis, 517. 
bimeconatis, 518. 
hydrochloratis, 517. 
sulphatis, 518. 
nitroglycerin, 458. 
plumbi subacetatis, 212. 
dilutus, 212. 
impurities in, 714. 
potassse, 63, 67. 

impurities in, 714. 
effervescens, 72. 
neutralizing power of, 68. 
specific gravity of, 614. 
to prepare, 68. 
potassii arsenitis, 168. 
permanganatis, 232. 
soda?, 82. 

impurities in, 714. 
chloratse, 87. 

impurities in, 714. 
effervescens, 86. 
sodii arsenatis, 170. 
ethylatis, 443. 
silicatis, 355. 
strychninse hydrochloratis, 528. 
smci chloridi, 133. 
Liquorice, 471, 504. 
sugar, 471, 504. 
List of apparatus, xii. 

chemical substances, xiv. 
reagents, xiii. 
Litharge, 210. 
Lithates, 362. 
Lithic acid, 362. 
Lithii benzoas, 227. 

impurities in, 714. 
bromidum, 227. 

impurities in, 714. 



Lithii carbonas, 227. 

impurities in, 715. 
citras, 227. 

impurities in, 715. 
salicylas, 227. 

impurities in, 715. 
Lithium, 227. 

analytical reactions of, 228. 
and platinum chloride, 228. 
benzoate, 227. 
bromide, 227. 

volumetric estimation of, 
634. 
carbonate, 227. 

vol. est. of, 634. 
citrate, 227. 

vol. est. of, 634. 
derivation of word, 31. 
flame, 228. 
• fluoride, 227. 
salicylate, 227. 

volumetric estimation of, 
634. 
silicate, 227. 
sulphate, 228. 
urate, 228. 
Litmus, 96, 555. 
paper, 96. 

solution of, 96, 636. 
tincture of, 96. 
Litre, 603. 

relation of, to pints, 604. 
Liver of sulphur, 69. 
Lixiviation, 89. 

fractional, 378. 
Loadstone or lodestone, 142. 
Lobelia, 539. 
Lobelina, 539. 
Lobeline, 539. 
Lodestone, 142. 
Loganetin, 506. 
Loganin, 506. 
Logwood, 359, 555. 

solution of, bleached by chlo- 
rine, 29. 
Lokas, 556. 
Long pepper, 541. 
Looking-glasses, 241. 
Lotio hydrargyri flava, 204. 

nigra, 205. 
Louisa blue, 556. 
Lozenges, 303, 589. 

bicarbonate of sodium, 87. 
bismuth, 252. 

chlorate of potassium, 295. 
morphine, 517. 

and ipecacuanha, 517. 
reduced iron, 158. 
sulphur, 303. 



INDEX. 



763 



Lucifers, 25. 
Lump-sugar, 469. 
Lunar caustic, 218. 
Lupulin, 427. 

oleo-resin of, 427. 
Lupuline, 539. 
Lupulinic acid, 427. 
Lupulinuin, 427. 

impurities in, 715. 
Lupulus, 427, 539. 
Luteolin, 554. 
Lutidine, 513. 
Luting, 98. 

fire-clay, 202. 

linseed meal, 98. 
Lycopodium, 664. 

impurities in, 715. 
Lycopodium clavatum, 664. 

Mace, fixed oil of, 462. 

volatile oil of, 419. 
Macleyine, 541. 
Madder, 434, 554. 
Magenta, 557. 
Magnesia, 122. 

calcined, 122. 

carbonate of, 119, 120. 

effervescing citrate of, 122. 

fluid, 120. 

heavy, 122. 

hydrous carbonate of, 119. 

impurities in, 715. 

light, 122. 

sulphate, 118. 
Magnesia carbonas levis, 129. 

levis, 122. 

ponderosa, 122. 
Magnesian limestone, 108. 
Magnesii carbonas, 119. 

impurities in, 715. 
ponderosa, 119. 

carbonatis, liquor. 120. 

citratis effervescens, 122. 
liquor, 122. 

sulphas, 118. 

impurities in, 715. 
Magnesite, 118. 
Magnesium, 118. 

analytical reactions of, 122. 

and ammonium arsenate, 122. 
phosphate, 122, 330. 
sulphate, 685. 

carbonate, 119. 

chloride, 118. 

citrate, 122. 

derivation of word, 32. 

detection of, in presence of 
barium and calcium, 126. 

euxanthate, 554. 



Magnesium, for analytical purposes, 
174. 

oxide, 122. 

phosphates in bones, 112. 

purrate, 553. 

quantitative estimation of, 666. 

separation from barium and 
calcium, 126. 

silicate, 354. 

sulphas effervescens, 119. 

sulphate, 118. 
Magnetic iron ore, 142. 

vol. est. of, 651. 
Magnolia, 509. 

Magpie test for mercury, 209. 
Maize starch (fig.), 475. 
Malachite, 190. 
Malaguti's law, 379. 
Malate of atropine, 531. 

nicotine, 539. 
Malates, 348. 
Male fern, oil of, 464. 
Malic acid, 348, 496. 

series of acids, 496. 
Mallow tea, 479. 
Malonic acid, 497. 
Malt, 478. 

extract, 478. 

substitutes, 468. 
Maltose, 468, 470, 471. 
Manganate of potassium, 77, 231. 

sodium, 232. 
Manganese, 231. 

analytical reactions of, 233. 

black oxide of, 231. 

Crum's test for, 234. 

derivation of word, 34. 

dioxide, 231. 

quantitative analysis of black 
oxide of, 667. 
Manganesii oxidum nigrum, 231. 
Mangani dioxidum, 231. 

impurities in, 715. 

sulphas, 234. 

impurities in, 715. 
Manganous chloride, 231. 

hydrate, 234. 

sulphide, 233. 
Mangosteen oil, 463. 
Manihot, starch of (fig.), 475. 
Manna, 465. 
Mannite, 465. 

Manufacturing cbemists, 14. 
Manures, analysis of, 706. 
Maranta, starch of (fig.), 475. 
Marascbino, 441. 
Marble, 106. 
Margarine, 462. 
Margosa-bark, 509. 



764 



INDEX. 



Marigold, 509. 

Marine soap, 462. 

Mariotte's law, 53, 619. 

Marking ink, 218. 

Marl, 138. 

Marmor album, 106. 

Marrubium, 510. 

Mai-seilles soap, 461. 

Marsh gas, 396. 

Marsh -gas series, 395. 

Marshmallow, 479. 

Marsh's test for arsenum, 173. 

Massa ferri carbonatis, 145. 
hydrargyri, 195. 

Massicot, 210. 

Mastic, 424. 

Mastiche, 424. 

Mastichic acid, 424. 

Masticin, 426. 

Mate, 542. 

Maticse folia, 510. 

Matico, 510. 

Matricaria, 415 

chamomilla, 415. 

Matter, indestructible, 13, 38. 
origin of, 38. 

Mauve, 501, 757. 

May-apple, 425. 
Mayer's reagent, 630. 
Meadow-sweet. 493, 507. 
oil of, 407, 493, 507. 
Measures, 605, et seq. 
Mechanical and chemical combina- 
tion, 31, 36. 
medicines, 242. 
Meconate of iron, 349. 

morphine, 517. 
Meconic acid, 349, 567. 
Meconidine, 518. 
Meconin, 518. 
Meconoisin, 518. 
Meerschaum, 354. 
Mel, 471. 

impurities in, 715. 
boracis, 333. 
despumatum, 559. 
Melam, 357. 
Melassa, 419. 
Melasses, 471. 
Melegueta pepper, 418. 
Meletizose/471. 
Melia azedarach, 510. 
Melissa oil, 420. 
Melissic acid, 489, 490. 

alcohol, 450. 
Melissvl, palmitate of, 450. 
Melitose, 471. 
Melitic acid, 498. 
Mellon, 357. 



Melon essence, 407. 
Melting-points, table of, 598, 599. 

of fats, etc., 548. 

to determine, 598. 

of metals, 599. 
Memoranda, analytical, 100, 224, 

259, 365. 
Menispermum canadense. 533. 
Mentha arvenis, 419. 

pulegium, 419. 
Menthene, 419. 
Menthol, 419, 452. 

impurities in, 715. 
Mercaptans, 445. 
Mercurialine, 512. 
Mercuric ammonium, chloride of, 
205. 

chloride, 201. 

cyanide, 280. 

hexiodide, 273. 

iodide, 197. 

nitrate, 199. 

oxide, 204. 

oxy nitrates, 200. 

oxysulphate, 201. 

phenylate, 454. 

potassium iodide, volumetric 
solution of, 658. 

salts, 196. 

analytical reactions of, 205. 

sulphate, 200. 

sulphide, 208. 

sulphocyanate, 357. 
Merctirius vitas, 181. 
Mercurous ammonium, chloride of, 
206, 208. 

chloride, 203, 209. 

chromate, 209. 

compounds, 196. 

iodide, 197. 

niti-ate, 199. 

oxide, 205. 

salts, 196. 

analytical reactions of, 205, 
208, 209. 

sulphate, 201. 

sulphide, 208. 
Mercury, 195. 

amido-chloride, 206. 

ammoniated, 206. 

ammonio-chloride, 206. 

analytical reactions of, 205. 

antidotes to, 209. 

basic sulphate, 201. 

bichloride, 201. 

black oxide, 204. 

carbonates, 209. 

chlorides, 201. 

derivation of word, 33. 



INDEX. 



765 



Mercury, detection of, in organic 
mixtures, 562. 

formula of, 195. 

fulminate, 219. 

galvanic test for, 209. 

hexiodide, 273. 

iodides, 197. 

magpie test for, 209. 

molecular weight of, 195. 

native sulphide, 195. 

nitrates, 199. 

nomenclature of salts of, 196. 

of life, 181. 

oleate of, 460. 

oxides, 204. 

oxynitrates, 200. 

oxysulphate, 201. 

oxysulphide, 208. 

perchloride, 201. 

persulphate, 200. 

phenylate, 454. 

quantitative estimation of, 673. 

subchloride, 203, 209. 

sulphates, 200. 

sulphide, 195. 

yellow oxide, 204. 
Mesitylene, 429. 
Mesoxalic acid, 493. 
Meta-, meaning of, 349, 455. 
Metaboric acid, 333. 
Metachloral, 486. 
Metacinnamein, 495. 
Metagummic acid, 479. 
Metaldehyde, 485. 
Metallic elements, 15. 
Metalloids, 16. 
Metals, 16. 

of minor pharmaceutical im- 
portance, 226. 

quantitative estimation of, 659. 

table of the fusibility of, 599. 
Metamerides, 481. 
Metamerism, 481. 
Metamers, 481. 
Metantimonic acid, 181. 
Metaphosphates, 349. 
Metaphosphoric acid, 330, 349. 
Metastannates, 243. 
Metastanuic acid, 243. 
Metastyrol, 495. 
Metathesis, 59, 79, 107. 
Metavauadates, 332. 
Methacrylic acid, 491. - 
Methane, 396. 

series, 395. 

substitution-products of, 399. 
Methoxycatechol, 336. 
Methylal, 486. 
Methylamine, 512. 
33* 



Methylated spirit, 437. 

sweet spirit of nitre, 438. 
Methyl beuzene, 431. 

arbutin, 501. 

carbinol, 439. 

chloride of, 399. 

conine, 536. 

dichlorobenzene, 432. 

ethyl, 397. 

formic acid, 484. 

group, 431. 

hydride of, 396. 

monochlorobenzene, 432. 

morphine, 520. 

nonyl-ketone, 419, 498. 

phenoene, 429, 431. 

prophyl -phenoene, 429, 432. 

protocatechuic aldehyde, 364. 

salicylate, 407, 492. 
impurities in, 715. 

theobromine, 543. 

trichlorobenzene, 432. 
Methyl salicylas, 492. 

impurities in, 715. 
Methylic acid, 490. 

alcohol, 437. 

detected in presence of 
ethylic alcohol, 438. 
Metre, 604. 

relation of, to inches, 604. 
Metric system, 601, et seq. 
Metrical system, weights and meas- 
ures of, 604, et seq. 
Metrical system of weights and 
measures, its relation to the 
British, 608, et seq. 
Meum, 428. 
Mezereum, 425. 
Mica, 138. 
Mica panis, 471. 
Microcosmic salts, 373. 
Microscopic examination of urinary 

sediments, 581. 
Microscopy of starches, 474. 
Micro-spectroscope, 560. 
Milk, 546. 

poison, 513, 571. 

curdling ferment, 546. 

of sulphur, 303. 

sugar, 471. 
Mimetesite, 332. 
Mimotannic acid, 359. 
Mineral acids, detection of, in or- 
ganic mixtures, 564. 
Mineral, chameleon, 232. 

kermes, 182. 

Kilbride, 153. 

purple, 555. 

rouge, 153, 555. 



766 



INDEX. 



Minerals, general analysis of, 370, 
et seq. 

special analysis of, 687. 
Minim, 608. 
Minium, 210. 
Mint, 419. 

Mirbane, essence of, 430. 
Mishmi bitter, 533. 
Mispickel, 168. 
Mistura Jerri aromatica, 162. 

composita, 146. 
Mitigated caustic, 218. 
Mixed ethers, 447. 
Mixture, different from chemical 
combination, 31, 36. 

definition of, 57. 
Mixtures, 589. 
Mohr's burette, 627. 
Moist sugar, 469. 
Molasses, 471. 
Molecular arsenum, 168. 

attraction, 138. 

composition, 386. 

constitution or structure, 130, 
138, 195, 386, 393, 432. 

density of gases and vapors, 53, 
55, 387, 619. 

electricity, etc., 623. 

ferric chloride, 149. 

formulae as indicated by chem- 
ical " periodicity," 380. 

properties, 387, 395. 

isomorphism, 55. 

phosphorus, 328. 

specific heat, 622. 

substitution, 194. 

sulphur, 302. 

theory, vii. 

volume, 55. 

weight, 55, 621. 

weights, 149, 198. 
definition of, 59. 
Molecule, definition of, 57. 
Molecules, 38. 

conception of, 391, 393. 
Molybdates, 332. 
Molybdenum, 331, 726. 

oxide, 331. 

sulphide, 331. 
Molybdic anhydride, 331. 
Monads, 123. 
Monamines, 512. 
Mon-iodoethane, 403. 
Monobasic acids, 264. 
Monobasylous radicals, 264. 
Monobrom-acetanilide, 431. 
Monobrom-camphor, 421. 
Monobrom-ethane, 403. 
Monobromobenzene, 430. 



Monochlorobenzene, 430. 
Monochloromethane, 399. 
Monochloromethylbenzene, 432. 
Monoformin, 451. 
Monohydroxyl derivatives of the 

paraffins, 436. 
Mononitrocellulin, 479. 
Monoxy naphthalenes, 434. 
Morbid urine, 572. 
Mordants, 140. 
Mori suecus, 554. 
Morphina, 516. 
Morphinse acetas, 517. 

impurities in, 715. 

hydrochloras, 517. 

sulphas, 517. 

impurities in, 715. 
Morphine, or Morphia, 516. 

acetate, 517. 

analytical reactions of, 518. 

bimeconate, 517. 

distinction from brucine, 529. 

hydrochlorate, 517. 

in organic mixtures, detection 
of, 567. 

quantitative estimation of, 
698. 

sulphate, 517. 

tartrate, 517. 
Morrhuine, 463. 
Mortar, 355. 
Mosaic gold, 244. 
Moschus, 549. 

moschiferus, 549. 
"Mother-liquor," 109. 
Motion from heat, 86. 
Mottled soap, 461. 
Mountain-blue, 555. 

limestone, 118. 
Mucic acid, 472. 
Mucilage of bael, 479. 

gum acacia, 116. 

linseed, 479. 

marshmallow, 479. 

squill, 479. 

starch, 473. 

tragacanth, 116. 
Mucilago acacise, 116. 

amyli, 473. 

tragacanthse, 116. 
Mucuna pruriens, 242. 
Mucus in urine, 580. 
Mudar tree, 509. 
Mulberry calculus, 588. 

essence, 407. 

juice, 554. 

sugar in, 467. 
Mulder's process for estimating al- 
cohol, 704. 



INDEX. 



767 



Multiple proportions, law of, second 

law of combination, 49, 198. 
Murex, 362. 
Murexid, 362. 
Muscarine, 513. 
Musk, 549. 

artificial, 549. 

deer, 549. 
Mustard, 451. 

artificial oil of, 451. 

essential oil of, 420. 

fixed oil of, 464. 

"plaster," 451. 
Mycoderma aceti, 297. 
Mydriatics (table), 544. 
Mylabris cichorii, 422. 
Myotics (table), 544. 
Myrcia acris, 441. 
Myristate of glyceryl, 462. 
Myristic acid, 462, 490. 
Myristicene, 419. 
Myristicin, 419. 
Myristicol, 419. 
Myristin, 462. 

Myron ate of potassium, 451. 
Myrosin, 451. 
Myroxxjlon Pereirse, 495. 

toluifera, 495. 
Myrrh, 428. 
Myrrha, 428. 
Myrrhic acid, 428. 
Myrtus communis, 419. 
" Mystery gold," 245. 
Mytiloxine, 513. 

Napelline, 530. 
Naphthalene, 434, 514. 

series of hydrocarbons, 433. 
Napthalic acid, 336. 
Naphthols, 434. 
Naphtalinum, 434. 

impurities in, 716. 
Naphthvl alcohols, 434. 
Naphtol, 434. 

impurities in, 716. 
Narceine, 518. 
Narcotina, 518. 
Narcotine, 518. 
Narthex. See Ferula. 
Nascent state, 40. 
Natal aloes, 435. 
Nataloin, 435. 
Natrium, 32. 
Natron, 32, 286. 
Natural philosophy, 43. 
Nectandra Rodisei, 532. 
Nectandrse cortex, 532. 
Nectandrine, 533. 
Needle iron ore, 153. 



Negative pole, 245. 
Neroli oil, 416. 
Nessler's test, 744. 
Neuridine, 513. 
Neurine, 513. 
Neutral chromate, 105. 
hydrocarbons, 391. 
Neutralization, 96. 
Nickel, 236. 

analytical reactions of, 236. 
arseno-sulphide, 236. 
cobalti cyanide, 237. 
cyanide, 237. 
derivation of word, 34. 
hydrate, 237. 

separation of, from cobalt, 237. 
silver, 236. 
sulphide, 236. 
Nicker-nuts, 509. 
Nicotiana tabacum, 539. 
Nicotine, Nicotia, Nicotina, or Nic- 
otylia, 539. 
malate, 539. 
Nilulum album, 135. 
Nim, 509. 
Niobium, 725. 
Nitrate of ammonium, 94, 288. 

argent-ammon-ammonium, 207. 

barium, 102. 

bismuth, 251. 

copper, 192. 

iron, 157. 

lead, 212. 

mercury, 199. 

pilocarpine, 540. 

potassium, 73, 285. 

silver, 216, 217. 

and potassium, 217. 
standard solution of, 639. 
toughened, 218. 
sodium, 81, 285. 
strontium, 229. 
Nitrates, 285. 

analytical reactions of, 289. 
quantitative estimation of, 678, 
et seq. 
Nitre, 285. 

Chili, 286. 
cubic, 286. 
prismatic, 285. 
sweet spirit of, 351, 403, 438. 
Nitric acid, 285, 287. 

anhydrous, 288. 
antidotes to, 292. 
dil., 288. 

in organic mixtures, detec- 
tion of, 564. 
volumetric estimation of, 
638. 



768 



INDEX. 



Nitric anhydride, 288, 290. 

oxide, preparation of, 289. 

peroxide, 289, 290. 
Nitrification, 286. 
Nitrile bases, 431, 510, 515. 
Nitriles, 483. 
Nitrite of aniyl, 351, 407. 

ethyl, 351, 402. 

potassium, 350. 

sodium, 351. 
Nitrites, 350. 

analytical reactions, 350. 

in water, test for, 350. 
Nitrobenzene, 430. 
Nitrobenzol, 430, 500. 

in oil of bitter almonds, test 
for, 500. 
Nitrocellulin, 470. 
Nitroethane, 405. 
Nitrogen, 25, 289. 

derivation of word, 32. 

in the atmosphere, 25. 

oxides, 289, 290. 

peroxide, 289, 290. 

preparation of, 25. 

properties of, 26. 

quantitative estimation of, in 
organic compounds, 691, etseq. 

relative weight of, 27. 
Nitroglycerin, 458. 
Nitrohydrochloric acid, 187, 289. 
Nitromannite, 465. 
Nitrometer, 351, 405. 
Nitropentane, 408. 
Nitrosulphonic acid, 308. 
Nitrosyl-sulphonic acid, 309. 
Nitrous acid, 289, 290, 350. 

anhydride, 289, 290. 

ether, 403. 

oxide, 95. 
Nomenclature of alkaloids, 515. 

anhydrides, 85. 

anhydrous bodies, 85. 

-ate, 73, 76. 

carbonization, evaporation, ig- 
nition, incineration, 102. 

double salts, 79. 

glucosides, 499. 

hydrates, 66. 

hydric, -ous, 76. 

hydrous bodies, 85. 

-ide, -ite, 76. 

iron salts, 143. 

mercury compounds, 196. 

notes on, 66, 73, 76, 79, 85, 102, 
143, 196, 515. 
Nonane, 398. 
Non-drying oils, 463. 
Non-metallic elements, 15. 



Non-metals, 16. 
Nonylic acid, 490. 
Nordhausen sulphuric acid, 310. 
Normal hydrocarbons, 391. 

solutions, 626. 
Notation, 41. 

of organic compounds, 389, 396. 
Notes, analytical, 224, 259. 
Nutmeg, expressed oil of, 462. 

oil of, 419. 
Nutrition, plastic elements of, 549. 
Nux vomica, 527. 

assay of, 700. 

Oatmeal, 473. 
Occlusion, 248, 249. 
Ochre, 553. 
Octahedron, 172. 
Octylic acid, 490. 
CEnanthylate of ethyl, 407. 
Q^nanthvlic acid, 490. 
Official formula, 28. 

liquids, specific gravity of, 614. 

substances, volumetric estima- 
tion of, 627, et seq. 
Oil of ajowan, 415. 

ajwain, 415. 

almond, 463. 

amber, 356. 

American pennyroyal, 418. 

aniseed, 415. 

apple, 407. 

arachis, 464. 

benne, 464. 

bergamot, 416. 

birch, 407. 

bitter almond, 491, 500. 
artificial, 430, 500. 

"boiled," 463. 

boldo, 416. 

buchu, 416. 

cacao, 462. 

cake, 463. 

cajuput, 416. 

camphor, 421. 

cannabis indica, 423. 

capsicum, 421. 

caraway, 416. 

cardamoms, 416. 

cascarilla, 417. 

cassia, 417. 

castor, 463. 

cedra, 416. 

chamomile, 415. 

cinnamon, 417. 

citron, 416. 

citronella, 417. 

cloves, 416. 

cocoa-nut, 462. 



INDEX. 



769 



Oil, cod-liver, 463. 
copaiva, 417. 
coriander, 417. 
cowbane, 417. 
croton, 463. 
cubeb, 417. 
cummin, 417. 
dill, 415. 
earth-nut, 464. 
eggs, 545. 
elder-flower, 419. 
eucalyptus, 412, 417. 
fennel, 418. 
fir wool, 413. 
garcinia, 462. 
garlic, 452. 
geranium, 418. 
gingelly, 464. 
ginger, 420. 
ginger-grass, 418. 
grains of paradise, 418. 
grass, 417. 
ground-nut, 464. 
hop, 427. 
horseradish, 415. 
Indiau hemp, 423. 
jaborandi, 540. 
juniper, 418. 
lard, 462. 
lavender, 418. 

foreign, 418. 
lemon, 416. 
lemon-grass, 420. 
lime, 416. 
linseed, 463. 
lycopodium, 464. 
mace, fixed, 462. 

volatile, 419. 
male fern, 464. 
mangosteen, 462. 
meadow-sweet, 407, 493, 50" 
melissa, 420. 
mustard, artificial, 451. 

essential, 420, 451. 
fixed, 464. 
myrtle, 419. 
neroli, 416. 
nutmeg, fixed, 462. 

volatile, 419. 
of vitriol, 309. 
olibanum, 428. 
olive, 459, 464. 
omum, 415. ' 
orange-flower, 416. 
orange-rind, 416. 
orris, 418. 
palm, 462. 
paraffin, 398. 
pennyroyal, 419. 



Oil, pepper, 541. 

peppermint, 418. 

petit-grain, 416. 

phellandrium, 412. 

phosphorated, 328. 

pilocarpus, 540. 

pimento, 416. 

pine wool, 413. 

ptychotis, 415. 

resin, 423. 

rose, 419. 

rosemary, 419. 

rue, 419, 498. 

saffron, 554. 

sage, 419. 

sandal-wood, 419. 

sassafras, 420. . 

savin, 419. 

sesame, 464. 

shark-liver, 465. 

spearmint, 419. 

sperm, 450. 

spike, 418. 

star-anise, 415. 

sweet-birch, 407. 

sweet-flag, 420. 

teal, 464. 

tbeobroma, 462. 

thyme, 420. 

turmeric, 420. 

turpentine, 412. 

valerian, 420. 

verbena, 420. 

water-hemlock, 417. 

wine, 409. 

winter-green, 407. 

wood, 426. 
Oils, analysis of, 706. 

and fats, composition of, 459. 

drying, 463. 

essential, 413. 

tested for alcohol, 414. 

fixed, 463. 

non-drying, 463. 

volatile, 413, et seq. 

process for, 414. 
Ointments, 589. 
Okra, 479. 
01, meaning of, 457. 
Oleate of glyceryl, 459. 

lead, 213. 

mercury, 460. 

potassium, 459. 

veratrine, 460. 

zinc, 460. 
Oleates, 459. 
Oleatum hydrargyri, 460. 

veratrinx, 460. 

sinci, 136. 



770 



INDEX. 



Olefiant gas, 408. 

define series of hydrocarbons, 408. 

Olefines, relation to parafiins and 

acetylenes, 410. 
Oleic acid/ 459, 491. 
Oleine, 459. 
Oleo-resina cubebse, 426. 
Oleo-resins, 422, 425. 
Oleum amygdalse, 463. 
amara, 415. 

andropogi citratis, 420. 

anethi, 415. 

anisi, 415. 

anthemidis, 415. 

arachis, 464. 

aurantii corticis, 416. 
florum, 416. 

bergamottse, 416. 

betulse volatile, 407. 

cadinum, 427. 

cajaputi, 416. 

cari, 416. 

carui, 416. 

caryophylli, 416. 

chenopodii, 421. 

cinnamomi, 417. 

copaibse, 417. 

coriandrum, 417. 

crotonis, 463. 

cubebse, All. 

erigerontis, 417. 

eucalypti, 417. 

fozniculi, 418. 

jtmiperi, 418. 

lavandulse, 418. 
florum, 418. 

limonis, 416. 

Zim, 463. 

macis, 419. 

menihse piperitse, 418. 
viridis, 419. 

morrhuse, 464. 

myrcia, 418. 

myristicae, 419. 

expressum, 462. 

myrti, 419. 

oZw«, 459, 464. 

phosplwratum, 328. 

picis liquidzs, 426. 

pimentse, 416. 

j>mi sylvestris, 413. 

ricini, 464. 

rosa?, 419. 

rosmarini, 419. 

rwfce, 419, 498. 

sabinse, 419. 
. santali, 419. 

sassafras, 420. 

sinapis volatile, 419. 



Oleum succini, 356. 

terebinthinse, 412, 413. 

theobromatis, 462. 

thymi, 420. 
Olibanum, 428. 
Olive oil, 459, 464. 
Omentum, 462. 
Omum oil, 415. 
Opal, 354. 
Ophelia chirata, 351. 
Ophelic acid, 351. 
Opianic acid, 518. 
Opianine, 518. 
Opu pulvis, 516. 
Opium, 516. 

alkaloids, 516. 

deodoratum, 516. 

detection of, in organic mix- 
tures, 567. 

estimation of morphine in, 619. 

impurities in, 716. 
Orange chrome, 215. 
Orange-flower oil, 416. 

water, 416. 
Orange-rind oil, 416. 

wine, 441. 
Orchil, 555. 
Orchis tuber, 479. 
Orcin, 456. 
Ordeal-poison, 540. 
Orellin, 554. 
Organic analysis, 557. 
Organic bases, 510. 

chemistry, 383. 

Advice to Students, 381. 

compounds, composition of, 384. 

constitution of, 387. 

notation of, 389, 396. 

radicals, 392. 
Orpiment, 168, 553. 
Orris, butter of, 418. 

camphor of, 418. 

oil of, 418. 
Ortho-, meaning of, etc., 350. 
Orthodihydroxyl benzene, 455. 
Orthohydroxybenzoic aldehyde, 

494. 
Orthophenolsulphonic acid, 454. 
Orthophosphates, 332, 350. 
Orthophosphoric acid, 350. 
Ortho vanadates, 332. 
Oryza, 473. 

sativa, 472, 473. 

starch of (fig.), 475. 
Orysee farina, 473. 
Os ustum, 111. 
Osmium, 726. 
Otto of rose, 419. 
Ouabain, 506. 



INDEX. 



771 



Ounce, 608. 

Ourari, 528. 

-ous, meaning of, 76, 143. 

Ovi albumen, 544. 

Ox-bile, 552. 

Ox-gall, 552. 

Oxalate of ammonium, 95. 

barium, 105, 317. 

calcium, 117, 316. 

cerium, 230. 

silver, 317. 

sodium, 316. 

strontium, 230. 
Oxalates, 316. 

analytical reactions of, 316. 

from phosphates and ferric 
oxide, separation of, 375. 

quantitative estimation of, 684. 
Oxalic acid, 316, 410, 496. 
antidotes to, 317. 
chemically pure, 316. 
in organic mixtures, detec- 
tion of, 564. 
standard solution of, 634. 
Oxamide, 496. 
Oxide of aluminium, 140. 

antimony, 181. 

barium, 103. 

bismuth, 253. 

cadmium, 251. 

calcium, 107. 

chromium, 239. 

cobalt, 235, 555. 

copper, 92. 

iron, 153. 

black, 142. 
magnetic, 142. 

lead, 210. 

magnesium, 122. 

manganese, 231. 

mercury, 204. 

molybdenum, 331. 

silicon, 354. 

silver, 218. 

tin, 243. 

zinc, 135. 
Oxides of nitrogen, 290. 

identified, 377. 
Oxidizing flame, 135. 
Oxyacanthine, 533. 
Oxvacetate of copper, 192. 

lead, 211. 
Oxyacid salts, 287. 
Oxyacids of sulphur, 346. 
Oxycarbonate of bismuth, 253. 
Oxychloride of antimony, 181, 184. 
Oxychromate of lead, 215. 
Oxydizing flame, 135. 
Oxygen, 16. 



Oxygen, analogies of, 173. 

derivation of word, 32. 

from ozone and antozone, 275. 

in the air, 16, 25. 

its relation to animal and 
vegetable life, 19. 

preparation of, 16, 103. 

properties of, 19. 

quantitative estimation, of, in 
organic compounds, 688, et 
seq. 

solubility in water, 19. 

specific gravity of, 24. 

weight of 100 cubic inches, 621. 
Oxygenated water, 103. 
Oxyhydrates of iron, 152. 
Oxyiodide of iron, 147. 
Oxymalonic acid, 497. 
Oxymel, 470. 

of squill, 470. 
Oxymel scillse, 470. 
Oxynitrates of bismuth, 252. 

mercury, 200. 
Oxysalts, 287. 
Oxysuccinic acid, 497. 
Oxy sulphate of iron, 145. 

mercury, 201. 
Oxysulphide of antimony, 182. 

mercury, 208. 
Ozokerite, 450. 
Ozone, 275. 

Palas tree, 359. 
Palladium, 726. 

chloride, 571. 
Palm oil, 462. 
Palmitate of cetyl, 450. 

glyceryl, 462. 

melissyl, 450. 
Palmitic acid, 462, 490. 
Palmitine, 462. 
Pancreatin, 551. 
Pancreatinum, 552. 
Papain, 551. 
Papaver rhceas, 555. 

somniferum, 516. 
Papaverine, 518. 
Papaveris capsulae, 516. 
Papaw, 551. 
Paper, bibulous, 109. 

filtering, 109. 

litmus-, blue, 96. 
red, 96. 

turmeric, 96. 
Papers, test-, 96. 
Para-, meaning of, etc., 320, 455. 
Para-acetphenetidin, 431. 
Paracotoin, 502. 
Paracyanogen, 280, 282. 



772 



INDEX. 



Paradol, 418. 
Paraffin, 398. 

oil, 398. 

series of hydrocarbons, 394, 
396. 

wax, 398. 
Paraffinic acid, 399. 
Paraffins, gaseous, 396. 

hard, 399. 

monohydroxyl derivatives of, 
436. 

relations to olefines and acety- 
lenes, 410. 

soft, 398. 

solid, 399. 
Paraffinum durum, 398. 

liquidum, 398. 

molle, 398. 
Paraguay tea, 542. 
Parahydroxybenzoic aldehyde, 494. 
Paraldehyde, 485. 
Paraldehydum, 485. 

impurities in, 716. 
Parallin, 507. 
Parapeptone, 551. 
Para-phenetol-carbamide, 431. 
Paratartaric acid, 320. 
Pareirse radix, 533. 
Pari cine, 533. 
Parietinic acid, 338. 
Parigenin, 507. 
Parilla, 533. 
Paris blue, 556. 

red, 554. 
Particles, elementary, 36. 
Patent sugar, 469. 
Pearlash, 62. 
Pearl barley, 473. 

sago starcb (fig.), 475. 

white, 252. 
Pear wine, 441. 
Pectin, 479. 

Pelargonate of ethyl, 407. 
Pelargonic acid, 490. 
Pelargonium, 418. 
Pelletierine, 359. 
Pellitory-root, 425. 
Pelosine, 533. 
Pennyroyal, American oil, 418. 

oil, 419. 
Pennywort, Indian, 509. 
Pentachloride of antimony, 181. 
Pentads, 124. 
Pentane, 398. 
Peutathionic acid, 346. 
Penthydric alcohols, 465. 
Pentylic acid, 490. 

alcohol, 449. 
Pepper, black, 541. 



Pepper, Cayenne, 534. 

cubeb, 541. 

long, 541. 

Melegueta, 418. 

oil of, 541. 

resin of, 541. 

white, 541. 
Peppermint oil, 418. 
Pepo, 510. 
Pepsin, 550. 
Pepsi num, 550. 

impurities in, 716. 

saccharatum, 551. 

vegetable, 551. 
Peptone, 550, 551. 
Peptones in urine, 574. 
Per-, meaning of, 148. 
Perbromates, 271. 
Percha tree, 420. 
Perch lorate of potassium, 295. 
Perchloric acid, 295. 
Perchloride of gold, 246. 

iron, 148. 

mercury, 201. 

platinum, 248. 

tin, 242. 
Perfumes, 415. 
Perhydrate of iron, 150. 
Periodic law, 380. 
Periodide of ammonium, 273. 

mercury, 273. 

potassium, 273. 
Permanganate of potassium, 77, 232. 
standard solution of, 652. 
vol. est. of, 635. 
Pernitrate of iron, 157. 
Peroxide of barium, 103. 

hydrogen, 103, 353. 

iron, 152. 

hydrated, 153. 

lead, 212. 

nitrogen. 289, 290. 
Perry, 441. 
Persian berries, 553. 
Personne's solution, 644. 
Persulphate of iron, 151. 

mercury, 200. 
Persulphide of hydrogen, 303. 
Peru, balsam of, 422, 495. 
Peruvine, 495. 
Petalite, 227. 
Petit-grain oil, 416. 
Petrolatum, 398. 

liquidum, 398. 

impurities in, 716. 

molle, 398. 

impurities in, 716. 

spissum, 398. 

impurities in, 716. 



INDEX. 



773 



Petroleine, 398. 
Petroleum benzin, 398. 

ether, 398. 

gas, 397. 

light, 398. 

soft, 398. 

spirit, 398, 430. 

testing, 413. 
Pettenkofer's test for presence of 

bile, 553. 
Peumus boldus, 416. 
Pewter, 185, 210, 241. 
Phseoretine, 338. 
Pharaoh's serpents, 357. 
Pharbitis nil, 505. 
Pharbitisin, 505. 

Pharmaceutical Society of Great 
Britain, examinations of, 14. 
Pharmacy, 15. 
Pharmacognosy, 15. 
Pharmacology, 15. 
Phellandrene, 412. 
Phellandrium aquaticum, 412. 
Phenacetin, 431. 
Phenacetinum, 431 (table) 544. 
Phenasonum, 431 (table) 544. 
Phenic acid, 452. 

alcohol, 452. 
Phenocoll, 431. 
Phenoene, 429. 
Phenol, 452. 

carbamine (table), 544. 

constitution of, 454. 

isonitrile (table), 544. 

salicylic, 492. 
Phenol-mercury, 454. 
Phenolphthalein, 434, 497, 635. 
Phenols, 452. 

Phenol-sulphonic acid, 445, 454. 
Phenylacetamide, 431. 
Phenylamine, 431, 514. 
Phenylates, 454. 
Phenylcarbinol, 456. 
Phenyl-dimethyl-pyrazolon, 431. 
Phenyl group, 431. 
Phenylmethyl ketone, 498. 
Phenyl salicylate, 492. 
Phosphate of ammonium, 95. 

barium, 105, 332. 

calcium, 106, 112, 357. 

iron, 146, 156, 331. 

magnesium and ammonium, 
122, 331. 

from oxalates and 
ferric oxide, separation of, 
375. 

in bones, 112, 327. 

silver, 219. 

sodium, 88. 



Phosphate of sodium, how prepared 
from phosphate of calcium, 
113. 
Phosphates, 327. 

analytical reactions of, 330. 
quantitative estimation of, 684. 
Phosphites, 352. 
test for, 352. 
Phospho-antimonic acid, 571. 
Phosphomolybdic acid, 331, 571. 
Phosphorated oil, 326. 
Phosphoretted hydrogen, 343. 
Phosphoric acid, 25, 327, 352. 
diluted, 329. 
glacial, 330. 
meta-, 330. 
ortho-, 330. 
pyro-, 330. 

quantitative estimation of 
free, 684. 
vol. est. of,. 638. 
anhydride, 25, 330. 
Phosphorous acid, 351, 352. 
Phosphorus, 25, 327. 
acids of, 352. • 
bromide of, 329. 
combustion of, 25. 
derivation of word, 32. 
detection of, in organic mix- 
tures, 566. 
impurities in, 716. 
iodide, 329. 
granulated, 328. 
molecular weight of, 328. 
pill, 328. 

properties of, 25, 328. 
red or amorphous, 328. 
trihydride, 343. 
Phosphotungstic acid, 571. 
Phthaleins, 432. 
Phthalic acid, 336, 432, 496. 
anhydride, 497. 
series of acids, 496. 
Phyllocyanin, 457. 
Phylloxanthin, 457. 
Physical isomerides, 482. 
Physics, 43. 
Physostigma, 540. 

impurities in, 716. 
Physostigmina, 540. 
Physostigminse salcylas, 540 
impurities in, 716. 
sulphas, 540. 

impurities in, 716. 
Physostigmine, 540. 

salicylate, 540. 
Phytolacca fructus et radix, 510. 
Phytolaccin, 510. 
Picoline, 513. 



774 



INDEX. 



Picric acid, 454, 554. 
Picrotin, 506. 
Picrotoxin, 506, 544. 
Picrotoxinum, 506. 

impurities in, 716. 
Pigment, 553. 
Pi amentum nigrum, 557. 
Pills, 589. 
Pilocarpidine, 540. 

impurities in, 716. 
Pilocarpine nitras, 540. 

hydrochloras, 540. 
Pilocarpus, 540. 
Pilocarpus pennatifolius, 540. 
Pilula aloes et ferri, 144. 

ferri carbonatis, 145. 
compositse, 146. 
iodidi, 31. 

phosphori, 328. 

plumbi cum opii, 211. 
Pimaric acid, 423. 
Pimento oil, 416. 
Pimpinella anisum, 413. 
Pine-apple, essence of, 407. 

wool, 413. 
Pinene, 412. 
Pinic acid, 423. 
Pink saucers, 555. 

the common, 507. 
Pins, 242. 
Pint, 608. 
Pinus, 412, 423. 

larix, 359, 412. 
Pipe-clay, 139. 
Piperazine, 512. 
Piper nigrum, 541. 
Piperia, 541. 
Piperic acid, 541. 
Piperidia, 541. 
Piperidine, 541. 
Pipeline, 541. 
Piperinum, 541. 

impurities in, 716. 
Pipette, 272. 

Pistachia terebinthus, 412. 
Pitch, 427. 

Burgundy, 425. 
Pituri, 540. 
Pix burgundica, 425. 

Uquida, 413, 426. 
Plantago ispaghula, 479. 
Plants and animals, complementary 

action of, on air, 19. 
Plaster of ammoniacum and mer- 
cury, 195. 

mercury, 195. 

Paris, 106. 
Plasters, 213, 423. 
Plastic elements of nutrition, 548. 



Plastic sulphur, 301. 
Platinic chloride, 248. 

salts, 248. 

sulphide, 248. 
Platinous chloride, 248. 

salts, 248. 
Platinum, 247. 

analytical reactions of, 248. 

and ammonium, chloride of, 99, 
249. 

and lithium, chloride of, 228. 

and potassium, chloride of, 79, 
249. 

and sodium, chloride of, 249. 

black, 248. 

derivation of word, 34. 

-foil, 247. 

perchloride, 248. 

residues, to recover, 249. 

spongy, 249. 
Pleurisy-root, 509. 
Plumbago, 30. 
Plumbi acetas, 211. 

impurities in, 716. 

carbonas, 211. 

impurities in, 716. 

emplastrum, 213. 

iodidum, 213. 

impurities in, 716. 

nitras, 212. 

impurities in, 716. 

oxidum, 210. 

impurities in, 716. 

subacetatis, liquor, 212. 
Plumbic acetate, sulphate, etc. 
Vide Salts of Lead. 

peroxide, 212. 
Plumbum, 30. 
" Plummer's pill," 203. 
Pocula emetica, 180. 
Podophyllin, 425. 
Podophyllotoxin, 425. 
Podophyllum, 425. 

resina, 425. 
Podophyllum resin, 425. 
Poisonous alkaloids, 566. 
Poisons of cheese, milk, fish, etc., 
513, 571. 

antidotes to. See Antidotes. 

detection of, in organic mix- 
tures, 562, et seq. 
Pokeberry and root, 510. 
Polybasic acids, 264. 
Polybasylous radicals, 264. 
Polychroite, 554. 
Polygala senega, 508. 
Polygalic acid, 508. 
Polyhydroxyl derivatives of hydro- 
carbons, 465. 



t 



INDEX. 



775 



Polymerides, 481. 
Polymerism, 480. 
Polymers, 481. 
Polymorphism, 482. 
Polymorphous bodies, 482. 
Polysulphide of calcium, 303. 
Pomegranate-rind, 359. 
Pomegranate-root bark, 359. 
Poppy capsules, 516. 
Porcelain, 355. 
Porridge, 473. 
Porter, 441. 
Portland cement, 355. 
Port wine, 441. 
Positive pole, 245. 
Potash, acetate. 70. 

alum, 139. 

bicarbonate, 71. 

bichromate, 238. 

bitartrate, 79. 

carbonate, 62. 

caustic, 63, 67. 

to prepare pure, 68. 
solution of, 63. 

chlorate, 293. 

citrate, 73. 

effervescing solution of, 73. 

iodate, solution of, 296. 

nitrate, 73, 285. 

permanganate, 77, 231. 

prussiate, red, 343. 
yellow, 280, 340. 

sulphate, 75. 

sulphurated, 68. 

tartrate, 74. 
acid, 79. 
and soda, 87. 

volumetric estimation of solu- 
tions of, 631. 

volumetric solutions of, 636. 
Potash-water, 72. 
Potashes, 62. 
Potassa, 68. 

impurities in, 717. 

cum calce, 68. 

sulphurata, 68. 
Potassse effervescens, liquor, 72. 

liquor, 63, 67. 

to prepare pure, 67. 

sulphuratse unguentum, 69. 
Potassic hydrate, carbonate, etc. 

Vide Salts of Potassium. 
Potassii acetas, 70, 242. * 

impurities in, 717. 

bicarbonas, 71. 

impurities in, 717. 

bichromas, 238. 

bitartras, 74, 79, 320. 
impurities in, 717. 



Potassii bromidum, 77. 

impurities in, 717. 
carbonas, 62. 

impurities in, 717. 
chloras, 293. 

impurities in, 717. 
citras, 73. 

impurities in, 717. 
cyanidum, 280. 

impurities in, 717. 
et sodii tartras, 74, 87, 320. 

impurities in, 717. 
ferricyanidum, impurities in, 

718. 
ferrocyanidum, 280, 340. 
hypophosphis, 344. 

impurities in, 717. 
iodidum, 74. 

impurities in, 718. 
nitras, 73, 285. 

impurities in, 718. 
permanyanas, 79, 231. 

impurities in, 718. 
sulphas, 73, 288. 

impurities in, 718. 
Potassio-citrate of iron, 154. 
Potassio-tartrate of antimony, 181. 

iron, 154. 
Potassium, 59. 
acetate, 70. 

acid carbonate. Vide Bicar- 
bonate, 
alizarate, 434. 
analytical reactions of, 78. 
and platinum chloride, 79, 249. 
and sodium tartrate, 87, 320. 
angelate, 413. 
anhydrochromate, 238. 
bicarbonate, 71. 
bichromate, 238. 
borotartrate, 334. 
bromate, 79. 
bromide, 79, 270. 

volumetric estimation of, 
642. 
carbonate, 62. 
chlorate, 16, 291. 
chloride, 78. 
chromate, 105. 
citrate, 73. 
cobalticyanide, 235. 
cyanate, 338. 
cyanide, 280. 

volumetric estimation of, 
641. 
derivation of word, 32. 
ferrate, 143. 
ferricyanide, 341. 
ferrocyanide, 280, 341. 



776 



INDEX. 



Potassium flame, 80, 101. 
hypophosphite, 344. 

volumetric estimation of, 
655. 
hydrate, 63. 

to prepare pure solution, 
68. 
standard solution, 636. 
. iodate, 74, 296. 
iodide, 74, 274. 

volumetric estimation of, 
643. 
manganate, 77, 231. 
myronate, 451. 
nitrate, 73, 285. 
nitrite, 350. 
oleate, 459. 
perchlorate, 295. 
periodide, 273. 
permanganate, 77, 231. 

volumetric estimation of, 
652. 
preparation of, 63. 
properties of, 63. 
quantitative estimation of, 659. 
quantivalence of, 63. 
red chromate, 238. 

volumetric solution of, 648. 
red prussiate, 342. 
salts, analogy of, to sodium 

salts, 89. 
sodium and ammonium, sepa- 
ration of, 101. 
sources, 61. 
succinate, 356. 
sulphate, 73, 288. 
sulphide, 68. 
sulphocyanate, 356. 

volumetric solution of, 658. 
tartrate, 74, 320. 

acid, 62, 74, 79, 318. 
tri-iodide, 273. 
yellow chromate of, 105, 238. 
prussiate of, 280, 341. 
Potato, 472, 475. 
oil, 449. 

starch (fig.), 475. 
Poultices, 589. 
Pound, 608. 

Powder, bleaching, 114. 
Powders, 589. 
soda, 88. 

specific gravity of, 617. 
Practical analysis, 100. 
Precipitant, 79. 
Precipitate, 79. 

Precipitated carbonate of lime, 108. 
chalk, 19. 
sulphur, 303. 



Precipitates soluble in solutions of 
salts, 224. 
to wash, 109. 
to weigh, 681. 
Precipitation, 79. 

fractional, 378. 
Preparations of the pharmacopoeias, 
chemical, 589. 

galenical, 589. 
Prepared calamine, 132. 

carbonate of calcium, 113. 
chalk, 143. 
lard, 462. 
suet, 462. 
Pressure, correction of volume of 
gas for, 619. 
gauges, 594. 
Prickly ash, 533. 
Primary alcohols, 436. 
Principles, 35, et seq. See, also, 
"Analogy," "Atomic," 

"Chemical Action, Affinity, 
and Combination," " Classi- 
fication," " Constitution," 
"Formulae," "Fractional," 
" Homology," " Indestructi- 
bility," "Laws," "Molecu- 
lar," "Notation," "Nomen- 
clature," "Solution," "Sub- 
stitution," "Structure," 
"Valency," etc. 
Printer's ink, 556. 
Prismatic nitre, 285. 
Proof spirit, 442. 
Propane, 397. 

Propanetricarboxylic acid, 498. 
Propargyl alcohol, 411. 
Propenyl, ^57. 
alcohol, 457. 
hydrate, 457. 
Propepsin, 550. 
Propeptone, 551, 574. 
Prophetin, 503. 
Propione, 498. 
Propionic acid, 488. 
Proportions, atomic, 51, 198. 
constant, 48. 
multiple, 49, 198. 
reciprocal, 50. 
Propylamine, 512. 
Propylene, 408. 
Propylformic acid, 488. 
Propylic acid, 488. 

alcohol, 457. 
Propylmethylbenzene, 432. 
Proteid principles, 544. 
Protocatechuic aldehyde, 364. - 
Protococcus vulgaris, 465. 
Protopine, 518, 541. 



INDEX. 



777 



Proximate analysis, 688. 
Prune, 469. 
Prunum, 469. 
Prunus serotina, 500. 

virginiana, 500. 
Prussian blue, 162, 342. 
Prussiate of potash, red, 342. 

yellow, 280, 341. 
Prussic acid, 280. 
Pseudaconitine, 530. 
Pseudojervine, 539. 
Pseudomorphine, 518. 
Pseudoxanthine, 513. 
Pterocarpi lignum, 555. 
Pterocarpin, 555. 
Pterocarpus marsupium, 359. 

santalinus, 419, 555. 
Ptomaines, 513, 571. 
Ptyalin, 586. 
Ptychotis ajowan, 415. 
Piice-colored oxide of lead, 212. 
Puddling iron, 142. 
Pulezone, 419. 
Pulvis algarothi, 181. 

angelicus, 181. 

antimonialis, 184. 

effervescens, 88. 321. 

effervescentes compositus, 321. 

ipecacuanhx et opii, 537. 

morphinse compositus, 517. 

sodse tartaratse effervescens, 321. 
Purified ox-bile, 552. 
Purple of Cassius, 247. 

foxglove, active principle in, 
502. 

pigment, 362. 
Purpurin, 579. 
Purrate of magnesium, 553. 
Purree, 553. 
Pusch's test for citric and tartaric 

acids, 326. 
Pus in urine, 585. 
Putrescine, 513. 
Putty-powder, 243. 
Pvrethric acid, 425. 
Pyrethrin, 425, 541. 
Pyrethrum, 425. 

carneum, 425. 
Pyridine, 513. 

derivatives, 513, 536, 541. 
Pyrites, copper, 190. 

iron, 142. 
Pyroarsenate of sodium; 169. 
Pyroarsenates, 169. 
Pyroborate of sodium, 333. 
Pyrocatechin, 455. 
Pyrocbromate of potassium, 238. 
Pyrogallic acid, 360, 465, 494. 

use of, in gas analysis, 361, 



Pyrogallol, 360, 465, 494. 

impurities in, 718. 
Pyroligneous acid, 297. 
Pyrolusite, 231. 
Pyromellitic acid, 498. 
Pyrometers, 598. 
Pyromorpbite, 333. 
Pyropborus, 159. 
Pyrophosphates, 353. 
Pyrophosphoric acid, 330, 353. 
Pyrosulphuric acid, 310. 
Pyrotartaric acid, 497. 
Pyrovanadates, 332. 
Pyroxylic spirit, 437. 
Pyroxylin, 479. 
Pyrrol, 513. 
Pyrus cydonia, 500. 

QUADRIVALENCE, 56. 

Qualitative analysis, 125, 370, 557. 
Quantitative analysis, 598, et seq. 

determination of atmospheric 
pressure, 593. 

of temperature, 594. 
of weight, 600. 
Quantivalence, 56, 123. 

of acidulous radicals. 67, 124, 
264. 

of atoms, definition of, 57. 

variation in, 139. 
Quartz, 354. 
Quassise lignum, 506. 
Quassin, 506. 
Quebracbine, 530. 
Quebracho bark, 530. 
Queen's root, 542. 
Quercitrin, 554. 
Quercitron, 554. 
Quercus cortex, 358. 

tinctoria, 554. 
Quevenne's iron, 158. 
Quicklime, 107. 
Quillaic acid, 508. 
Quillaja, 508. 

saponaria, 508. 
Quinamiue, 526. 
Quinate of quinine, 521. 
Quince-seed, 479, 500. 
Quinia. See Quinine, 521. 
Quinic acid, 521. 
Quinicine, 526. 
Quinidine, 524. 

sulphas, 525. 
Quinina, 696. 

impurities in, 718. 
Quininse hydrochloras, 522. 
impurities in, 718. 

hydrobromas, 523. 

impurities in, 718. 



778 



INDEX. 



Quinines bisulphas, 522. 

impurities in, 718. 

sulphas, 522. . 

impurities in, 718. 

valerianas, 523. 

impurities in, 719. 
Quinine, 521. 

amorphous, 526. 

analytical reactions of, 523. 

bisulphate, 522. 

citrate, 523. 

of iron and, 55, 522. 

hydrobromate, 523. 

hydrochlorate, 522. 

ibdosulphate, 523.. 

kinate, 521. 

quantitative estimation of, 693. 

quinate, 521. 

sulphates, 522. 

valerianate, 523. 

wine, 522. 
Quiniretiu, 526. 
Quinlan's test for presence of bile, 

553. 
Quinoidine, 526. 
Quinoline, 514. 
Quinone, 501, 521. 
Quinquivalence, 56. 

of atoms, definition of, 59. 

Eacemic acid, 320. 
Radicals, acidulous, 67, 123. 
formulse of, 67. 

basylous, 60, 123. 

definition of, 67. 

organic, 392. 
Eai, 451. 
Baisins, 318, 467. 
Eaoult's experiments, 623. 
Easpberry, sugar in, 467. 
Eatafia, 441. 
Eational formula, 390. 
Eattan palm, 424. 
Eatti, 504. 
Eeactions, analytical, 62. 

synthetical, 62. 
Eeagents, list of, xiii. 
Eeal alcohol, 442. 
Eealgar, 168. 

Reaumur's thermometer, 596. 
Reciprocal proportions, law of, 50. 
Eectification, 129. 
Eectified oil of turpentine, 412. 

spirit, 129, 442. 
Eed, Chinese, 554. 

chromate of potassium, 238. 

chrome, 554. 

coloring-matter, 554. 

corpuscles in blood, 546. 



Eed earth, 555. 

enamel colors, 555. 

gravel, 579. 

gum, 418. 

haematite, 142. 

iodide of mercury, 198. 

lead, 212. 

litmus-paper, 96. 

ochre, 555. 

oxide of iron, 142, 153, 555. 
mercury, 204. 

Paris, 554. 

phosphorus, 328. 

poppy-petals, 555. 

precipitate, 204. 

prussiate of potash, 341. 

rose-petals, 555. 

sandal-wood, 419, 555. 

sanders- wood, 420, 555. 

sulphide of mercury, 204. 

Venetian, 153. 
Reduced indigo, 291. 

iron, 153. 

volumetric estimation of, 
654. 
Eeducing flame, 135. 
Eeinsch's test for arsenum, 172. 
Eelative weight of hydrogen and 

oxygen, 24. 
Eemijia bark, 526. 
Eennet, 546. 
Reseda luteola, 554. 
Resin, 412, 423. 

arnica, 423. 

cannabis, 423. 

capsicum, 424. 

castor, 424. 

ergot, 424. 

guaiacum, 504. 

Indian hemp, 423. 

jalap, 505. 

kaladana, 505. 

kamala, 425. 

kousso, 424. 

mastic, 424. 

mezereon, 425. 

oils, 422. 

pepper, 425, 541. 

podophyllum, 425. 

pyrethrum, 425. 

rottlera, 425. 

scammony, 508. 

soap, 462. 
Besina, 423. 

copaibee, 425. 

jalapse, 505. 

impurities in, 719. 
Eesins, 423. 
Eesorcin, 423. 



INDEX. 



779 



Resorcinum, 456. 

impurities in, 719. 
Respiratory materials of food, 548. 
Retort, 128. 
Rhamni frangula cortex, 338. 

Purshiani cortex, 338. 

succus, 502, 556. 
Rharunin, 554. 
Rbamnose, 554. 
RJiamnus catharticus, 556. 

frangula, 503. 
Rhaponticin, 338. 
Rhatany-root, 359. 
Rheic acid, 338. 
Rhein, 338. 
Rheum, 338. 
Rheumin, 338. 
Rhodium, 726. 
Rhoeadas petala, 555. 
Rhceadine, 518. 
Rhubarb, oxalate of calcium from, 

316. 
Rhubarbaric acid, 338. 
Rhubarbarin, 338. 

coriaria, 360. 
Rhus cotinus, 553. 

glabra, 360. 

toxicodendron, 361. 
Rice, 473. 

starch (fig.), 475. 
Ricin, 464. 
Ricinine, 464. 

Ricinoleate of glyceryl, 464. 
Ricinoleine, 464. 
Ringworm powder, 338. 
Roccella tinctoria, 465. 
Roche alum, 140. 
Rochelle salt, 74, 87, 320. 
Rock alum, 140. 

salt, 81. 
Rohun-bark, 510. 
Roll sulphur, 301. 
Roman cement, 355. 
Rosa canina, 364. 
Rosx caninse fructus, 469. 

centifolise petala, 419, 555. 

gallicse petala, 555. 
Rose, 419, 469, 555. 

oil, 419. 
Roseaniline, 431, 557. 
Rosemary oil, 419. 
Rose-petals, 419, 555. 
Rose-water, 414, 419. 
Rosin, 412, 423. 
Rotang palm, 424. 
Rotten-stone, 138. 
Rottlera tinctoria, 425. 
Rottlerin, 425. 
Rouge, animal, 337. 



Rouge, mineral, 153, 555. 

vegetable, 555. 
Rubia tinctoria, 554. 
Rubianic acid, 554. 
Rubidium, 726. 
Rubijervine, 439. 
Rubus, 360. 
Ruby, 138. 
Rue oil, 419. 
Rum, 441. 
Rumex, 338. 
Rumicin, 338. 
Rust of iron, 143. 
Rutate of glyceryl, 462. 
Ruthenium, 726. 
Rutic acid, 462. 

aldehyde, 419. 

radical, 462. 

Sabadilla, 543. 
Sabadilline, 543. 
Sabadine, 543. 
Sabadinine, 543. 
Sabatrine, 543. 
Sabina, 419. 

Saccharated carbonate of iron, 145. 
volumetric estimation 
of, 653. 
Saccharic acid, 472. 
Saccharin, 446. 

soluble, 446. 
Saccharine, 469. 
Saccharometer, 703. 
Saccharometry, 702. 
Saccharomyces cerevisise, 440. 
Saccharons, 469. 
Saccharoses, 467, 469. 
Saccharnm lactis, 471. 

impurities in, 719. 

purificatum, 469. 

ustum, 471. 
Sacred bark, 338. 
Safety lamp, 24. 

tube, 266. 
Satflower, 555. 
Saffranin, 554. 
Saffron, 554. 

bastard, 555. 

dyer's, 555. 

oil of, 554. 
Safrol, 420. 
Sage, oil of, 419. 
Sago, 473. 

starch (fig.), 475. 
Sal ammoniac, 91. 

prunella, 286. 

volatile, 94. 
Salep, 479. 
Salicin, 456, 506. 



780 



INDEX. 



Salicinum, 506. 

impurities in, 719. 
Salicylate of methyl, 407, 492. 

phenyl, 492. 

sodium, 493. 
Salicylic acid, 407, 457, 492. 

aldehyde, 407, 457, 493. 
Salicylol, 407. 
Salicylous acid, 407. 
Saligenin, 492, 506. 

alcohols, 457. 
Saligenol, 453, 506. 
Saliretin, 506. 
Saliva, 586. 
Salol, 492. 
Salol, 492. 

impurities in, 719. 
Salseparin, 507. 
Salt cake, 312. 

common, 81. 

definition of a, 60. 

Epsom, 118. 

of sorrel, 316. 

Eochelle, 74, 87, 320. 

rock, 81. 
Saltpetre, 286. 

Chili, 286. 
Salts, acids, 73, 74, 302. 

action of the blowpipe on, 373. 
of heat on, 372. 
of sulphuric acid on, 372. 

alkyl, 484. 

analogies of, 90. 

analysis of insoluble, 376. 

constitution of, 61, 124, 262, 286, 
299, 378. 
resume, 378. 

double, 79. 

formation of, 79. 

nomenclature of, 73, 76. 

of ammonium, volatility of, 99. 

of iron, nomenclature of, 143. 

physical properties of, 371. 

substitution of, for each other, 
89. 

table of the solubility or insol- 
ubility of, in water, 368. 
Salviol, 419. 
Sambucene, 419. 
Sambuci flores, 419. 
Sand, 355. 
Sandal- wood, oil of, 419. 

red, 555„ 

white, 419. 

yellow, 419. 
Sand-bath, 29. 
Sand-stone, 354. 
Sand-tray, 29. 
Sanders-wood, red, 555. 



Sanguinaria canadensis, 541. 
Sanguinarine, 541. 
Santalin, 555. 
Santalum album, 419. 
Santonic acid, 507. 
Santonica, 507. 
Santonin, 507. 
Santoninum, 507. 

impurities in, 719. 
Santoniretin, 507. 
Sap-green, 556. 
Sapan-wood, 554. 
Sapo, 461. 

impurities in, 719. 

animalis, 461. 

durus, 461. 

kalinus venalis, 461. 

mollis, 461. 

viridis, 461. 
Sapogenol, 507. 
Saponetin, 507. 
Saponification, 462. 
Saponin, 507. 
Sapotoxin, 508. 
Sapphire, 138. 
Saprine, 513. 

Sarcina ventriculi in urine, 587. 
Sarcocephalus esculentus, 424. 
Sarcolactic acid, 348, 489. 
Sarkine, 515. 
Sarkosine, 512. 
Sarracenia purpurea, 543. 
Sarsaparilla, 507. 
Sassafras oil, 420. 

radix, 420. 

swamp, 509. 
Sassafrol, 420. 
Saturated hydrocarbons, 391. 

solutions, boiling-points of, 596. 
Saturating . power of citric acid, 
325. 

of tartaric acid, 321. 
Saturation, 71. 

tables, 724. 
Saturn, 211. 
Saturnine colic, 211. 
Savin oil, 419. ' 
Saxon blue, 555. 
Saxony blue, 555. 

Scale compounds of iron, 154, et seq. 
Scammonise radix, 508. 

resina, 508. 
Scammonin, 508. 
Scammoniol, 508. 
Scammonium, 508. 

impurities in, 719. 
Scammony, resin of, 508. 
Scandium, 726. 
Scents, 415. 



INDEX. 



781 



Scheele's green, 178. 

Schist, 138. 

Schcenocaulon officinale, 543. 

Schonbein's test for hydrocyanic 

acid, 284. 
Schweinfurth greeu, 177. 
Science of Chemistry, 14. 
Scilla, 470, 508. 
Scillin, 508. 
Scillipicrin, 508. 
Scillitin, 508. 
Scillitoxin, 508. 
Sclerotic acid, 424. 
Sclerotinic acid, 424. 
Scoparin, 542. 
Scoparius, 542. 
Scopoleine, 532. 
Scopoletin, 532. 
Scopola Japonica, 515, 532. 
Scutellaria, 510. 
Scyllite, 469. 
Sea-salt, 81. 
Sebacate of ethyl, 407. 
Secale cerale, 424. 
Secondary alcohols, 436. 
Sediments, urinary, 579. 

microscopic examinations 
of, 581. 
Seed-lac, 555. 
Seidlitz powder, 321. 
Selenic acid, 302. 
Selenion, 726. 
Selenious acid, 320. 
Selenium, 726. 

Semina cardamomi majoris, 418. 
Senegse radix, 508. 
Senna, 501. 

Seuna of Alexandria, 501. 
Sepia, 556. 
Sepiadse, 556. 
Serolin, 546. 
Serpentaria, 510. 
Serpent's excrement, 580. 
Sesame oil, 464. 
Sesamum indicum, 464. 
Sesquiterpene, 412. 
Sevum prseparatum, 462. 
Sexivaleuce, 57. 
Shale, 138. 
Shark-liver oil, 465. 
Shellac, 555. 
Shell-fish poison, 513. 
Sherry wine, 441. 
Shot, 210. 
Siam benzoin, 364. 
Sidee, 424. 
Sienna, 556. 

Sifting an aid to analysis, 372, 378. 
Silica, 354. 
34 



Silicate of aluminium, 354. 

calcium, 354, 355. 

lithium, 227. 

magnesium, 354. 
Silicates, 354. 

quantitative estimation of, 687. 

tests for, 355. 
Silicic acid, 354, 355. 

au hydride, 354. 
Siliciuretted hydrogen, 355. 
Silicon, chloride, 356. 

derivation of word, 34. 

fluoride, 342, 356. 

hydride, 355. 

oxide, 355. 
Silver, 216. 

ammonio-nitrate, 177, 207. 

analytical reactions of, 219. 

antidotes, 220. 

arsenate, 177, 219. 

arsenite, 177. 

bromide, 220, 271. 

chloride, 217. 

chromate, 220. 

citrate, 326. 

coinage, 216, 617. 

cyanide, 220, 283. 

derivation of word, 35. 

estimation of, by cupellation, 
676. 

extraction of, 216. 

fulminate, 219. 

German, 171, 236. 

iodide, 228, 275. 

nickel, 236. 

nitrate, impure, 216. 
pure, 217. 
toughened, 218. 
volumetric solution of, 639. 

oxalate, 317. 

oxide, 219. 

phosphate, 219. 

pure, 217. 

quantitative estimation of, 675. 

standard solution of nitrate of, 
639. 

sulphate, 216. 

sulphide, 219. 
native, 216. 

sulphite, 307. 

tartrate, 322. 

tree, 220. 
Sinalbin, 451. 
Sinapis, 451. 

nlbse, 451. 

impurities in, 719. 

juncea. See Brassica. 

nigrse, 451. 

impurities in, 719. 



782 



INDEX. 



Sinapisine, 451. 
Sinigrin, 451. 
Siuistrin, 507. 
Siphon, 110. 
Size, 549. 
Skullcap, 510. 
Slaked lime, 107. 
Slate, 138. 
Smalt, 235, 555. 
Smilacin, 507. 
Snake-root, black, 509. 
Virginia, 510. 
Soap, ammonium, calcium, Castile, 
green, hard, Marseilles, mot- 
tled, potassium, sodium, soft. 
461. 

curd, 461. 

marine, 462. 

resin, 462. 

yellow, 462. 
Soap-bark, 508. 
Soap-stone, 557. 
Soap-wort, 507. 
Socaloin, 435. 
Socatrine aloes, 434. 
Soda, 82, 312. 

acetate, 83. 

alum, 139. 

arsenate, 169. 

ash, 89, 312. 

benzoate, 337. 

bicarbonate, 83, 313. 

carbonate, 84, 89, 312. 

caustic, 82. 

chlorinated, 87. 

citro-tartrate, 88. 

hydrate, 82. 

hypochlorite, 87. 

hypophosphite, 344. 

hyposulphite, 345. 

lime, 691. 

nitrate, 82, 286. 

phosphate, 88, 113. 

powders, 88. 

salicylate, 493. 

solution of chlorinated, 87. 

standard solution of, 639. 

sulphate, 267. 

sulphite, 306. 

sulphocarbolate, 454. 

valerianate, 362. 

volumetric estimation of, 632. 
solution of, 639. 
Soda, 82. 

impurities in, 719. 

tartarata, 74, 87, 319. 
Soda-water, 86. 

Sodic carbonate, etc. Vide Salts of 
Sodium. 



Sodii acetas, 83. 

impurities in, 719. 
arsenas, 169. 

impurities in, 719. 
benzoas, 337. 

impurities in, 719. 
bicarbonas, 83, 313. 

impurities in, 719. 
bisulphis, 306. 

impurities in, 720. 
boras, 333. 

impurities in, 720. 
bromidum, 88. 

impurities in, 720. 
carbonas, 84, 313. 

impurities in, 720. 

exsiccatus, 85. 
chloras, 294. 

impurities in, 720. 
chloratse, liquor, 87. 
chloridum, 81. 

impurities in, 720. 
citro-tartras effervescent;, 88. 
hypophosphis, 344. 

impurities in, 720. 
hyposulpMs, 345. 

impurities in, 720. 
iodidum, 88. 

impurities in, 720. 
nitras, 286. 

impurities in, 720. 
nitris, 351. 

impurities in, 720. 
phosphas, 113. 

impurities in, 721. 

effervescens, 88. 
salicylas, 493. 

impurities in, 721. 
silicatis, liquor, 355. 
sulphas, 267. 

impurities in, 721. 

effervescens, 88. 
sulphis, 306. 

impurity in, 721. 
sulphocarbolas, 454. 

impurity in, 721. 
valerianas, 362. 
Sodio-citrate of iron, 156. 
Sodium, 81. 
acetate, 83. 
acid carbonate, 83. 

sulphate, 265. 
analytical reactions of, 89. 
and aluminium double chloride. 

138. 
and platinum chloride, 249. 
and potassium, tartrate of, 87, 

318. 
arsenate, 169. 



INDEX. 



783 



Sodium arsenite, 168, 169. 
benzoate, 337. 
biborate, 333. 
bicarbonate, 83, 88, 313. 

chemically pure, 628. 

lozenges, 87. 
bisulphite, 306. 

volumetric estimation of, 
648. 
bromate, 77, 271. 
bromide, 88. 
carbonate, 81, 85, 313. 

chemically pure, 628. 

manufacture of, 88, 312. 
chlorate, 294. 
chloride, 81. 

pure, preparation of, 658. 

volumetric solution of, 657. 
cholate, 552. 
citro-tartrate, 88. 
derivation of word, 32. 
ethylate, 444. 
flame, 89, 101. 
glycocholate, 552. 
gravimetric estimation, 663. 
hydrate, 82. 
hypochlorite, 87. 
hypophosphite, 344. 

volumetric estimation of, 
654. 
hyposulphite, 345. 
iodide, 87. 
manganate, 232. 
metaborate, 333. 
nitrate, 81, 286. 
nitrite, 351. 
oxalate, 316. 
permanganate, 232. 
phosphate, 113. 

effervescent, 88. 

how prepared from phos- 
phate of calcium, 113. 
potassium, and ammonium, sep- 
aration of, 111. 
pyroarsenate, 169. 
pyroborate, 333. 
pyrophosphate, 353. 
quantitative estimation of, 663. 
salicylate, 493. 

salts, analogy of, to potassium 
salts, 89. 

sources of, 81. 
stannate, 243. 
sulphate, 267. 

effervescent, 88. 
sulphite, 306. 

volumetric estimation of, 
647. 
sulphycarbolate, 454. 



Sodium tartrate, 321. 
taurocholate, 552. 
valerianate, 362. 
Soft soap, 461. 
Soils, analysis of, 706. 
Solania, 541. 
Solanidine, 542. 
Solanine, 541. 
Solatium dulcamara, 541. 
tuberosum, 541. 

starch of (fig.), 475. 
Solazzi juice, 504. 
Solder, 210, 241. 
Solid,definition of, 58. 
fats, 462. 
potash, 68. 
Solids, to take the specific gravity 
of, 617, et seq. 
heavier than water, to take the 
specific gravity of, 617. 
Solubility of carbonic-acid gas in 
water, 87. 
of gases in water, 87. 
or insolubility of salts in water, 
table of, 368. 
Soluble cream of tartar, 334. 
glass, 355. 
saccharin, 445. 
starch, 477. 
substances, to take the specific 

gravity of, 617. 
tartar, 74. 
Solution of albumen, 544. 
ammonia, 92. 
ammonio-nitrate of silver, 177, 

207. 
ammonio-sulphate of copper, 
177. 

magnesium, 685. 
ammonium acetate, 92. 
chloride, 91. 
citrate, 95. 
oxalate, 95. 
antimony chloride, 180. 
arsenic, acid, 169. 
alkaline, 167. 
barium chloride, 103. 
bismuth and ammonium ci- 
trate, 254. 
boric acid, 334. 
bromine, 271. 
calcium chloride, 103. 
carbonate of ammonium, 94 w 
chlorinated lime, 115. 

soda, 87. 
chlorine, 28, 268. 
copper acetate, 192. 
ferric chloride, 149. 
fractional, 86, 89, 378. 



784 



INDEX. 



Solution of gold chloride, 246. 
perchloride, 246. 
gutta-percha, 421. 
iodine, 274. 
iron acetate, 154. 

perchloride, 149. 
pernitrate, 158. 
persulphate, 151. 
isinglass, 549. 
lead oxyacetate, 116, 211. 
lime, 108. 
litmus, 96, 636. 
mercury nitrate, 200. 
perchloride, 202. 
nature of, 139, 623. 
phosphoric acid, 228. 
platinum perchloride, 248. 
potash, 63. 

effervescing, 72. 
potassio-mercuric iodide, 658. 
potassium acetate, 70. 
ferricyanide, 341. 
ferrocyanide, 341. 
iodate, 296. 
red prussiate of potash, 341. 
soda, 82. 

sodium acetate, 83. 
ethylate, 443. 
phosphate, 113. 
silicate, 355. 
stannous chloride, 242. 
sulphate of calcium, 116. 
indigo, 291. 
iron, 151, 155. 
sulphydrate of ammonium, 96. 
tartaric acid, 320. 
tin chloride, 242. 
yellow chromate of potassium, 

105. 
zinc chloride, 133. 
Sonnenschein's process for poisonous 

alkaloids, 569. 
Soporine, 536. 
Sorbin, -ose, 469. 
Sorrel salt, 316. 
Soot, 30. 
Soubresauts, 282. 
Source of heat, 18. 
Sovereign, weight of the, 246. 
Soymida febrifuga, 510. 
Sozoiodol, 445. 
Sozolic acid, 445. 
Spanish liquorice, 504. 
Spar, fluor-, 106, 342. 

heavy, 102. 
Sparteine sulphas, 542. 

impurities in, 721. 
Sparteine, or Sparteia, 542. 
Spathic iron ore, 142. 



Spearmint oil, 419. 
Specific gravity, 613, et seq. 
bottles, 614. 
of gases, 619. 
of liquids, 614. 
of official liquids, 614. 
of oxygen, 24, 
of powders, 617. 
of solids, 616. 

lighter than water, 618. 
of soluble substances, 618. 
heat, 130, 622. 
weight, 613. 
Spectral analysis, 262, 560. 
Spectroscope, 262, 560. 
Specular iron ore, 142. 
Speculum metal, 241. 
Speiss, 236. 
Sperm oil, 450. 
Spermaceti, 450. 
Spermatozoa in urine, 586. 
Spigelina, 542. 

Spirsea ulmaria, 407, 493, 507. 
Spirit, methylated, 437. 
of French wine, 443. 
of myrcia, 441. 
of nitrous ether, 403. 

adulterated, 438. 
of turpentine, 412. 
of wine, 442. 
petroleum, 398, 430. 
proof, 442. 
pyroxylic, 437. 
rectified, 129, 442. 
wood-, 437. 
Spirits, 441. 

analysis of, 704. 
Spiritus xtheris, 449. 

compositus, 409. 
nitrosi, 351, 403. 

impurities in, 721. 
ammonix, 93. 

aromaticus, 94, 615. 
fcetidus, 94. 
armoracix compositus, 415. 
cajuputi, 415. 
cMoroformi, 401. 
cinnamomi, 415. 
frumenti, 441. 

impurities in, 721. 
juniperi, 415. 
lavandulx, 415. 
menthx piperitx, 415. 
myrcix, 441. 
myristicx, 415. 
rectificatus, 442. 
rosmarina, 415. 
tenuior, 442. 
vini gallici, 443. 



INDEX. 



785 



Spiritus vini gallici, impurities in, 721. 
Spodumeue, 227. 
Spogel-seeds, 479. 
Sponge, 548. 
Spongy platinum, 249. 
Spontaneous combustion, 159. 
Spotted cranesbill, 360. 
Spruce fir, 425. 
Spurge laurel, 425. 
Sqnalus carcharias, 465. 
Squill, 470, 479, 508. 
bulb, 508. 
vinegar of, 297. 
Standard solution of hyposulphite 
of sodium, 655. 
iodine, 645. 
nitrate of silver, 639. 
oxalic acid, 634. 
potash, 636. 
potassium permanganate, 

652. 
red chromate of potassium, 

648. 
soda, 639. 

sulphuric acid, 628. 
Staunate of sodium, 243. 
Stannates, 243. 
Stannic acid, 243. 
anhydride, 243. 
chloride, 242. 
oxide, 241, 243. 
sulphide, 244. 

anhydrous, 244. 
Stannous chloride, 242. 
solid, 242. 
hydrate, 244. 
oxide, 244. 
sulphide, 243. 
Stannum, 34. 
Staphisagrise semina, 536. 
Star-anise oil, 415. 
Starch, 472. 

action of diastase upon, 477. 

of dilute acids upon, 477. 
animal, 476. 
blue, 472. 
cellulose, 474. 

granules, composition of, 473. 
iodide of, 275, 473. 
mucilage of, 473. 
potato, 472. 
quantitative estimation of, 

702. 
soluble, 476. 
wheat, 472. 
white, 472. 
Starches, microscopy of, 474. 
Stas's process for poisonous alka- 
loids, 568. 



Stavesacre, 536. 
Steam-bath, 112. 
Stearic acid, 457, 488, 490. 
Stearine, 459. 
Stearoptens, 413. 
Steatite, 557. 
Steel, 142. . 

wine, 157. 
Stereochemical conceptions, 390, 

393. 
Stibines, 512. 
Stibium, 35. 
Stick lac, 555. 

liquorice, 504. 
Still, 127. 
Stillingia, 542. 
Stone coal, 241. 

red, 555. 

ware, 355. 
Storax, 422, 495. 
Stout, 441. 
Strammonii folia, 538. 

semina, 538. 
Strasburg turpentine, 412. 
Strawberry, sugar in, 467. 
Stream-tin, 241. 
Strontianite, 229. 
Strontii bromidum, 229. 

impurities in, 721. 

iodidum, 229. 

impurities in, 721. 

lactas, 229. 

impurities in, 721. 
Strontium, 229. 

analytical reactions of, 229. 

bromide, 229. 

volumetric estimation of, 
643. 

carbonate, 229. 

derivation of word, 34. 

flame, 230. 

nitrate, 229. 

sulphate, 229. 
Strophanthidin, 509. 
Strophanthin, 509. 
Strophanthus, 509. 
Structural formulae, 386. 
Structure, as indicated by — 

chemical " periodicity," 380. 
properties, 388, 396. 

density of gases and vapors, 53, 
55, 619. 

electricity, etc., 623. 

isomorphism, 55. 

specific heat, 622. 

substitution, 193. 
Structure of flame, 23. 

of molecules, 138, 139, 193, 387, 
392. 



786 



INDEX. 



Strychnine, or Strychnia, 527. 
impurities in, 721. 
analytical reactions of, 528. 
citrate, 527. 
in organic mixtures, detection 

of, 566. 
sulphate, 527. 

with brucine, estimation of, 700. 
Strychnos Ignatius, 527. 

nux vomica, 506, 527. 
Styracin, 495. 
Styrax prseparatus, 495. 
Styrol, 495. 
Sty rone, 495. 
Subacetate of copper, 192. 

lead, 211. 
Subcarbonate of iron, 145. 

bismuth, 253. 
Subchloride of iron, 149. 

mercury, 203. 
Suberate of ethyl, 407. 
Sublimation, 94. 
Sublimed sulphur, 301. 
Subnitrate of bismuth, 252. 
Substances readily deoxidized, 
quantitative estimation of, 
652. 
oxidized, quantitative estima- 
tion of, 645. 
Substitution, 172, 193, 394. 

products, 399. 
Sued, 589. 

Succinate of potassium, 336. 
Succinates, 336. 
Succinic acid, 336, 496. 
Succinum, 336. 
Succus limonum, 324. 
Sucrose, 469. 
Suet, 462. 

prepared, 462. 
Suffioni, 333. 

Sugar, action of alkali upon, 470. 
amount in various fruits, 468. 
barley, 471. 
brown, 469. 
candy, 469. 

detection of, in urine, 574. 
from caoutchouc, 469. 
eucalyptus, 471. 
fish, 469. 
gum arabic, 469. 
larch, 471. 
melitose, 471. 
mountain ash, 469. 
muscles, 469. 
starch, 469. 
Turkish manna, 471. 
grape-, 467. 
inverted, 468. 



Sugar, lichen, 465. 

lump, 469. 

maple, 471. 

milk, 471. 

moist, 469. 

of gelatin, 550. 

of lead, 211. 

patent, 469. 

quantitative estimation of, 702. 

sand, 471. 

syrup, 469. 

test for, 468. 
Sugar-cane, 468, 469. 
Suint, 460. 

Sulphamido-benzoates, 446. 
Sulphate of aluminium, 139. 
and ammonium, 139. 

ammonium, 91. 

barium, 103. 

beberine, 532. 

bismuth, 253. 

calcium, 106, 115. 

chromium, 238. 

cinchonidine, 525. 

cinchonine, 525. 

cobalt, 235. 

copper, 192. 

anhydrous, 192. 

cupr -diammon - diammonium, 
207. 

indigo, 291. 

iron, 144. 

and ammonium, 138, 144. 
solution of, 144. 

lead, 215. 

lithium, 228. 

magnesium, 118. 

mercury, 200, 201. 

morphine, 517. 

potassium, 73, 288. 

quinine, 522. 

sodium, 267. 

strontium, 229. 

strychnine, 527. 

zinc, 131. 
Sulphates, 307. 

analytical reactions of, 310. 

quantitative estimation of, 682. 
Sulphethylic acid, 447. 
Sulphide of allyl, 452. 

ammonium, 96. 

antimony, 179, 184. 

arsenum, 168, 176. 
native, 168. 

barium, 103. 

bismuth, 254. 

cadmium, 250. 

calcium, 115. 

cobalt, 235. 



INDEX. 



787 



Sulphide of iron, 31, 144, 161, 162. 

lead, 214. 

native, 210. 

manganese, 233. 

mercury, 207. 
native, 195. 

molybdenum, 331. 

nickel, 237. 

potassium, 68. 

silver, 219. 

native, 216. 

zinc, 136. 

native, 131. 
Sulphides, 301. 

analytical reactions of, 304. 

quantitative estimation of, 681. 
Sulphindigotic acid, 291. 
Sulphindylic acid, 291. 
Sulphite of barium, 307. 

calcium, 307. 

silver, 307. 

sodium, 306. 

zinc, 136. 
Sulphites, 305. 

analytical reactions of, 306. 

quantitative estimation of, 682. 
Sulpbocarbolates, 454. 
Sulphocarbolic acid, 454. 
Sulphocarbonates, 313. 
Sulphocarbonic anhydride, 314. 
Sulphocyanate of acrinyl, 451. 

allyl, 451. 

butvl, 415. 

iron, 162, 336. 

mercury, 357. 

tetryl, 415. 
Sulphocyanates, 336. 
Sulphocyanic acid, 336. 
Sulphocyanides, 357. 
Sulphocyanogen, 357. 
Sulphonal, 446 ; (table) 544. 
Sulphonic acids, 445. 
Sulphophenates, 454. 
Sulphopheuic acid, 454. 
Sulpbostannates, 244. 
Sulphoviuic acid, 310, 447. 
Sulphur, 30, 301. 

adulteration of, 304. 

alcohols, 445. 

allotropy of, 301. 

analogies, 177, 302. 

analytical reactions of, 304. 

arsenic in, 176. 

bromide, 304. 

chloride, 304. 

derivation of word, 32. 

estimation of, 681. 

ethers, 445, 447. 

flowers of, 301. 



Sulphur hypochloride, 304. 
iodide, 274. 
liver of, 68. 
lozenges, 303. 
milk of, 302. 

molecular weight of, 302. 
oxyacids, 346. 
plastic, 301. 
precipitated, 303. 
roll, 301. 
sublimed, 301. 
Sulphur lotum, 301. 

impurities in, 721. 
prsecipitatum, 303. 

impurities in, 721. 
sublimatum, 301. 

impurities in, 721. 
Sulphurated antimony, 182. 
lime, 115. 
potash, 68. 
Sulphurets. Vide Sulphides. 
Sulphuretted hydrogen, 97, 144, 301. 
Sulphuric acid, 307. 

antidotes to, 311. 
aromatic, 310. 
diluted, 310. 
estimation of, 638. 

in vinegar, 682. 
fuming, 310. 
Nordhausen, 310. 
organic mixtures, detection 

of, in, 564. 
purification of, 309. 
standard solution of, 628, 

634. 

volumetric estimation of, 

638. 

anhydride, 310. 

Sulphuris iodidum, 274. 

Sulphurous acid, 30, 305. 

volumetric estimation of, 
645. 
anhydride, 305. 
Sulphvdrate of ammonium, solu- 
tion of 96. 
Sulphydric acid, 301. 
Sumatra camphor, 421. 
Sunibul, 427. 
radix, 427. 
root, 427. 
Supporters of combustion, 23. 
Suppositoria acidi tannici, 358. 
cum sapone, 358 
morphinte, 517. 
plumbi composite/,, 211. 
Suppositories, 589. 
Surface unit, 603. 
Surgery, 15. 
Swamp sassafras, 509. 



788 



INDEX. 



Sweet birch, oil of, 407. 
flag, oil of, 420. 
spirit of nitre, 351, 403, 438. 
adulterated, 438. 
Sweetbread, 551. 
Sylvestrine, 412. 
Sylvic acid, 423. 
Symbol, function of a, 58. 
Symbols of elements, 32, etseq., 725. 
illustration of chemical action 
by, 46. 
Sympathetic inks, 236. 
Symmetrical compounds, 433. 
Synaptase, 500. 
Synthesis, 62. 
Syphon. See Siphon. 
Syrup, golden, 471. 
Syrups, 589. 

specific gravities of, 615. 
Syrupus, 469, 702. 

acidi hydriodici, 274. 

impurities in, 721. 
aurantii, 416. 

floris, 416. 
calcii lacto-phosphatis, 173. 
calcis, 108. 

impurities in, 721. 
ferri iodidum, 148. 
phosphatis, 146. 
subchloridi, 149. 

Tabacum, 539. 

Tabellse nitroglycerina, 458. 
Tables, various. See Appendix. 
Talc, 138. 
Tamarindus, 323. 

impurities in, 721. 
Tampico jalap, 505. 
Tanacetic acid, 507. 
Tanacetum., 507. 

Tannic acid, or Tannin, 357, 495. 
Tanning, 358. 
Tantalum, 726. 
Tapioca, 473. 

starch (fig.), 475. 
Tar, 413, 426. 
Taraxaci radix, 510. 
Taraxacin, 510. 
Tartar, cream of, 62, 79, 319. 
emetic, 189, 319. 

estimation of antimony in, 
671. 
meaning of, 319. 
soluble, 74. 

cream of, 334. 
Tartarated antimony, 181. 
Tartaric acid, 318, 496. 

saturating power of, 321. 
solution of, 320. 



Tartaric acid, volumetric estimation 
of, 639. 

series of acids, 496. 
Tartarus boraxatus, 334. 
Tartrate of ammonium, 99, 181. 

antimony and potassium, 181, 
319. 

calcium, 322. 

morphine, 517. 

potassium acid, 62, 74, 79, 318. 
neutral, 74, 320. 

and sodium, 87, 320. 

silver, 322. 

sodium, 321. 
Tartrates, 318. 

analytical reactions of, 322. 

volumetric estimation of, 632. 
Tartronic acid, 497. 
Taurine, 512, 552. 
Taurocholates, 552. 
Taxine, 542. 
Tea, 542. 
Teal oil, 464. 
Telini fly, 422. 
Tellurium, 726. 

Temperature, correction of volume 
of gas for, 619. 

quantitative determination of, 
594. 
Terebenthene, 412. 
Terebene, 413. 
Terebenurn, 413. 

impurities in, 721. 
Terebinthinse canadensis, 412, 427. 
Terephthalic acid, 497. 
Terpene series of hydrocarbons, 412. 
Terpenes, 412. 
Terpin hydrate, 413. 
Terpini hydras, 413. 

impurities in, 721. 
Terpinene, 412. 
Terpinol, 413. 
Terpin olene, 412. 
Terra di Sienna, 555. 
Tertiary alcohols, 436. 

amylic alcohol, 450. 
Terra japonica, 359. 
Test-papers, 96. 
Test-tubes, 16. 
Tetanine, 513. 
Tetano-cannabin, 423. 
Tetrabasic acid, 498. 
Tetrachloride of carbon, 401. 
Tetrachloromethane, 401. 
Tetrads, 124. 

Tetrahydric alcohols, 465. 
Tetra-iodo-pyrrol, 513. 
Tetramines, 512. 
Tetrane, 397. 



INDEX. 



789 



Tetrathionic acid, 346. 
Tetrylic acid, 488, 497. 
sulphocyanate, 415. 
Thalleioquin, 523. 
Thalline, 526. 
Thallium, 726. 
Thebaine, 518. 
Theia, 542. 
Theine, 542. 

relation to theobromine, 543. 
Thenard's blue, 555. 
Theobroma cacao, 462, 543. 

oil, 462. 
Theobromine, relation of, to theine, 
543. 

or Theobromia, 543. 
Theophylline, 543. 
Therapeutics, definition and deriva- 
tion of, 15. 
Theriaca, 471. 
Thermolysis, 622. 
Thermometers, 595. 

Celsius's, 595. 

Centigrade, 595. 

Fahrenheit's, 595. 

Reaumur's, 595. 
Thermometric scales, conversion of 

degrees of, 596. 
Thio-acids, 302. 
Thio-alcohols, 445. 
Thio-ethers, 445, 447. 
Thionic acids, 346. 
Thiosulphates, 345. 
Thorinum, 726. 
Thorium, 726. 
Thorn-apple, 538. 
Thorough wort, 509. 
Thus americanum, 427. 

masculum, 428. 
Thyme, 420. 
Thymene, 420. 
Thymol, 420. 

impurities in, 721. 
Thymus vulgaris, 417, 420. 
Tiglic acid, 464. 
Tiles, 355. 
Tin, 241. 

amalgam, 242. 

analytical reactions of, 243. 

antidotes to, 244. 

block, 241. 

chloride, 242. 

derivation of word, 34. 

dropped, or grain, 241. 

granulated, 241. 

oxide, 243. 

perchloride, 242. 

prepare liquor, 243. 

tacks, 242. 
34* 



Tin-foil, 241. 
Tin-plate, 242. 
Tin-stone, 241. 
Tin-white cobalt, 235. 
Tincal, 333. 

Tinctura ferri acetatis, 154. 
chloridi, 150. 
impurities in, 721. 

iodi, 274. 

nucis vomicae, 700. 

quininse, 523. 

ammoniata, 522. 
Tincturse, 150. 

Tincture of phenolphthalein, 639. 
Tinctures, 150, 589. 
Tinospora cordifolia, 509. 
Titanium, 726. 
Tobacco, 539. 
Toddaliae radix, 510. 
Tolene, 495. 

Tolu, balsam, 422, 429, 495. 
Toluene, 429, 431. 

dihydric alcohols, 456. 

sulphonic acid, 445. 
amide, 445. 
chloride, 445. 
Toluol, 431. 
Tolyl alcohol, 455. 

derivatives, 432. 
Tonic substances, 509. 
Tonka bean, 494. 
Toughened caustic, 218. 

nitrate of silver, 218. 
Tourmalines, 354. 
Toxicodendric acid, 361/ 
Toxicology, 561. 
Tragacanth, 116, 479. 
Tragacantha, 116. 
Tragacanthin, 479. 
Treacle, 471. 
Tree, lead, 215. 

silver, 220. 
Triads, 122. 
Triamines, 512. 
Triangle, wire, 100. 
Tribasic acids, 498. 
Tribasylous radicals, 124. 
Tribromophenol, 454. 
Tricarballylic acid, 498. 
Trichloracetal, 486. 
Trichloraldehyde, 485. 
Trichlorbutylidene glycol, 488. 
Trichlorethyliderje ethvl ether, 488. 

glycol, 486. 
Trichlorom ethane, 399. 
Trichloromethylbenzene, 336, 432. 
Triethylamine, 511. 
Triethylia, 511. 
Trigoneline, 543. 



790 



INDEX. 



Trihydric alcohols, 457. 
Trihydroxybenzene, 465. 
Trihydroxybenzoic acid, 493, 494. 
Trihydroxyl derivatives of the 

hydrocarbons, 457. 
Tri-iodomethane, 401. 
Trimethyl methane, 397. 

phenoene, 429. 
Trimethylamine, 512. 
Trinitrine, 458. 
Trinitrocellulin, 480. 
Trinitro-phenol, 454. 
Triphane, 227. 
Triple phosphate, 581. 
Tripoli, 354. 
Trithionic acid, 346. 
Triticum repens, 510. 

sativum, 473. 

starch, fig. of, 475. 
Trituratio elaterina, 503. 
Tritylia, 512. 
Trivalence, 56. 

Trivalent radicals, 56, 67, 123. 
Trochisci acidi tannici, 358. 

bismuthi, 252. 

ferri redacti, 158. 

morpMnse, 517. 

et ipecacuanhx, 517. 

potassii chloratis, 295. 

sodii bicarbonatis, 87. 

sulphur is, 303. 
Tropate of tropine, 532. 
Tropic acid, 532. 
Tropidine, 532. 
Tropine, 532. 
Tube-funnels, 22. 
Tubes for collecting gases, 68. 

glass. See Glass Tubes. 
Tungsten, 726. 
Tunicin, 480. 
Turgite, 153. 
Turkey corn, 536. 
Turmeric, 420, 554. 

oil, 420. 

paper, 96. 
Turmerol, 420. 
TurnbulPs blue, 161, 342. 
Turnsole, 555. 
Turpentine, 412, 427. 

American, 412. 

Bordeaux, 412. 

Canadian, 412. 

Chian, 412. 

French, 412. 

Russian, 412. 

impure, 412. 

rectified oil of, 412. 

spirit of, 412. 

Strasburg, 412. 



Turpentine, Venice, 412. 
Turpeth mineral, 201. 
Turps, 412. 

Tylophora asthmatica, 537. 
Type-metal, 180, 210, 251. 
Types, chemical, 379. 
Typical formulae, 379. 
Tyrosine, 513. 
Tyrotoxicon, 513, 571. 

Ulexine, 536. 

Ultimate analysis, 688. 
Ultramarine blue, 555. 

green, 556. 
Ultraquinine, 526. 
Umbelliferone, 428. 
Umber, 556. 
Uncaria gambler, 359. 
Unguentum aconitinse, 530. 
antimonii tartarati, 182. 
cerussse, 211. 

glycerini plumbi subacetatis, 212. 
hydrargyria 195. 
ammoniati, 207. 
iodidi rubri, 199. 
nitratis, 200. 

dilutum, 200. 
oxidi rubri, 204. 
sabchloridi, 203. 
iodi, 274. 
paraffini, 398. 
plumbi acetatis, 211. 
carbonatis, 211. 
iodidi, 213. 
potassx sulphuratse, 69. 
staphisagrise, 537. 
veratrinx, 544. 
zinci oxidi, 135. 
Unitary hypothesis, 286. 
Units of length, surface, capacity, 

and weight, 603. 
Univalence, 56. 
Univalent radical, 56, 123. 
Unsaturated hydrocarbons, 393. 
Unsymmetrical compounds, 433. 
Uranium, 726. 
Urari, 528. 

Urate of lithium, 228. 
Urates, 361. 
Urceola elastica, 420. 
Urea, 339, 489, 512, 575. 
artificial, 339, 578. 
nitrate of, 576. 

test for excess of, in urine, 
576. 
Urethane, 489. 

Uric acid, 361, 575, 579, 581, 587. 
Urinary calculi, 572. 

examination of, 587. 



INDEX. 



791 



Urinary deposits or sediments, 
plates of, 582. 
sediments, 579. 

microscopical examination 
of, 581. 
Urine, 361, 572. 
diabetic, 575. 
estimation of sugar in, 702. 

of urea in, 576. 
morbid examination of, 572. 
Urinometer, 575. 
Urobilin, 573. 
Uroerythrin, 582. 
Urostealith, 587. 
Uvse, 318, 469. 
Uva ursi, 359. 

Valency, 56. 

variation in, 139. 

conception of, 391. 
Valerine, 420. 
Valerian oil, 420. 
Valerianae, 420 
Valerianate of amyl, 333, 401. 

sodium, 362. 

zinc, 136, 363. 
Valerianates, 362. 
Valerianic or valeric acid, 362, 420, 

488. 
Valerol, 420, 427. 
Valerone, 498. 
Valylene, 412. 
Vanadates, 332. 
Vanadinite, 332. 
Vanadium, 332, 726. 

relationsbip to nitrogen, phos- 
phorus, and arsenum, 332. 
Vanilla, 364. 
Vanilla planifolia, 364. 
Vanillic acid, 364. 
Vanillin, 364. 
Vapor acidi hydrocyanici, 282. 

chlori, 29. 

coninse, 536. 

iodi, 273. 

olei pini sylvestris, 413. 
Vapor-density, 619. 
Variolaria, 556. 
Vegetable albumen, 548. 

alkaloids, 512. 

and animal life, relation of, 20. 

casein, 548. 

crocus, 554. 

fibrin, 548. 

gelatin, 479. 

screen, 556. 

jelly, 479. 

oil, 458. 

rouge, 555. 



Vegeto-animal alkaloids, 512. 

Venetian red, 153. 

Venice turpentine, 412. 

Veratralbine, 539. 

Veratri viridis rhizoma, 539. 

Veratridine, 544. 

Veratrina, 721. 

impurities in, 853. 
Veratrine, or Veratria, 539, 543. 

oleate of, 460. 
Veratroidine, 539. 
Veratrum album, 539. 

officinale, 543. 

viride, 539. 
Verbena oil, 420. 
Verdigris, 192. 
Vermilion, 208, 554. 
Veronica virginica, 510. 
Viburnin, 510. 
Viburnum, 510. 
Vinegar, 297. 

estimation of mineral acids in, 
682. 

of cantharides, 298. 

of squill, 298. 
Vinum album, 441. 

impurities in, 721. 

antimonii, 182. 

aurantii, 441. , 

ferri, 157. 

citratis, 157. 

ipecacuanhse, 537. 

quininse, 522. 

rubrum, 441. 

impurities in, 721. 

xericum, 441. 
Violet, salicylic acid in, 492. 
Virginia snakeroot, 510. 
Vitelline, 545. 
Vitellus, 545. 
Vitriol, blue, 144, 191. 

green, 144, 309. 

oil of, 309, 310. 

white, 144. 
Volatile oils. See Oils. 
Volatility of salts of ammonium, 99. 
Volatilization, 99. 
Volcanic ammonia, 91. 
Volume, combination by, 52. 

of gas, corrections of, 619, 620. 

molecular, 55. 
Volumetric quantitative analysis, 

625. 
Volumetric estimation of — 

acetic acid, 637. 

acid, phosphoric, 639. 

hypophosphorous, 639. 

acids, 636. 

acidum arsenosi liq., 646. 



792 



INDEX. 



Volumetric estimation of acidum 
hydriodici syrupus, 644. 
ammonia, solutions of, 629. 
ammonium bromide, 641. 

carbonate, 630. 
antimony, 646. 
arsenic, 647. 
barium dioxide, 653. 
calcium bromide, 642. 
chlorine, solution of, 656. 
citric acid, 637. 
ferrous arsenate, 650. 

carbonate, 653. 

phosphate, 651. 

sulphate, 653. 
hydrochloric acid, 637. 
hydrocyanic acid, 640. 
hydrogen dioxide, 653. 
hyposulphurous acid, 654. 
iodine, 656. 

compound tincture, 657. 

tincture, 657. 
iron, arsenate, 650. 

iodide, 644. 

magnetic oxide, 651. 

phosphate, 651. 

reduced, 653. 

saccharated carbonate, 650. 

sulphate, 653. 
lactic acid, 637. 
lead acetate, 631. 
lime, chlorinated, solution of, 

657. 
lime-water, 635. 
lithium bromide, 642. 

benzoate, 634. 

carbonate, 634. 

citrate, 634. 

salicylate, 634. 
nitric acid, 638. 
potash, 632. 
potassse liq., 632. 
potassium, 631. 

bicarbonate, 631. 

bromide, 642. 

carbonate, 631. 

citrate, 632. 

cyanide, 641. 

iodide, 643. 

permanganate, 635. 

tartrate, 632. 
soda, 632. 

chlorinated solution of, 657. 
sodse liq., 632, 
sodium, 631. 

arsenate, 646. 

bicarbonate, 631. 

bisulphite, 648. 

bromide, 642. 



Volumetric estimation of sodium 
carbonate, 631. 
citrate, 632. 
hyposulphite, 647. 
sulphite, 647. 
tartrate, 632. 
spiritus ammonise aromaticus, 630. 
strontinum bromide, 643. 

lactate, 633. 
sulphuric acid, 639. 
sulphurous acid, 646. 
tartar emetic, 647. 
tartaric acid, 639. 
zinc bromide, 643. 
chloride, 643. 
iodide, 643. 
Volumetric solutions, 628, 534, 636, 

639, 645, 648, 652, 655. 
Vulcanite, 420. 
Vulcanized india-rubber, 420. 

Wahoo bark, 510. 

Wakhuma, 530. 

Warmth of animals, how kept up, 

20. 
Washing bottles, 109. 

flasks, 109. 

precipitates, 110. 
Wasp-sting, 339. 
Water, 127. 

aerated, 88. 

ammonia in potable, 630. 

baryta-, 103. 

boiling-point of, 596. 

chalybeate, 142. 

chlorine-, 28, 267. 

chloroform-, 401. 

composition of, 22. 

cubic inches of, in a gallon, 621. 

distilled, 128. 

estimation of, 687. 

evaporation of, 71. 

formation of, expressed by sym- 
bols, 46. 

hardness of, 315. 

hemlock-, 417. 

lead in, 214. 

lime-, 108. 

nitrites in, 350. 

of crystallization, 85, 139. 

oxygenated, 103. 

potash-, 72. 

preparation of, 22. 

purification of, 127. 

quantitative estimation of, 687, 

soda-, 86. 

softness of, 315. 

weight of a cubic inch of, 608, 
621. 



INDEX. 



793 



Water, weight of minim, drachm, 
ounce, pint, and gallon, 608. 
Water-aspirator, 309. 
Water-bath, 109, 112. 
Water-oven, 660. 
Water- type, 379. 
Wax, 450. 

Chinese, 450. 

paraffin, 399. 
Wedgewood ware, 355. 
Weighing-tubes, 660. 
Weight, 600. 

estimation of, 600. 

molecular, 55. 

definition of, 59. 

of air, 620. 

of hydrogen, 620. 

of water, 621. 

specific, 600, 613. 
Weights, atomic, 52. 

balance, 600. 

and measures, 600. 

and measures of the metric 
decimal system, et seq., 601. 
of the British Pharmaco- 
poeia of 1885, 608. 

relative, 52. 

of litres at different tempera- 
tures, 620. 
Weld, 554. 
Welding, 142, 249. 
Wheaten flour, 473. 
Wheat starch (fig.), 475. 
Whey, 411, 546. 
Whiskey, 441. 
White arsenic, 168. 

Castile soap, 461. 

indigo, 201. 

lead, 210, 557. 

marble, 106. 

pepper, 541. 

pigments, 557. 

precipitate, 206. 
fusible, 206. 
infusible, 207. 

resin, 423. 

vitriol, 144. 

wax, 450. 
Whiting, 121. 

Whortleberry, sugar in, 467. 
Wild indigo, 530. 
Wild black-cherry bark, 500. 
Willow-bark, 456. 506. « 
Wine, 441. 

antimonial, 182. 

apple, 441. 

heavy oil of, 409. 

ipecacuanha, 537. 

iron, 157. 



Wine, oil of, 409. 

orange, 441. 

pear, 441. 

quinine, 522. 

sherry, 441. 

steel, 157. 
Winter-green, oil of, 407. 
Wire triangle, 100. 
Wire-gauze tray, 29. 
Witch-hazel, 509. 
Witherite, 103. 
Wood, specific gravity of, 618. 
Wood-charcoal, 113. 
Wood-creasote, 453. 
Wood-naphtha, 437. 
Wood-oil, 429. 
Wood-spirit, 437. 
Wood-tar, 413, 426. 
Woody night-shade, 541. 
Wool fat, 461. 
Woorara, 628. 
Wormwood, 417, 479. 
Wourali, 628. 
Wrought iron, 142. 

Xanthine, 543, 589. 
Xanthocreatinine, 513. 
Xanthorrhiza apiifolia, 533. 
Xanthoxylon fraxineum, 533. 
Xanthoxylum, 533. 
Xylene, 429. 
Xylenes, 455. 
Xyloidin, 473. 
Xylonite, 480. 

Yard, 608. 

Yeast, 439. 

Yelk of egg, 545. 

Yellow chromate of potassium, 105. 

coloring-matters, 553. 

dock, 338. 

ochre, 553. 

oxide of mercury, 204. 

parilla, 533. 

prussiate of potash, 280. 

sienna, 553. 

soap, 462. 

wax, 450. 

wood, 553. 
Yolk of egg, 545. 
Ytterbium, 726. 
Yttrium, 726. 

Zaffre, 235. 
Zanaloin, 435. 
Zanzibar aloes, 435. 
Zea mays, 472. 

starch of (fig.), 475. 
Zinc, 131. 



794 



INDEX. 



Zinc acetate, 134. 

analytical reactions of, 136. 
antidotes to, 137. 
bromide, 134. 

volumetric estimation of, 
643. 
carbonate, 131, 134. 
chloride, 132. 

volumetric estimation of, 
643. 
derivation of word, 33. 
detection of, in presence of 

aluminium and iron, 163. 
ethide, 397. 
ferrocyanide of, 137. 
granulated, 21. 
hydrate, 136. 
in organic mixtures, detection 

of, 564. 
iodide, 134. 

volumetric estimation of, 
643. 
molecular weight of, 195. 
oleate of, 136, 460. 
oxide, 135. 
phosphide, 328. 

quantitative estimation of, 667. 
sulphate, 131. 
sulphide, 136. 

native, 131. 
sulphite, 136. 
sulphocarbolate, 454. 



Zinc, valerianate, 136, 363. 

white, 134. 
Zinci acetas, 135. 

impurities in, 721. 
bromidum, 134. 

impurities in, 721. 
carbonas, 134. 

prsecipitatus, 134. 

impurities in, 721. 
chloridi liquor, 133. 
chloridum, 131. 

impurities in, 721. 
iodidum, 134. 

impurities in, 721. 
oleatum, 136. 
oxidum, 135. 

impurities in, 721. 
phosphidum, 387. 

impurities in, 721. 
sulphas, 131." 

impurities in, 721. 
sidphocarbolas, 454. 
unguentum, 135. 
valerianas, 136, 363. 

impurities in, 721. 
Zincum, 21, 131. 

impurities in, 721. 
Zingiber, 420. 
Zirconium, 726. 
Zymotic alkaloids, 513. 
Zymosis, 441. 



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